Vet School/Universidad de la República/ UDELAR – Uruguay

Medical English course for Vets II

Summary – Nr. 1- November 2010

2 – Summary 3 – Editor’s note 4 - Mastitis Part 1 - The importance of mastitis 8 - Mastitis Part 2 - The Bacteria 10 - Mastitis Part 3 – Getting The Most From Cell Counts

13 - Mastitis Part 4 – Detecting and Treating Mastitis 16 - Mastitis Part 5 – Bactoscan: Problems and Solutions 20 - Mastitis Part 6 – Good Parlour Routine 24 - Mastitis Part 7 - Teat Disinfection 27 - Mastitis Part 8 – Dry Cow Therapy

29 - Mastitis Part 9 - The Milking Machine 31 - Mastitis Part 10 –Environmental Mastitis

Bibliography: http://www.nadis.org.uk/RegionsFrames/EM_CattleTop.html

Editor’s Note

by Prof. Carmen Silvia Gallo Muniz

Hello, there!! This is the first magazine in English, I have created for the Medical English Course

II, delivered through my virtual classroom placed in the Moodle platform of the Vet

School/Universidad de la República de Uruguay (UDELAR). This magazine is also

the result of a course I have taken to implement NICT in my teaching practice.

Today’s topic is Mastitis. The information for this magazine, were taken from:

http://www.nadis.org.uk/RegionsFrames/EM_CattleTop.html, “NADIS, National

Animal Disease Information Service, promoting disease prevention and control, in

order to benefit farm animal health and welfare”, and it was written by Richard

Laven PhD BVetMed MRCVS, I only compiled them for the benefit of my students.

Some useful information about NADIS’ duty …” East Midlands Cattle Health

KnowledgeTransfer - Improve your profits with better animal health. As part of

the LandSkills Programme to improve animal health and farm profitability in the

East Midlands a series of training seminars and workshops on key livestock

diseases are being held by veterinary practices across the region. (Please see

training events page for dates). The LandSkills Programme is jointly funded by the

European Agricultural Fund for Rural Development and DEFRA. LandSkills is

managed by Lantra on behalf of EMDA”... They are located in England.

I kindly thank NADIS and the task they performed and also Dr. Richard Laven

PhD BVetMed MRCVS, for their great job and generosity, be sure you are both,

contributing to the comprehensive training of veterinarians in my country and also

helping them to acquire and improve their knowledge of the English Language,

which is at the same time an addition that enhances their practice.

I do really hope my students enjoy it.

See you soon with another important topic!!

Kind regards,

The Editor

Contact the editor at englishforvet@gmail.com

Mastitis Part 1 - The Importance of Mastitis Of all diseases of cattle, mastitis, inflammation of the udder, is the disease which costs the most. Cows with mastitis produce less milk, get pregnant less quickly, lose more body condition and are more likely to be culled early. As well as affecting production and profitability, mastitis has a major welfare impact; next to lameness it is probably the disease with most effect on cow well-being. Yet of the three major dairy herd problems, i.e. mastitis, fertility and lameness, mastitis is the disease that a well-planned control programme can have the most impact on. This series of bulletins aims to give you the tools to plan with your vet how you can minimise the impact of mastitis on your farm. How much does mastitis cost? The cost of mastitis is not just the cost of the

antibiotic tubes you buy from your vet. That is just the most obvious cost. Treatment costs are generally <15% of the cost of mastitis. Most of the

cost of mastitis results from the reduction in milk yield because of udder damage. This effect is long-

lasting. Cows with mastitis tend to produce less milk not just in the affected lactation but also in

subsequent lactations. Published costs of mastitis vary widely. One figure

often quoted is a cost of £70 – £250 per cow per

year, i.e. on a 100 cow herd, the cost of mastitis

could be between £7,000 and £25,000. There are

several reasons why this figure ranges so widely: 1) The number of clinical cases. The average

number of cases ranges across studies from

around 30 cases per 100 cows per year to over 70. Individual farm levels are even

more variable. 2) The degree of subclinical mastitis. Herds

with a high level of subclinical mastitis (i.e. a high bulk milk cell count) will be losing more money than a herd with the same number of cases of clinical mastitis but a lower bulk milk cell count. Although farms with high numbers of clinical cases tend to have higher cell counts the link is not absolute. When looking at the cost of mastitis on-farm both types of mastitis need to be taken into account.

3) The cost per case of mastitis. This varies from farm-to farm because of the differences between farm systems. A recent survey using farm data found that the actual cost of a case of clinical mastitis ranged from £149-£250. So differences in numbers of clinical and subclinical cases, combined with differences in the actual losses for each cases lead to large differences between herds in the cost of mastitis.

We have to get away from generic averages.

When looking at mastitis control, we need to

focus on the individual farm and identify the

Richard Laven PhD BVetMed MRCVS Fig 1: Hard swollen udder – classic sign

of clinical mastitis Fig 2: Teat disinfection is a crucial part

of mastitis control

costs of mastitis on that farm. Working together

the veterinarian and the farmer will then be able

to identify the prevention programme which will

have the most benefit on that farm.

Recording mastitis. All herds have weekly bulk milk cell counts, many

have at least monthly herd testing. These records

are extremely valuable and have undoubtedly

played a major part in the reduction in average herd

cell count since the 1970s, but to properly assess

the cost of mastitis and manage it effectively, we

need more than just cell count records. The main area we need better records is in clinical cases, i.e. cases treated on-farm with antibiotics

because of changes in the milk and/or udder. Antibiotic use, provided it follows recommended treatment regimes, can give a guide as to how many

cows have been treated. However we need good clinical records to determine how many cows are

treated more than once, how effective treatment is – both in terms of clinical signs and cell count, and the

stage of lactation at which cows are being treated.

Monitoring mastitis Once the costs and the areas of concern have been

identified, then a control programme can be

developed for the farm. This plan should identify

what the aim is on the farm, in terms of mastitis

management, what the main constraints are to

achieving that goal, the key changes that need to be

made, and their likely benefits. However that is not the end of the story. It is essential to monitor the response to the plan and to then modify the plan based on the initial response. Without monitoring, the plan is simply a piece of paper and an interesting discussion. This is because, just as it is not possible to assign a single figure to the cost of mastitis, it is not possible to completely predict the response to an individual control measure. Different farms will have different responses to the same measure. So, just as the evaluation has to be individualised, the response has to be individualised too.

Fig 3: Culling of cows with chronic mastitis

costs money in the short term but over the long

term is essential if mastitis is to be effectively

controlled Fig 4: Dry cow management is not just

antibiotics; a good clean environment is also

important

The DairyCo mastitis plan This evaluate, implement, monitor and revise formula has been developed into the DairyCo mastitis plan. That plan builds on the original 5-point plan to provide individualised mastitis control that is targeted to the problems on the individual farm and which provides bespoke control measures which are designed to work with the farm’s long term aims and goals. The DairyCo plan has been shown to significantly improve the mastitis situation on farms which implement the plan. Not all farms will show this improvement in the first year, but with monitoring and active revision and participation in the plan by both the veterinarian and the farmer, over the longer term individualised programmes are the key to mastitis control.

Fig 5: Regular maintenance of the milking

machine greatly reduces the risk of it

causing mastitis.

*Hygienic teat management *Prompt identification and treatment of clinical

cases *Dry cow management and therapy

*Culling of chronically infected cows *Regular milking machine maintenance and

testing Table 1: The Five-point plan – This is the basis of

all mastitis control plans but every farm needs

its own individual plan with individualised

solutions targeted at the problems on that farm.

SUMMARY

1. Mastitis is both expensive and a welfare issue 2. The cost of mastitis varies widely between

farms

3. The type of mastitis varies widely between

farms

4. Farm-specific control programmes are

needed to tackle mastitis effectively

5. Developing such programmes

requires effective recording of mastitis 6. Constant monitoring and assessment of

mastitis control programmes is essential

Mastitis Part 2 – The Bacteria Mastitis in dairy cattle is almost always caused by

bacterial infection. Understanding which bacteria are

causing mastitis on your farm can provide you with

significant information as to what the likely key risk

factors are and to what control measures you need

consider. Mastitis-causing bacteria are usually divided in two

groups: environmental and contagious. Environmental

bacteria usually come from the environment so spread

outside of the milking parlour, while contagious bacteria

generally spread during milking. This division is not

complete, some environmental bacteria can spread during milking and some contagious bacteria spread

outside of milking, but it’s a useful starting point. A good example of the difference between the two groups is the role of the dry cow period. Most infection during the dry period comes from environmental bacteria, so if you have a peak of mastitis in the first few days after calving then it is likely to be a problem with the environment, particularly the environment in the late dry period. However if mastitis peaks 10 – 14 days after calving them a milking machine problem is more likely. It is important to stress that these are useful rules rather than laws, and individual farm investigation and bacteriology is required to confirm these suspicions. Environmental bacteria The two most common environmental bacteria which cause mastitis are E. coli and Streptococcus (Strep.) uberis. Their relative importance has increased since the

introduction of the five-point plan which focussed on controlling contagious mastitis. Both bacteria can cause a wide variety of signs, ranging from inapparent subclinical mastitis to severe, toxic mastitis. Traditionally E. coli

mastitis has been more commonly associated with toxic

mastitis and a severely ill cow, but it is now more commonly seen in association with a much milder form of the disease. Strep uberis is most commonly associated

with relatively moderate mastitis with no systemic signs Strep dysgalactiae is the third most common environmental

bacterium. It currently causes mastitis much less commonly

than either Strep. uberis or E. coli because it can generally

be effectively controlled by following the five-point plan. This

is because spread in the milking parlour is more common for

Strep dysgalactiae than the other environmental bacteria

and because its most common site outside of the udder is

teat skin so post-milking teat dipping will reduce mastitis risk Contagious bacteria The two most important contagious bacteria are Staphylococcus (Staph.) aureus and Strep. agalactiae. The latter bacteria used to be the most important cause of clinical mastitis and high cell count but because it is only found in the udder it is effectively controlled by the five-point plan. However Staph aureus has been less well controlled by the plan and is the third most commonly isolated bacterium from milk samples sent to the VLA / SAC. Staph aureus can cause a wide variety of signs

Richard Laven PhD BVetMed MRCVS

Fig 1 ( a - e below): Good sampling

technique is essential if contaminated

samples are to be avoided

a: Label the tube

b: Clean the teat end thoroughly

c: Avoid contaminating the lid

d: 5mL of milk is all that is needed

e: Get the milk cool as soon

as possible after sampling

EBLEX – Improving Beef and Sheep Health

including a severe, toxic mastitis, but it is as a cause of

high cell count problems that it is most commonly

encountered. This is because Staph aureus often sets up

a chronic, grumbling, walled-off infection deep in the

udder. These can be very difficult to treat. Sampling for bacteriology Identifying which bacteria are causing the problem is an

important part of any mastitis management plan. There

are two key rules for sampling: 4) Sample the cows that are representative of your

problem. If the main problem is a high cell count without obvious signs then samples from clinical cases will be of little value and vice-versa. It is fairly easy to get representative samples if you have a cell count problem as you can sample 10 – 12 cows with high cell count and get useful results within 24-48 hours. However if it is a clinical problem then many of the samples you want will be in the past as the cows have been treated, and you may have to wait a considerable period of time before you can collect 10 or so samples. It’s thus a good idea to collect a sample from every cow that has mastitis before you treat her and to freeze it. So if you develop a problem, you have representative samples available with no waiting period.

5) Take clean samples so that the only bacteria in

the milk are those causing the mastitis. Aseptic

technique is essential as many of the bacteria

which cause contamination can also cause

disease, which means that contamination can

lead to misdiagnosis and frustration as well as

increased costs. A good technique is

summarised below:

Fig 2: A pure culture of the organism

causing the mastitis is the goal

Fig 3: A chronically infected shrunken

quarter is often secondary to Staph aureus

infection

Sampling milk for bacteria (see photo sequence on first page)

1) Label the tube with cow and quarter

2) Remove loose dirt, bedding etc. from the udder with a paper towel. Only wash the

udder and teats if they are grossly dirty. Always dry thoroughly

3) Discard a few streams of milk

4) Clean the teat end with an alcohol wipe for at least 10-15 seconds. If necessary use

additional wipes until no more dirt is visible on the wipe or the teat end

5) Take the cap off the sterile sample pot, keeping the open end facing downward 6) Keep the pot at a 45

0 angle, don’t allow it to touch the teat end

7) Discard a few streams of milk

8) Collect up to 5mL of milk, 2-3 mL is usually sufficient

Mastitis Part 3 – Getting The Most From Cell Counts High cell counts cost money. The cost of a high cell count doesn’t just come from the penalties imposed or bonuses foregone when targets are not met; high cell count cows produce less milk than low cell count cows. A high cell count herd will also have more clinical mastitis. So reducing cell count can provide substantial savings – on average, reducing the bulk cell count from 250,000 to 150,000 will result in savings of around £40 per cow per year, most of which comes from a reduction in production of around 0.5L more of milk per day. So cell counts are a valuable tool which can be used to identify a problem, assess the cost of the problem, give a guide as to the solution, and to monitor the response to control programmes. What is a somatic cell count (SCC)? Just like any other organ, when the udder is infected

somatic cells from the blood (white blood cells) move

to the udder and into the milk to defend the organ

against the invading bacteria. Without this response,

elimination of mastitis, even mild cases, would be

very slow and tissue damage greatly increased. The stimulus for this invasion is tissue damage. This

releases a range of chemicals including some which attract the white blood cells to the damaged tissue

and some which activate them. The white cells then

attack and attempt to destroy the invading bacteria.

Most commonly, the white blood cells envelop the

bacteria and internalise them. They then attempt to digest the bacteria using enzymes. Somatic cell counts simply measure the number of cells in the milk; the higher the somatic cell count the

greater the chance that the udder or quarter is infected. Uninfected cows and quarters often have a

milk SCC of <100 000/ml, and almost always have a SCC <200 000. The same applies to bulk milk SCC

– on average, the higher it is the higher the proportion of infected cows in the milking herd. With good mastitis control, the bulk milk SCC should be

below 200 000. Can cell counts be too low? For an individual cow the ideal cell count is 100 – 150,000. Below 50,000, there is some evidence that cows respond more slowly to infection, particularly with E. coli, so they have an increased risk of mastitis. So as reducing bulk milk below

100/150,000 may increase the proportion of very low cell count cows, it may also increase the risk of clinical mastitis. Nevertheless because of the other benefits of low bulk cell count the answer is not to increase cell count but to maximise immunity (such as by minimising negative energy balance) and to keep the cows in as good an environment as possible.

Richard Laven PhD BVetMed MRCVS

Fig 1: A California milk test kit. This adds

the test liquid to all four wells at the same

time – useful if large numbers of cattle are

tested at the same time

Fig 2: Clumping of the milk and test liquid

mixture indicates subclinical mastitis Figs 3a & 3b: Some cows with high cell counts

are obvious (above), some are not (below)

Detecting high cell counts Changes in bulk milk SCC reflect changes in the underlying cell count of the milking herd, so bulk milk SCC can be used as an early warning system to identify increases in the number of infected cows. Over the long term, bulk milk SCC can also be used to detect seasonal trends in cell count, which can be useful in identifying mastitis risk factors However, bulk milk SCC is a fairly crude and unresponsive measure. Often by the time that bulk milk SCC has risen there has been a significant increase in the proportion of infected cattle. Bulk milk SCC also underestimates the average SCC of the milking herd – partly because high cell count cows are often excluded from the bulk tank but also because the two measures are not the same. Furthermore, because it’s a bulk measure it provides very little data on the number of infected cows and the dynamics of mastitis in the herd. Individual cow SCC is a much more valuable measure. Regular measurement of individual cell count at herd testing can provide data on the proportion of infected cows, which cows are infected, how long they stay infected for, the rate at which new infections are occurring, and seasonal impacts on those data. Although regular herd testing is the best method of detecting high cell counts in individual cows, a cheaper alternative, which can also be used in an

emergency if a herd test is not available, is the California mastitis test. This is a cow side test which

uses the fact that when mixed with a detergent, the DNA in the white blood cells is released. If the cell

count is high enough a visible gel will form (Fig 2). The CMT test is performed using a four well paddle (Fig 1) as described below

1) Discard foremilk 2) Squirt milk into wells – one per quarter 3) Add equal amount of reagent and mix 4) Reaction is scored on a scale

of 0 (no change) to 3 (almost

solid) Special reagents are available but recent research

has shown that a mixture of 1 to 4 Fairy liquid to

water is just as effective, particularly if a few drops of

food colouring are added, and much cheaper.

Cheaper detergents tend to not be as effective. One advantage of the CMT over an individual cell

count is that all four quarters are tested whereas an

Figs 4: Cows with low cell counts (<50,000) may

be at an increased risk of toxic mastitis, but this is

best tackled by improving environment and

immunity rather than trying to increase cell counts individual cell count is a cumulative count of the

quarters. This means that 3 normal quarters can mask the effect of an abnormal one – e.g. a cell

count of 500 000 in one quarter and 100 in the other

three will result in a whole udder cell count of around

200 000. Individual quarter herd tests are cost

prohibitive in most situations, so using a CMT on at-

risk cows is a useful exercise. Using cell count data Individual cell counts tell you what the current infection status of the cow is likely to be. However a single figure on its own is of limited value. Firstly there is the masking problem discussed above. Secondly, the most obvious cows on a single herd test are those with the highest SCCs. These cows are likely to have long established infections that which will not respond well to treatment. These cows need to be managed to reduce the risk they pose to the rest of the herd, by techniques such as culling, early drying off or milking separately, but the time has long past for simple identification and treatment. The more important cows are those with persistent infection but lower cell counts (see Fig 5); early detection and treatment of these cows is likely to have the most benefit. The best use of SCC is as a dynamic test with multiple results per cow; this will allow early identification of persistent rises in cell counts in cows to < 400 000 (Fig 6). Working with your vet, you can use your routine herd

test to identify what the underlying cell count

problem is, what the main risk periods are and what

are likely to be the best solutions for your herd. Herd

testing provides individualised data to be used in an

individualised herd health plan; the underlying

principle of the DairyCo mastitis plan.

Fig 5: Distribution of the latest high SCC in chronically infected individual cows. In a problem herd

most infected cows will have a cell count <500 000. Focussing only on the worst cell counts will miss

these cows

Fig 6: Distribution of the initial high SCC in cows which become chronically infected

during lactation – this shows that most cows which become chronically infected start off

with a raised cell count < 350,000, and a quarter with a cell count < 250 000. You need

multiple cell count results to pick these cows up (Figures 4 and 5 from Hanks and Biggs UKVet)

Summary

High somatic cell counts, either bulk or individual, mean money is being lost.

When a cow has mastitis, white blood cells move to the udder to defend it. It is this

movement of white blood cells which causes the rise in cell count.

Effective mastitis control should keep bulk milk and individual cell counts < 200 000

Bulk milk cell counts are available from routine test and provide useful data, but

for effective control monthly herd testing of individual cows is required

The California milk test is a cheap, but time consuming alternative to herd

testing, that is best saved for individual cows or emergencies

The use of computer programmes has revolutionised the value of herd testing.

they can quickly identify trends in cell count and identify target areas for mastitis

control

Mastitis Part 4 – Detecting and Treating Mastitis Mastitis management should be focussed on

preventing disease, but if disease does occur then it

needs to be promptly identified and treated. Foremilking Stripping milk from a cow and examining it, prior to milking, is still the best method for detecting most early cases of clinical mastitis. This is because changes in the milk are often the first sign of mastitis. Milk changes (clots, flecks, changes in colour or consistency) can be seen when milk is stripped on to a dark surface. The changes in milk are related to the causal organism with clots and flakes tending to be more common in mastitis due to Staphs and Streps, while straw-coloured milk is typically associated with E. coli. There is

considerable overlap and other factors need to be taken into account when deciding what treatment to use. Examination of the foremilk is easy to do and

requires no specialized equipment, so is available to

every stockperson. Nevertheless, probably less than

10% include it in their milking routine, mainly

because of the time it takes. Examining the udder Visual examination and palpation of the udder prior

to putting on the clusters should be part of all milking

routines. Mastitis causes udder swelling, reddening,

hardness, heat and pain which can often be

detected even with a fairly cursory examination. The problem with relying on udder examination as

the first line of mastitis detection is that udder

changes are detectable fairly late in the process, so by the time disease is detected considerable losses

have occurred. Later identification also means

delayed treatment, which tends to be less effective

than early treatment and increases the risk of

disease spread In-line filters Many plants have mastitis detectors fitted in the long

milk tubes. These can be useful if checked after every cow is milked. However, in direct-to-line

parlours milk is in the tank before infection is identified, also in-line filters can restrict milk and air flow through the long milk tube reducing milking

machine efficiency. Checking the main milking plant filters for clots at the end of milking is common

practice but should not be used as a method of early mastitis detection! Conductivity Mastitis changes the concentration of ions in the

milk, which changes its electrical conductivity. Such

changes can occur 24 to 36 hours before visible

signs develop. This has lead to the development of

cow-side and in-line conductivity meters.

Unfortunately, detecting mastitis using conductivity

Richard Laven PhD BVetMed MRCVS

Fig 1: Stripping milk onto a dark surface before

milking the cow is a simple and effective method

of early mastitis detection.

Fig 2: Conductivity can be used to detect

early mastitis but it is not a simple alternative to examining foremilk. Picture from qmps.vet.cornell.edu/Services/lactocorder.htm

Fig 3: The main milking plant filter should not

be used as a method of mastitis detection

is not as simple as measuring cell count. Firstly, there is no single threshold; different cows have different conductivities so to detect mastitis you need to detect a change in conductivity which requires multiple tests. Secondly, whole cow conductivity is not sensitive enough – changes in an affected quarter can easily be swamped by the lack of change in the other three quarters. So individual quarter tests are needed. This means that in a 100 cow herd, 400 conductivity tests are needed every milking. So conductivity monitoring requires a dedicated computer programme to deal with all the data. Finally, even with a false positive rate of <0.5% per test this means that in a 100-cow herd, two cows will be wrongly flagged as having a new case of mastitis every milking – most rises in conductivity are not due to mastitis. It is best used as a screening test to identify cows for closer examination.

Grading mastitis Once it is identified, it is important to identify the severity of mastitis

as this is crucial in determining what treatment to give. Mild mastitis: Abnormality of the milk is the main sign with little

evidence of change in the udder and no systemic signs such as

dullness and loss of appetite. Moderate mastitis: Changes in the udder are detectable as well as

changes in the milk. These changes can occur slowly or rapidly.

There may be small systemic changes such as reduction in feed

intake. Over a long period of time both of these types of mastitis can persist,

leading to chronic inflammation and damage in the udder (chronic

mastitis) Severe mastitis: Marked changes in the udder and milk are

combined with major systemic effects in the cow such as fever, loss

of appetite, depression, shock, dehydration, and collapse. These

cows need urgent veterinary attention. Treating mastitis during lactation There are two aims of mastitis treatment:

1) Returning milk to normal with an acceptable cell count so that

it can be sold again 2) Getting rid of the bacteria

The first is easier than the second. Mild mastitis can often disappear in a few days with no treatment or with massage and hand stripping

of the quarter. However the bacteria may still be there. The same process may also occur after antibiotic treatment, particularly short courses with short milk withholds. Getting a visible cure without a

complete bacteriological cure may result in an increase in subsequent clinical infections and a permanently raised SCC. Antibiotics These are the basis of most treatment regimes. There are two

options: intramammary antibiotics, the classic mastitis tube and

systemic antibiotics given by the intramuscular or subcutaneous

route.

Fig 4: Treatment with intramammary

antibiotics remains the basis of most

mastitis treatment

.

Fig 5: There is little sense in treating

an older cow with chronic Staph

aureus and a persistently high cell

count

Fig 6: Cows that are sick because of

mastitis need immediate veterinary

attention

Intramammary antibiotics should be the first-line treatment for cows with mild uncomplicated mastitis

in a single quarter. Systemic antibiotics should be used when more than one quarter is affected, when

udder changes are marked or when the cow is obviously ill. Combination therapy, with both systemic and intramammary antibiotics, is a useful

way of increasing bacteriological cure rates particularly in herds where recurrent mastitis is a

problem. All farms should have an individualised standard operating procedure (SOP) for the treatment of mastitis with antibiotics. This should include details such as when to use intramammary antibiotics, when to use systemic therapy and when to use combined treatment, as well as guidance on when not to treat because the cow is unlikely to respond (a high SCC cow with a history of Staph. aureus

infection). It should also detail the products available to the staff that have been prescribed for mastitis treatment on that farm. All staff milking cows should be familiar with this SOP. Non-steroidals (NSAIDs) These are aspirin-like drugs which reduce the inflammation and pain associated with mastitis. They

are very useful in severe cases of mastitis, but there is less evidence of usefulness in mild to moderate

cases. However, they may be beneficial in these cases too – a recent study showed that cows treated

with systemic antibiotics and NSAIDs had lower cell counts and cull rates than cows treated with antibiotics alone - but more research is needed. Treatment ‘failure’ There are four reasons why treatment does not

result in return to normal: 1. Wrong antibiotic – mastitis-causing

organisms not killed by the chosen

treatment 2. Not enough antibiotics for long enough at

the site of infection – although bacteria are

killed, not all are and return after the end of

treatment.

3. Re-infection – treatment works but cow

gets re-infected 4. Wrong cow – persistent damage to the

udder can prevent the antibiotic from coming

into contact with the bacteria in sufficient

concentration Most intramammary antibiotics are designed to be effective against most common mastitis pathogens, but some have a narrow spectrum. Systemic antibiotics tend to have a narrower spectrum. So determining antibiotics to use for first-line should be based on a thorough understanding of the main pathogens on your farm. This is critical to the development of your mastitis SOP; input from your veterinarian is essential in determining the most appropriate antibiotics to use on your farm. True antibiotic failure is a rare cause of poor treatment response. Antibiotic treatment of mastitis is aimed at getting the cow back into milk as soon as possible – short courses with low amounts of antibiotics with short milk withholds. This reduces the chance of killing all

the bacteria. Longer treatment is more effective but more expensive, but it should be considered on farms where recurrent cases are a problem, and when apparent cure rates after standard courses are lower than expected. Again, changes in antibiotic treatment length need to form part of your mastitis treatment SOP, and veterinary advice is crucial. For some cows no matter how much antibiotic you use the chances of cure are very low. For example a

5-year old cow, treated at 150 days in milk, with a SCC of 2,000,000 cells/mL because of Staph aureus

infection has approximately 1% chance of cure. The

main reason for failure in these cases is that the antibiotics never reach the bacteria in sufficient

concentration. These cows need to be identified and removed from the herd. Treatment will not be

economic

Summary

1. Mastitis may result in changes in the milk, udder and cow or any combination.

2. Foremilking is the best method of early mastitis detection - clots, flecks, and changes in colour or consistency can be seen when milk is stripped on a dark surface.

3. Observation and palpation of the udder is essential but tends to detect only later or more severe mastitis cases. 4. Mastitis can be treated by intramammary or systemic antibiotics or a combination of both. 5. Intramammary drugs tend to be best for single quarter mild mastitis, while systemic treatment is better for more

severe cases or multiple quarter infection. 6.An SOP that is available for all staff should be developed for mastitis treatment with antibiotics. 7. Apparent treatment failure is usually due to insufficient antibiotics being given for too short a period of time.

However, not all cows will respond to treatment. Identify these cows before wasting money on antibiotics.

Mastitis Part 5 – Bactoscan: Problems and Solutions Milk needs to be produced as hygienically as possible. Bacterial contamination is the most important cause of hygiene-related problems as milk is a superb source of food for bacteria. When milk is

at a temperature of about 35oC bacterial numbers

can double within half an hour- so, within two hours, 1,000 bacteria in a mL of milk can become 10,000 bacteria and, within 5 hours, 1,000,000.

Temperature is key, below 5oC the bacteria which

affect milk quality do - not multiply. However, the bacteria are not killed they are just dormant waiting for an increase in temperature to start reproducing again. High levels of bacteria in milk affect both its manufacturing properties and its shelf life What is a Bactoscan? Historically, the bacteriological analysis of raw milk was made using simple culture, with the bacterial count being based on the number of visible colonies on the culture plate. This process was slow and expensive. In the early 1980s an automated process of bacterial counting, Bactoscan, was developed. This is now the standard system in the UK. Milk is

centrifuged to separate the bacteria and other heavier particles from the main body of the milk, the bacteria stained, and then counted. The process takes less than 7 minutes, a huge improvement over the turn-around time required for culture, and, unlike culture, it can be completely automated. Bactoscan results are not the same as culture

results. Bactoscan measures the actual number of

individual bacteria whereas culture measures the

number of colonies which grow in the laboratory.

Culture is therefore affected by the natural tendency

of bacteria to clump together in milk – reducing the

number of colonies which form. Where do the bacteria come from? Bacteria are everywhere, in dirt, on skin, on the

cows, in the water and in the air. The main challenge

in ensuring good hygiene in the dairy, is preventing

the normal level of bacteria from becoming a

problem. Bactoscan failures arise from one of four causes:

1) Contaminated plant. If the plant is not being properly cleaned then sufficient bacteria will survive between milkings to contaminate the next milking. Just 5mL of milk residue (i.e. a teaspoon) can contain sufficient bacteria to cause a Bactoscan fail of thousands of litres of milk. This is the most common cause of Bactoscan failures

2) Mastitis. Mastitis, especially that caused by environmental streptococci (primarily Strep

uberis), is the second most common cause of

Bactoscan penalties. Cows with Strep uberis

mastitis, even when it is only subclinical, often

excrete large numbers of bacteria so even a

Richard Laven PhD BVetMed MRCVS

Fig 1: Effective cleaning of the milking machine

is essential to maintain low Bactoscans

Fig 2: There should be a standard protocol for

cleaning to ensure that it is done correctly

every time relatively small number of cows can result in

high Bactoscans. 3) Refrigeration failure. If pre-cooling and

refrigeration do not quickly and effectively get

the temperature of the milk below 7oC, the

bacteria that are naturally present in the milk at low numbers will multiply leading to elevated Bactoscans

EBLEX – Improving Beef and Sheep Health 1. Environmental bacteria. Bacteria from the environment, e.g.

from mud, manure, milker’s hands, and feed can contaminate the

teats and, if the teats are not cleaned effectively prior to milking,

can then be transferred into the milk. The risk of this happening

is particularly high if the machine is put onto wet dirty teats Targets for Bactoscan Irrespective of the thresholds set by the dairy company, good

management should be able to keep Bactoscans below 30,000/ mL.

If Bactoscans are regularly > 50,000/ mL then remedial action is

required. Identifying the cause of failure When you get a Bactoscan failure you need to carry out a really thorough plant inspection looking for problems such as milk residue, split liners and cracked or perished rubber ware. If there are no obvious problems then the next step is bulk tank culture. This will identify the type of bacteria which are causing the raised Bactoscan and suggest likely remedies for reducing it. A range of tests is needed – a minimum of standard bacterial culture, coliform count, psychotroph count and thermoduric count (see Box 1). When Bactoscan fluctuates between high and low levels, it is worth freezing a bulk milk sample daily and when another high Bactoscan occurs, sending that day’s bulk milk for further testing. Box 1: Relationship between the cause of high Bactoscans and bacterial culture

Specific bacteria:

a) Strep uberis: Environmental mastitis –

often subclinical, may also be on unclean teats

b) Staph aureus: Mastitis, may also be on unclean teats c) Enterococcus faecalis: Dirty teats d) Pseudomonas sp.: Can be mastitis

but usually contaminated water supply

High psychotroph count: Psychotrophs are bacteria which grow at refrigeration temperatures. These bacteria are found in bedding, so high levels can result from inadequate teat preparation, particularly if the bedding is wet. Psychotrophs can also be high as a result of insufficient cleaning of the bulk tank and/or ineffective milk cooling

High coliforms count Coliforms come from manure, mud and contaminated water. A high coliform count can arise because of mastitis, but the great majority of high counts arise either from poor refrigeration

or, more commonly still, poor cleaning of the milking plant.

High thermoduric count Thermodurics are bacteria which can tolerate

high temperatures.

The most common cause of a high thermoduric

count is inadequate cleaning

of the milking plant. There is often hard milk

residue on the upper surface of the milk lines and

visible residue in the tanks. Less commonly,

thermodurics can arise because of environment-

tal contamination of the teats often from silage.

Fig 3: Cows with even mild cases of

Strep. uberis mastitis can excrete vast

numbers of bacteria greatly increasing

Bactoscan figures

Fig 4: Keeping cows in a clean hygienic

environment will reduce Bactoscan

levels by reducing the risk of mastitis

and by reducing bacterial

contamination of the udder and teats

Fig 5: Maintenance of the refrigeration

system, including the plate cooler, is a

crucial part of milking machine

maintenance

Responding to Bactoscans There are four strategic areas: Plant cleanliness :

Make sure that the cold water rinse after milking removes the majority of milk residues

The plant should be cleaned and disinfected after every milking

and the tank should be rinsed and cleaned after every collection. The milk filter should be inspected and changed after every milking

Ensure airlines are free from dust and milk – split liners are a common cause of milk in airlines

Regular inspection of the plant is essential to ensure there is no build-up of milk residues

Check rubber ware regularly and replace it if it is cracked or perished

• Cow preparation and health Have a consistent routine of teat preparation prior to milking.

Clean soiled teats with a dry wipe if possible. Avoid over-wetting the udder. Pre-milking teat dipping of cleaned teats can significantly reduce Bactoscans.

Check that the water used in the plant is not contaminated If subclinical mastitis is the problem, get a herd test done to

identify the infected cattle. Then stop milking these cows into the tank and treat them with antibiotics.

• Milking routine Wear rubber gloves and disinfect them regularly during

milking. Ensure clusters which fall or are kicked off during milking are

clean before replacing • Milking machine maintenance

Check that the temperature of the milk entering the tank is no

more than 180C, and that of the milk in the tank is below 7

0C

within three hours of milking. This should be done at least 4 times per year

Maintain the milking machine in good working order. Testing

at least once per year is essential

Fig 9: Old liners can be a significant source of bacteria:

Have a regular schedule of replacement and check them regularly

Fig 6: Wearing gloves during

milking reduces the spread of

mastitis and keeps Bactoscan

levels down

Fig 7: Contaminated teats are a

common source of the bacteria

detected by Bactoscan

Fig 8: Clean soiled teats with a dry

wipe if possible

Summary:

Hygienic milk production is essential.

The Bactoscan measures the number of bacteria

in milk o

Automated process o Takes < 7 minutes per sample

Four main causes of failure: 1. Contaminated plant due to poor cleaning 2. Mastitis, especially environmental streptococci 3. Failure to cool the milk quickly and effectively 4. Environmental bacteria from poor

preparation of the udder before

milking

Four areas of response: 1. Plant cleanliness – more inspection and better

cleaning 2. Cow preparation and health –

clean teats, clean water and clean non-mastitic milk

3. Milking routine – clean gloves, clean clusters 4. Milking machine maintenance – test at least once per

year

Mastitis Part 6 – Good Parlour Routine

Richard Laven PhD BVetMed MRCVS

The aim of good milking management is to maximise

production of quality milk, minimise teat end damage and

mastitis- and to make best use of the labour and milking

facilities. Cows love routine. Ideally, the milking routine should be designed so that every cow is milked exactly the same at every milking, regardless of stage of lactation or who is

milking them. The milking procedure should be written and everyone who milks the cows should understand the procedure and the reasons behind it. Only trained staff

who are responsible, conscientious, and have a positive attitude, should be milking cows. The milker needs to be constantly alert to conditions that may spread mastitis

from cow-to-cow or environment-to-cow. Preventing mastitis spread is crucial for producing quality milk. One key area is transmission of bacteria, particularly Staphylococcus aureus, from the milker’s hands to the

udder. Wearing milking gloves is an extremely effective method of reducing bacterial spread. Combining gloves alone, with regular disinfection, such as at the end of each

row, is the gold standard. In a herd with an average incidence of mastitis (30 cases / 100 cows / year), the net benefit of using gloves and disinfection will save around

£1.60 per cow per year; in problem herds the benefit is around £6.10 per cow per year. These are huge savings for very little cost! The next area to focus on is spread from cow-to-cow. Bacteria from infected cows can contaminate the cluster and spread infection to the next 9 cows milked with the same cluster. Milking order can therefore have a major impact on the spread of mastitis. Milking first lactation cows first followed by cows with low somatic cell counts second, cows with high somatic cell counts third- and cows with clinical mastitis last will reduce the spread of mastitis organisms from cow-to-cow. However, active maintenance and management of cell count and clinical mastitis records is essential if milking order is to have an effect. Using milking order to manage mastitis is not simple; it requires commitment and effort. The procedure is probably only practicable in intensively managed small herds (<50 cows), herds which have large cheap labour resources, or in very large herds where separate groups of animals can be maintained for each of these categories. Often, the costs of re-organising an established milking order outweigh the benefits, in a herd with a stable level of

mastitis (ranging from 10 – 40 cases / 100 cows / year), the net loss (benefit in terms of mastitis reduction – cost of time etc.) from setting up milking order on the basis of mastitis is likely to be between £7 and 28 per cow per year – higher for herds with more mastitis. It is likely that the benefits are greatest in problem herds where the level of contagious mastitis (clinical or subclinical) is rapidly rising. A cheaper alternative to milking order is to rinse the clusters with an effective disinfectant after a cow will clinical mastitis has been milked – the benefits of this procedure range from 70p / cow / year in herds with a low incidence to £11 / cow / year in problem herds. However, in the past, rinsing the clusters after milking has not been commonly practiced in the UK - because of the impact on time spent milking. However, cluster rinsing has now been automated and is on its way to becoming a relatively common practice on UK dairy farms. It is important to note that rinsing the cluster after high cell count cows does not work – on problem herds the loss per cow per year of such a strategy is estimated at > £120! Whether you are using milking order to control mastitis or

not, cows at high risk for new intramammary infections

(IMIs) such as fresh cows, fresh heifers, and sick animals should be managed separately, because their milk is not

going to be put in the bulk tank. Newly introduced animals

should be also milked separately until their health status is determined, and the clusters sanitised before and after

milking. Milking preparation should consist of: udder massage, foremilk stripping, washing and drying teats if necessary and then, finally, teat end sanitation before milking if that is

used. Whatever the method of cow preparation, a regular routine is essential. At the end of the preparation period, the teat surfaces should be consistently clean and dry

before the milking machine is attached and milk letdown should have been stimulated. The cups should be applied at or soon after milk ejection when teats are plump with milk. To decrease the spread of bacteria from one cow to

another, single-use cloths or paper towels should be used

to dry the teats of individual cows. Some producers use

individual cloth towels on each cow,

Fig 1: An unhygienic environment leads to an - increased risk of mastitis and lowered milk quality

with towels being

laundered, sanitised and

dried after each milking.

Choose the system that

best fits your routine. To produce quality milk, the milking parlour and milking equipment must be kept as clean as possible throughout milking. An unhygienic environment leads to an - increased risk of mastitis and lowered milk quality (Fig 1) 1 Cow cleanliness also has a great effect on efficiency of teat preparation. (Fig 2) Dirty cows will easily double cow preparation time and, thus, unnecessarily slow down parlour throughput. In a 100 cow herd this can add up to 15 minutes per milking! Ensure that however dirty the udder, only the teats are washed, sanitised and dried. Wetting the entire udder makes it difficult to adequately dry the udder before attaching the cups. An inadequately dried udder can result in drops of dirty water running down onto the teat after it has been sanitised. Milking wet udders and teats is likely to result in an increased risk of mastitis and elevated bacterial counts in bulk tank milk. (Fig 3) Removing a small amount of milk from each quarter of each cow before each milking helps identify new udder infections and improve milk quality. By fore-stripping, abnormal milk can be identified before a

cow is milked and milk is put into the bulk tank. Milk should never be stripped onto the hand as this routine spreads organisms from teat-to-teat and from cow-to-cow. Ideally, fore-stripping should be done on clean teats prior to any teat sanitation. This fore milk should be drawn onto a dark surface such as a strip cup as this makes changes in the milk more easy to see. Prep lag time is the time between beginning teat

preparation and cups on. The range of 60 to 90 seconds is accepted as

the optimal prep lag for all stages of lactation. This

time period allows the cows to be prepared in

batches of 5 or 6 before the attachment of the milking units. Attachment

should be done carefully to prevent excessive air

from entering the milking system. Total milking time is about 5.5 to 8.0

minutes. Longer times are required in herds with

high average production. Although washing and drying helps to reduce bacterial levels, it is by no means as effective as applying a disinfectant (pre-dip) to the teats. Pre-milking teat disinfection means applying a quick- acting disinfectant just before milking to reduce the population of mastitis-causing organisms on teat skin, especially in the region of the external teat orifice. The major effect of pre-milking teat

disinfection is against environmental mastitis, reducing new environmental streptococcal infections and Escherichia coli in the pre-dipped cows by as much as 50%. If superficial teat contamination is the cause of high total bacterial counts (TBCs), pre-dipping will also improve TBCs. Sufficient drying time of the sanitising solution prior to milking is critical. Pre-dipping should be considered if high numbers (more than 5 per 100 cows per month) of clinical cases due to environmental bacteria (for example Strep uberis) are the problem in

the herd or as a control practice in high-risk cows during periods Fig 2: Cow cleanliness has a

great effect on efficiency of teat

preparation

Fig 3: Cleaning dirty

teats before milking

is essential

Fig 4: Alignment is necessary for effective and

complete milking

of high-risk, such as in freshly calved cows after turn-

out in spring. Sanitising solution should remain in

contact with the teats for 30 seconds. In some cases, farmers use standard post-milking disinfectant products as pre-dips, sometimes by diluting the ready-to-use post-dip with an equal quantity of water. This is not advisable because the post-milking teat disinfectants do not have very rapid speed of action and the high iodine concentrations used in post-dips could lead to residues if the product is used as a pre-dip. Lastly, when diluting post-dips to act as a pre-dip such prepared solution is often then used both for pre- and post- dipping. The efficacy of such post dip will be reduced and the new infection rate and herd cell count may start to rise. The addition of an emollient is neither necessary nor desirable for pre-milking teat disinfection. Use a proper pre-dip Milk ejection is initiated by oxytocin, as a result of both conditioned and non-conditioned reflexes and inhibited by the stress hormones, such as adrenaline. The conditioned reflexes include learned responses such as when seeing the milking yard and parlour, moving into the parlour and hearing the sounds of the milking plant. The unconditioned reflexes include tactile responses from handling of the teat such as the calf suckling, udder massage and application of the teat cups. Cows that are frightened or excited before milking may not have a normal milk letdown response in spite of an effective preparation routine. A milking environment that chronically stresses cows may predispose cows to a greater rate of mastitis. The aim of a good milking routine is to maximise the amount of milk removed from the udder at each milking. Improperly aligned units may block milk flow and

increase the amount of milk remaining in the udder at

the end of milking. Milking units, while they are

attached to the udder, must be adjusted correctly to

prevent liner slips. (Fig 4) The unit should be removed as soon as the last

quarter milks out. Removing milking machines from teats can be done either manually or mechanically. Manual removal can lead to over-milking, which can cause teat- end damage and decreased resistance to pathogens. Automatic cluster removers (ACRs) can also lead to over milking, if not set and maintained properly. However, using ACRs generally reduces the probability of over milking. A minute or two of over-milking with a properly functioning milking machine is not a major risk for mastitis. However, the risk of liner slip and possible new infection is greatest during over-milking. The way in which teat cups are removed is usually more important than when they are removed. (Fig 5) The vacuum should always be shut off before teat cups are removed. The practice of pulling the unit off under vacuum should be avoided because it may result in liner slip and infection spreading between quarters. Vacuum shut off prior to removal can be achieved through either bending over the long milk tube or by using the steel clamp on the long milk tube. The vacuum in the claw will then drop slowly as air moves into the claw through the air admission hole in the claw. (Fig 5) After milking the teat ends should be examined for

signs of damage. A normal teat should have healthy

unbroken skin with a white ring. Early teat end

damage shows as small haemorrhages obvious on

white skinned teats. Further progression of teat

damage shows as radial cracking of the white ring,

followed by enlargement of the cracks and thickening

of the ring around the teat end, with the end of teat

canal starting to point outwards. In severe cases,

fronds of tissue form – severe hyperkeratosis. These

lesions indicate that there are milking machine faults

which are damaging the teat end

Fig 5: The vacuum should always be shut

off before teat cups are removed

Fig 6: Excessive machine stripping is one

of the most common causes of teat injury.

Post milking teat sanitation is the single

most important step in mastitis control. It

has been shown in many studies to reduce

new infection rates by about 50%. A good

teat disinfectant destroys organisms on

teats, prevents teat canal colonisation of

organisms, and eliminates existing teat

canal infections. Finally, to reduce the risk of mastitis the

cow must stay on her feet for a minimum

of 30 minutes after being milked. This is to

allow time for the teat orifice to close. This

can be done by offering food at the exit of

the milking parlour. This simple control

method has economic benefits even in

herds with good mastitis control – net

benefit ranging from 50p / cow / year in

good herds to £3 / cow /year in problem

herds. In summary, good milking management

plays important role in the prevention of

mastitis. Excessive machine stripping and

removal of the teat cups too violently

without releasing the vacuum are the two

most common causes of teat injury.(Fig 6)

For cows, milking procedure should be a

pleasurable and routine experience

Copyright © NADIS 2010

Mastitis Part 7 - Teat Disinfection

Fig 1: Teat dipping

Introduction Teat disinfection is the

cornerstone of all mastitis control programmes. Disinfecting the teats after milking (post-milking teat

dipping / spraying) is one of the key planks of the 5-point plan

introduced in the 1960s and, since then, has been shown to be effective in a huge number of studies. Pre-milking disinfection

has not been in use for so long, but is now commonly seen on-farm. There are two commonly used methods of teat disinfection - either dipping each teat separately using a cup filled with disinfectant or by spraying disinfectant onto the teats from below. Whichever method is used, the full benefit of teat disinfection will only be achieved if the disinfectant is applied efficiently and effectively. The two main factors inhibiting the effectiveness of teat disinfection are ineffective formulation and poor application. Problems with product formulation are usually due to either incorrect mixing of concentrate on farm, or to extraneous water getting into a previously prepared mixture. Poor application, i.e. failure to cover the whole teat of every cow at every milking is the most common error in teat disinfection. All the benefits of correct product selection, preparation and handling are lost if the teat disinfectant does not reach the skin of the teat. Proper disinfection is not just disinfecting the teat end but disinfecting the entire teat barrel – that is, everywhere the liner has touched. However, there is no benefit to be gained in disinfecting any other part of the udder surface. Teat dipping is the best method of disinfection, but spraying can be just as effective, if it is carried out

conscientiously.

Pre-milking teat disinfection – what’s the

point? Pre-milking teat disinfection involves applying a quick-acting disinfectant just before milking to reduce the population of mastitis-causing bacteria on teat skin especially in the region of the external teat orifice. The major effect of pre-milking teat disinfection is therefore against those environmental micro-organisms which cause mastitis. Pre-milking disinfection is not aimed at improving teat condition, so the addition of an emollient is not indicated. Pre-dipping reduces new environmental streptococcal infections and Escherichia coli by as much as 50%. Pre-dipping teats should be considered if there are high numbers of mastitis cases due to environmental bacteria (> 5 per 100 cows per

month), or, particularly in spring-calving cows, at high risk periods such as in the first week after calving. Pre-dip should be applied to teats after they have been fore-

milked and then dry-wiped, or washed and dried. Pre-dip needs a minimum contact time of 30 seconds and must be wiped off

prior to the application of the milking units. If you are going to

pre- dip, ensure that you use a registered product and do not

just use your post-milking teat disinfectant. Most post-dips do

not have a very rapid speed of action and their use as a pre-dip

may contaminate the milk. Post-milking teat disinfection – crucial for

mastitis control Post-milking teat disinfection should prevent mastitis and

enhance teat skin condition. –In preventing mastitis, the post-

milking teat disinfection works by

Fig 2: Teat spraying

the removal of mastitis-causing bacteria from the teat

skin and teat sores. Disinfectant should be applied as

soon as the cluster is removed, -while the teat canal

is still open. The dip can then penetrate the teat

orifice, ensuring that those bacteria which have just

entered the canal will also be killed. The main source of mastitis bacteria on the skin of

the teat is the milk from cows with infected quarters. Staph aureus or Strep agalactiae from the milk of an infected cow can remain on the teat cup liners for up to 9 milkings. This means that infection can spread from one cow to the next 9 using the same cluster. Most of the bacteria will be on the teat skin from where they can move into the udder at the next milking. Unless they are removed, bacteria on the skin can multiply (especially at sites of teat lesions) increasing the risk of infection via the teat canal at the next milking. Post-milking teat disinfection, dipping or spraying, removes the bacteria that spread during milking and, as such, is an extremely effective weapon against the spread of contagious mastitis. Any skin lesion which is infected heals very slowly.

Teat disinfection removes bacteria from the skin

surface, thus promoting healing. Rough or chapped

teat skin can also be a reservoir for mastitis-causing

bacteria, so thorough disinfection of the whole teat is

important.

Dipping Dips can be applied by hand-held cups or with a 'power dipper' (a dip cup on a wand with solution applied when a trigger is activated). Dipping uses less product than spraying (approximately 10 ml per cow per milking versus 15 ml, respectively) and, provided that it is carried out correctly, can provide an excellent teat coverage. This application method requires

slightly more time than most spraying applications when taking preparation, refilling and actual application into account. Cups should be emptied before refilling, rather than 'topped up' when the solution becomes low and any solution remaining at the end of milking should be discarded. The cup should be large enough to accommodate the teat without causing excessive spillage of the disinfectant solution. The act of immersing each teat in a reservoir of disinfectant usually ensures the entire teat barrel (any area in contact with the teat liner) will be covered, as long as the cup is deep enough and filled with the appropriate amount of an effective solution.

Spraying Spraying requires more disinfectant than dipping to achieve the same degree of teat cover because spray will also be applied to the udder. Sprays can be applied using a gun-type hand piece with a spray nozzle or a fully automated spray system. Teats should be sprayed from below using a circular motion to cover all sides of all teats. The drawback of spraying is that there is a much greater chance of achieving only partial teat cover than when dipping. The absence of disinfectant on the other side of the

teat could allow the establishment of a reservoir of

mastitis-causing bacteria. Partly blocked spray

nozzles can also result in poor teat cover. Fully-automated teat disinfectant spray delivery systems are available. Infrared light beams activate spray nozzles and spray patterns are adjusted to the average cow's udder. Although they can save time and man-power, most automatic units will not give as consistent teat coverage as manual spraying

Fig 3: Automatic teat sprayer

Fig 4: Teat spraying – checking

the coverage of teats using paper towels

Fig 5: Dirty teat disinfecting

equipment will spread disease

Teat disinfection products

More than 10

different active

ingredients have

been used in teat

disinfectants

throughout the world over the past 30 years. The

most commonly used active ingredients are: iodine, chlorhexidine, quaternary ammonium compounds,

hydrolysed fatty acids, hypochlorite, and acid anionic

compounds. Teat skin has relatively few sebaceous glands and continual washing followed by exposure of damp teats to a cold and windy environment can remove protective fatty acids and lead to cracking. Hence, emollients are added to the disinfectant preparations. The addition of emollients, such as glycerine, sorbitol, lanolin or propylene glycol, to teat disinfectant can improve teat skin health and so reduce the likely reservoir of mastitis bacteria in teat sores and cracks. Many teat disinfectants contain emollients when they are sold. Addition of excessive amounts of any

emollient (i.e. >20%) will most probably reduce killing activity and could lead to increases in the new mastitis. For effective teat disinfection always:

1.Read the label and follow the instructions on

dilution rates, water quality requirements, mixing

procedures, shelf life, compatibility information,

and storage conditions. 2.Prepare fresh disinfectant for use (not older

than 3 days), and this should be stored in a

container with a lid so that extraneous water will

not find its way into the already prepared

solution thus diluting it.

3.Regularly clean the equipment (minimum once a

week).

Poorly prepared disinfectant applied with dirty and

contaminated equipment can be a source of new

mastitis infections

Summary

Teat disinfection is an important measure in mastitis control.

It can be carried out pre- and post- milking or by a combination approach.

Pre-milking teat disinfection controls environmental mastitis (i.e. Strep uberis).

Post-milking teat disinfection controls contagious mastitis (i.e. Staph aureus).

Teat disinfectants can be applied by dipping or spraying.

Application by spray can be as effective as dipping when applied properly and consistently.

Dipping requires less disinfectant, but more time.

Addition of emollients to the teat disinfecting solution can improve teat skin health.

Equipment must be regularly cleaned. Otherwise it can act as a source of mastitis bugs.

Mastitis Part 8 – Dry Cow Therapy The dry period is an essential part of a cow’s lactation cycle. This period allows the lining of the udder to be repaired and restored,

so that when lactation starts again, milk production is optimal. A dry period of at least 40 days is needed to get optimal milk

production. If it is shorter than 40 days, milk production will be

reduced. The dry period has three stages: 1) Involution – after daily milking stops, milk secretions change

and finally dry up. The- lining of the udder regresses (reduces in activity and gets smaller) and the teat canal becomes plugged with keratin. This period lasts approximately two weeks.

1) Steady state – after involution the udder stops changing and there is no active secretion of any product. The length of this period depends on the length of the total dry period as the length of the other two periods is fixed – it is - during this steady state period, that the recovery occurs which allows maximal future production of milk. Shortening it to <2 weeks will reduce milk production.

2) Colostrum production and start of lactation – the

machinery of lactation is switched on, the udder starts to

enlarge and the lining becomes active. This period lasts

around two weeks.

Tackling infection As well as being essential for the recovery of the mammary gland,

the dry period offers an opportunity to tackle udder infection. The recovery process, alone, will eliminate some infections, but it is much more effective when combined with antibiotic treatment. In fact, particularly for subclinical udder infections, the most effective

time to treat is at drying off because: 13. Higher doses can be used than in the milking cow

14. Antibiotics remain in the udder for longer – compared to the

milking cow where a lot of antibiotic is lost at each milking. Antibiotics used for dry cow therapy are different from those used

in the milking cow – they have a high concentration of –antibiotics

in a slow-release base. This means that the cure rate for dry cow

therapy is much higher than for milking cow therapy, especially for bacteria such as Staph aureus. An - advantage of dry cow antibiotics, which is often not

appreciated, is that clearing infections – even mild ones – can aid

recovery of damaged mammary tissue and aid the speedy

formation of the keratin plug of the teat canal.

Preventing new infection: Dry cow therapy is not just about tackling existing infection. A -

second aim is in preventing new infection during the dry period.

Even though it is not being milked, the udder can get infected

during the dry period. However, each of the three stages has

different risks for mastitis. During the steady state the risk is low,

but after drying off and immediately before calving, the risk increases dramatically (see Figure 1)

Fig 1: Effect of dry period stage on risk of mastitis

Fig 2: The dry period is essential for repair of the

mammary gland - In addition to treating existing infections, dry cow therapy has to prevent new ones. This is simple in the early dry period, as the high –concentrations of antibiotic which treat infections will also prevent new ones. However, in the period before calving, antibiotic -concentrations will be lower and the risk of infection is higher. This is particularly the case for cows with a dry period longer than the active period for the antibiotic – which, in products available in the UK, ranges from around 4 to over 10 weeks. To make matters more complicated, the infections that dry cow

therapy has to prevent tend to be different from those it has to

treat. Staph aureus is the most important bacteria to kill, as this is

the organism which causes most persistent infections. In

contrast, dry cow infection, especially in the late dry period, tends

to be caused by environmental organisms, such as E. coli and

Strep uberis. Dry cow antibiotics tend not to be equally effective

against all three bacteria, so choice of antibiotic should always be

made based on the bacteria causing the problem. The benefits of effective prevention of udder infection during the

dry period do not just apply to the immediate dry period and very early lactation. Studies have shown that dry period infection can

lead to mastitis up to three months after the cow has calved, so preventing new infections in the dry period is crucial in controlling

mastitis. Which antibiotic There are a range of products available from your vet. The best

antibiotic will vary from farm-to-farm and often cow-to-cow and

year-to-year. There is no simple answer. The key factors to look

at are: 7) Length of action – if you have long dry periods then products

with a long action may be beneficial, but if you have short dry periods then you will not be able to use most long-acting products

8) Environmental vs. Contagious mastitis. If the problem is the former, then preventing infections is key so use an antibiotic with activity against Strep uberis and E coli. If the latter, then you may benefit from sacrificing activity against environmental organisms by choosing an antibiotic specifically designed to kill Staph aureus.

Choice of dry cow antibiotic should not be based on an automatic

‘same as last year’ or ‘whichever’s cheapest’, but a carefully

thought out process based on current information.

Whole herd vs. Selective Dry Cow Therapy In the UK, most herds use blanket therapy of all cows at drying

off. The advantages of this- are that all infected quarters will be

treated and all quarters will be protected from new infections

during the early dry period. However, blanket therapy means that cows without infection, which will also have a low risk of new infections in the early dry period, are given antibiotics. Selective dry cow therapy based on cell count and mastitis history can be used to reduce the number of treated cows, but, -whichever criteria -is used, it is likely that some infected cows will not be treated, and, overall, on an economic basis, blanket therapy remains the best choice in most herds. Antibiotic alternatives The formation of the natural keratin plug during the dry period is

key component of the cow’s natural protection against udder infection. However, not all cows will form a plug that is effective throughout the dry period. Artificial internal teat sealants have

been developed which can overcome the absence of the keratin plug. If used alone in uninfected cows, internal teat sealants will reduce the risk of new.

infections during the dry period – they are at least as good as

antibiotics in doing this. In infected cows they can be combined

with –antibiotics and will significantly reduce the risk of new

infections in the later dry period, particularly in cows which are

dry for longer than the active period of the antibiotic. An alternative to internal sealants are persistent external teat

dips, which protect against new infection by covering the teat end

with a disinfectant. However, as yet, we do not have products

which Fig 3 Clean the teat end

with teat wipes

Fig 4 Partial insertion of the antibiotic tube (< 6mm)

Reduces the risk of pushing

infection into the udder at drying off

persist for long enough, most require a new application every 5 to

7 days. Preparation of the cow for drying off Cows should be producing <15L of milk / day when dried off. This figure should be achieved by a gradual reduction in feed intake, not by reducing water availability. Once the figure has been reached the cow can be dried off -abruptly. Inserting the drying off tube should be a separate operation to milking and should be carried out after the last milking. The cow should also be separated from the milking herd to break the routine of the milk let down reflex. Dry Cow Treatment Procedure If done badly, dry cow treatment can result in udder infections and

mastitis. These infections often cause extensive udder damage

and can be extremely difficult to treat. Attention to detail and strict hygiene precautions are essential to prevent such infections. This

is especially important if an internal teat sealant is going to be used without antibiotics. All staff carrying out dry cow treatment should be familiar with the

procedure and know how essential it is to follow it:

Copyright © NADIS 2010

• After milking for the last time, separate the cow

off and dry her off after that milking has finished • Starting with the teats on the far side of the

udder – clean the teat ends with separate teat

wipes. Focus on the teat end not the udder

• Move onto the teats on the near side of the

udder and clean those • Then starting with the teats on the near side of

the udder, infuse each quarter with antibiotic.

• Insert the antibiotic tube just into the teat

canal (<6 mm)

. Insert the whole of each tube into teat

. Massage the treatment up into each quarter . Immediately following treatment, dip all teats

in an effective teat dip

Mastitis Part 9 - The Milking Machine Simply milking a cow does not result in mastitis. When functioning according to the manufacturer’s specifications and operated properly, the milking machine should not cause mastitis. Indeed, it has been difficult to produce mastitis by simply altering machine function. Yet the machine is often blamed for an outbreak when other aspects of milking management are primarily responsible. Nevertheless milking machine management is a crucial component of mastitis control, and it is essential that the effects of the milking machine on mastitis are well understood by farmers, dairy advisors, milking machine testers and veterinarians.

How does the milking machine increase mastitis?

1. Physical transport of bacteria between quarters and

between cows Within any herd there is a mixture of cows, some with healthy udders and others with either clinical or subclinical mastitis. The infected cows are likely to shed mastitis-causing bacteria in their milk. Additionally, teat surfaces might be contaminated with bacteria from the environment (e.g. coliforms, Streptococcus uberis) or these present in teat sores and other skin lesions of the udder (e.g. Staphylococcus aureus, Str. dysgalactiae). The milking process offers two main opportunities for mastitis-causing bacteria, to be transferred - between the quarters of a cow and between cows. Vacuum fluctuations in the claw result in reflux and moving of milk between the cups. If the cow being milked has one or more infected quarters, this process may transfer bacteria to the other teats or quarters. Milking machine modifications designed to prevent inter-quarter transfer, such as multi-valve or ball claws, do contribute to mastitis control. Nevertheless whatever claw system is used, without flushing between cows, milking an infected cow will contaminate the

milking machine liner surfaces for the next 6-9 cows. 2. Teat skin and end damage Milking machines can affect udder health by reducing the natural resistance of the cow, to mastitis. Teat sores and cracks provide sites where mastitis-causing bacteria can multiply and hide before invading the udder to cause mastitis. Damaging the teat is probably the main route by which milking machines influence the level of mastitis. Common machine problems of the milking system associated with teat damage are pulsation failure, high vacuum, vacuum fluctuations, liner defects, liner slip, and long-term over-milking. Teat conditions resulting from these problems include eversion, hyperkeratosis, haemorrhagic blisters, teat chapping and blackspot Damaged skin is readily colonised by mastitis-causing bacteria,

particularly Staph. aureus and Strep. dysgalactiae. The regular

use of a teat

Richard Laven PhD BVetMed MRCVS

Fig 1: Teat ‘rings’ caused by faulty milking machine

Fig 2: Impact – how bacteria from one quarter can get

into another quarter during milking

Fig 3: Kicking off clusters increases the risk of mastitis

spread

disinfectant with added emollient, alongside regular milking

machine maintenance can reduce skin damage and aid the

healing of the lesions. If the cow is going to experience pain during the milking process

because of a faulty machine, she will be restless in the parlour

and will not let her milk down readily. This can lead to incomplete

milking out. 3. Reverse flow of milk

Mastitis-causing bacteria entering the udder at the beginning of milking are more likely to be flushed-out during milking than those entering during the removal of the milking unit. The reverse upwards flow of milk when there is a sudden admission of air into the system (resulting from a wide range of factors including liner slip, sudden vacuum fluctuation, improperly aligned clusters, improper application/removal of teat cups, vigorous machine stripping and liner kink) may result in milk jets (impacts) from the cluster onto the firmly attached teats. Milk droplet impacts can be minimised by avoiding abrupt vacuum loss, particularly at cluster removal. Selection and care of shells and liners (Inflations) For maximum milking and udder health the liner must match the teat cup shell. Teat cup liners are usually made of synthetic rubber with a porous surface. Such a surface is susceptible to filling with milk fat and other solids. Cracked or damaged liners are difficult to clean and disinfect. They act as reservoirs for mastitis-causing bacteria and do not function properly during milking. Therefore, liners should be discarded when the number of uses recommended by the manufacturer is reached. Liners should also be discarded when they lose shape and become rough or cracked. When one liner is discarded, the others in the same set should also be changed. Alternative materials such as silicon rubber, which is not porous, are likely to be longer-lasting. Liner Slip Liner slip occurs when the liner loses contact with the teat skin

and permits entry of air into the milking system. This causes a sudden drop in vacuum pressure, facilitating reverse flow and

impacts and increasing the risk of mastitis. Liner slips occur with

greater frequency near the end of milking. Slipping in late milking is commonly caused by poor cluster

alignment, uneven weight distribution in the cluster or poor liner

condition. Liner slipping early in milking often results from a low

vacuum level, blocked air vents or restrictions in the short milk tube that lead to overloaded clusters. The percentage of slips may

be enhanced if the teats are not dried properly before milking. Over-milking Over-milking is almost universally regarded by advisors as a key factor in machine-induced mastitis. However, only long-term over-milking has a real impact on mastitis on its own. Long periods of over-milking are known to increase teat damage. Over-milking combined with other faults such as vacuum fluctuations or inadequate pulsation can exacerbate already existing problems, probably by giving a greater exposure of the teat to bacteria and by increasing teat damage. Conclusions Proper maintenance and operation of any milking system is a key aspect of successful milking. Good mastitis control requires more

than good milking machine design and function; it also demands

high levels of hygiene and milking management. In general the milking machine will not influence mastitis occurrence on-farm if:

3) The milking equipment selected for a particular farm

operation is that which is best suited for the management,

labour, and physical facilities available. 4) The system is properly installed according to

manufacturer's recommendations with the primary concern

being that of an efficient milking operation that does not put

unnecessary stress on the cows. 5) The system is properly functioning at a constant

recommended vacuum level. 6) The complete milking system is regularly maintained,

tested as recommended, and faults corrected. Regular replacement of rubberware before it perishes, repairing the faults as detected at the milking machine testing (twice a year recommended), and regulator, pulsators, vacuum gauge checks

will result in efficient milking and a lower risk of mastitis. Regular milking machine maintenance is a key component of maximising farm profitability.

Summary

- The milking machine is unlikely to influence mastitis occurrence on a farm if it is installed, operated, maintained, tested, and

functions according to international standards.

- The milking machine can influence the level of mastitis on-farm by increasing physical transport of bacteria between quarters and

between cows, damaging teat skin and end, and by producing reverse milk flow.

- Liner slips may be decreased by proper attachment/removal of the unit, avoiding machine stripping, and having clean air admission holes

and sound rubberware.

- A properly working milking machine will enhance farm profitability.

Mastitis Part 10 –

Environmental Mastitis

What is environmental mastitis? Environmental mastitis is mastitis caused by bacteria which spread primarily outside of the milking parlour. This doesn’t mean that they don’t spread during milking. Just like with contagious bacteria, infected cows can contaminate the cluster and spread infection to other cows during milking. However, unlike contagious bacteria, preventing cow-to-cow spread during milking will not eliminate environmental mastitis. This is because parlour management does not tackle spread from the environment to the cow. To control environmental mastitis - an added focus on environmental hygiene as well as parlour management is needed. Parlour management, alongside dry cow antibiotics, has been effective -in reducing contagious mastitis but our control of environmental mastitis has been much less effective, so that environmental mastitis now accounts for more than 50% of mastitis cases in UK cattle. All farms need to include environmental management in their mastitis control plan. The two most important bacteria in this group are E. coli and Strep

uberis. Of the two bacteria, Strep uberis is the one that spreads more easily during milking, while E. coli is the one that is most commonly associated with severe toxic mastitis. However, some strains of E. coli can also be spread very well during milking and the

majority of mastitis caused by E. coli is mild in nature Where does environmental mastitis come from? A contaminated environment! E. coli comes from the gut, so anywhere where cow faeces can come into contact with the udder, will provide- a potential source of coliform mastitis. Clearly, bedding is the most important source, particularly organic bedding where the bacteria can grow and multiply. However areas around feeding or water troughs are also risk areas as slurry around these can get splashed onto the udder. Outside of the udder, Strep uberis is also found in the intestines but, compared to E. coli, it is much more commonly found elsewhere on the cow, particularly the skin. Strep uberis has a fantastic ability to develop outside of the cow, particularly in straw. Both E. coli and Strep uberis, particularly the latter, can also cause environmental mastitis in cows on pasture as they can survive for months in contaminated wet mud. Non-organic bedding, such as sand, doesn’t support the growth of

either E. coli or Strep uberis, so the use of such beds can reduce the

risk of mastitis. However, these beds need to be kept clean as there is more -than enough organic material in a single faecal pat to

support exuberant bacterial growth. The peak time for infection with new environmental mastitis-causing

bacteria is the dry period. Infection during the dry period is often

inapparent until the cow develops mastitis after calving. –In order to

control environmental mastitis, we have to focus on environmental

management throughout the cow’s lactation cycle. Preventing

environmental Fig 1: Good clean housing

reduces the risk of

environmental mastitis

Fig 2: Good clean pasture

also reduces the risk of Fig 3: Acutecoliform mastitis

leads to very sick cows

contamination in the dry cow is just as, if not more than, important

as it is in the milking cow. How do you control environmental mastitis? a) Hygienic environment

Indoors:

i. Avoid keeping cows in damp filthy conditions.

6) Adequate, clean, dry bedding is essential – replace daily. 7) Cubicle comfort and design – Are the cows using cubicles

properly, and not defaecating in them. 8) Avoid overcrowding, particularly in straw yards. Pasture:

15. Avoid overgrazing and overstocking. 16. Ensure shade areas (around trees) are large enough to

not become too contaminated 17. In wet conditions, ensure cows are in well drained

paddocks 18. Pay particular attention to management around troughs

and feeding areas Calving

i. Cows should calve in a clean and dry environment.

Indoors - ensure plenty of fresh bedding for every cow Outdoors – choose calving paddocks carefully, don’t

overstock

b) Dry cow therapy Dry cow therapy will reduce the risk of new environmental infections, particularly in cows with a history of mastitis or high cell counts (see bulletin 8). However, the protection against infection provided by dry cow antibiotics at the end of the dry period is not as good as it is at the beginning, especially in cows with a dry period of >6 to 10 weeks (depending on the dry cow used). In such cases, the use of an internal teat sealant can be especially beneficial as this prevents new infections, from the time of insertion, until the cow is milked for the first time. c ) Vaccination In herds with a significant mastitis problem due to E. coli, the use of a J5 vaccine has been shown to reduce the incidence and,

particularly, the severity of the disease. Such vaccines are used

widely in the US, but, although they have been used in the UK, they are not currently available here. Even if they do return , you need to

remember that such vaccines

Copyright © NADIS 2010

Fig 4: Dirty udders spread environmental mastitis

Only work for E. coli and not Strep uberis and are no substitute

for good environmental management d) Good milking routine Although environmental bacteria spread outside the parlour, good milking management will reduce environmental mastitis. For example, ensuring teats are clean before milking, foremilking to detect early mastitis cases, keeping teats in good condition, and reducing impacts by good cup removal technique will all reduce the level of environmental mastitis, particularly that caused by Strep uberis. So having environmental mastitis does not mean that you need to pay less attention to your milking regime. One important change to the milking routing which can reduce the

spread of environmental mastitis, is adding pre- milking teat dipping to the protocol (See bulletin 7).

There are several commercial dips available on the market but you must - ensure that you use a dip designed for pre-dipping and

allow 30 seconds contact time before you dry the teats.

e) Good recording of cases - Proper mastitis records with good bacteriology are essential to tackling an environmental mastitis problem. Always take a milk sample from cows with mastitis before treating them for the first time, freeze it and when you have a problem you have a selection

of samples available to test. Without good information, individualized targeted control programmes cannot be developed fo your farm.

NADIS seeks to ensure that the information contained within this

document is accurate at the time of printing. However, subject to the

operation of law NADIS accepts no liability for loss, damage or injury

howsoever caused or suffered directly or indirectly in relation to

information and opinions contained in or omitted from this document. To see the full range of NADIS livestock health bulletins please visit www.nadi.org.uk