adverse reactions to food. are they worth investigating
TRANSCRIPT
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Adverse Food Reactions- are they worth
investigating?
Anthony Chadwick BVSc CertVD MRCVS
The Webinar Vet
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In my Liverpool home
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• Qualified in 1990
• CertVD in 1995
• Set up The Webinar Vet in 2010
• Sold first opinion practice in 2011
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The Story of Rosie McCartney
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The Take Home Messages
• Food Allergy/Intolerance is an important cause of
skin disease in dogs and cats
• Food Trials are difficult to do well
• There are often other components contributing to
the itch
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Outline of Talk
• Some definitions
• Aetiology and Pathogenesis
• Clinical Signs
• Diagnosis
• Treatment
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Definitions
• Adverse reaction to food
• Food allergy reactions
• Food intolerance reactions
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Atopic dermatitis and food allergy in humans
• Numerous studies show a clear relationship between food allergens and the development of AD
• Often food allergy seen in infants and young children
• Just under 40% of AD cases will have concurrent food allergy
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Aetiology and Pathogenesis
• Not fully elucidated in dogs
• A subset have an IgE mediated food allergy
• Also type III and IV
• However vast majority no immunological cause
found
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Aetiopathogenesis
• Puppies who have a poor start to life
• Intestines damaged by virus or worms. Protein allergens can gain access systemically
• Histamine releasing factors continue to be active long after offending allergen removed
• In older dogs sensitisation to an antigen may follow a long refractory period of upto 2 years before clinical signs are present
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• In 80% of cases only 1-2 allergens involved
• Common allergens include: beef, soya, chicken,
milk, corn, lamb, wheat, eggs and lamb
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How long should you perform a food trial for
• 7 days
• 21 days
• 28 days
• 42 days
• 84 days
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What % of your allergic pets have a food
component
• Less than 5%
• 5-10%
• 10-15%
• 15-20%
• More than 20%
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How common is Adverse Reaction to Food
• 30% Chamberlain
• 3% Kunkle
• 2% Carlotti
• 13% Saridomichelakis
• 23% Jackson
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Clinical Signs
• Food allergy can develop at any age
• I see 2 subsets: very young and 7 plus
• Labradors predisposed
• Abyssinians also
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Clinical signs 2
• Non seasonal pruritus
• Recurrent pyoderma
• Similar distribution to atopy
• angioedema
• Otitis
• Concurrent GI signs
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Clinical signs in cats
• Miliary dermatitis
• Symmetrical alopecia
• Head and neck pruritus
• Eosinophilic granuloma complex
• Concurrent GI signs in about 30% of cats
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Diagnosis
Food Trial!
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Food Trialling
• 4-12 weeks required
• Home prepared
• Unusual protein source
• Hydrolysate
• All non seasonal pruritus should be food trialled
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Hydrolysed Proteins
Mast cell
degranulation
Allergenicprotein
Histamine
IgE
Sensitised mast cell
Polypeptides (HYDROLYSATES)
Intactprotein
Enzymatichydrolysis
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Hydrolysed Proteins
Mast cell
degranulation
Hydrolysed
proteins
No crosslinking – no degranulation
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26© Royal Canin SAS 2012. All Rights Reserved.
Extreme hydrolysation:
• Low molecular weight feather
hydrolysate
• In an overall diet analysis, 95%
of the diet is less than 1kDa
EXTREME HYDROLYSIS
Independent analysis of final product
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Alternative tests
• Intestinal permeability
• Gastric provocation
• Colonoscopy provocative test
• Intradermal skin test
• Patch test
• Serum IgE testing
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Food Challenging
• Feed all old diet back again
• Response usually rapid but upto 3 weeks reported
• Then individual ingredients
• Dairy relapse in 4 days, cereal 8 days(Harvey)
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Treat other clinical signs
• Malassezia
• Pyoderma
• Otitis
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How much allergen is too much?
• Jackson’s beagle colony reacted to 1g of corn
• Some animals may be less sensitive
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Are the diets sufficient for lifelong use?
• Anallergenic
• Hypoallergenic
• Home prepared diet
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My plan for non-seasonal pruritus
• Treat infections
• Food and flea trial
• See back in 4 weeks
• Continue food trial if some improvement, possibly skin test
• Food challenge at 8 weeks
• If positive try individual allergens
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Vets South offer
• All my topics on slide share and access at The
Webinar Vet
• £1 membership offer
• Access to pet webinars
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Thanks
Vets South team
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Any Questions?
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