ABSOLUTE HORSE JANUARY 2013 4544 ABSOLUTE HORSE JANUARY 2013

lthough not permitted inbreeding Thoroughbreds,artificial insemination (AI)

has in recent years become a verypopular and routine procedurefor breeding sports and heavyhorses. Health and safety benefits are wellrecognised and conception rateswith fresh or chilled semen canoften equal or exceed expectationsfrom natural service. The process involves monitoringthe oestrus cycle of the mare to bebred and inseminating her close toovulation with either freshlycollected semen, fresh chilledsemen or frozen semen. SuccessfulAI depends on a detailedunderstanding of the mare'soestrus cycle, a comprehensiveunderstanding of the mare’sbreeding history and in some casesthe use of advanced reproductivetechniques. Before launching into breedingfrom a mare, new breeders shouldconsider the reasons for breedingfrom their favourite animal andhow they are going to manage the

pregnancy, birth and rearing ofthe foal. It is well worth seekingadvice from experienced breeders,breed societies and veterinarysurgeons. Breeding can be acostly endeavour. It’s worthsetting a budget based on threeoestrus cycles when committingoneself to such a venture.

Initial assessmentBefore breeding your mare, a fullreproductive examination shouldbe carried out by your veterinarysurgeon to assess her suitabilityfor breeding and to highlight anypotential problems. A fullreproductive history of the mare isvery useful, as this will enableprompt initiation of treatmentprior to or after insemination ifrequired. If insemination is to beperformed at an AI centre, oftenclitoral swabs for contagiousvenereal disease will be requiredalongside blood samples forinfectious disease prior toentering the centre. This is aroutine requirement for all majorinsemination centres across the

country.An initial reproductiveexamination will allowassessment of the stage of youmare's oestrus cycle and willdetermine timing of repeatedexaminations prior toinsemination. Your veterinarysurgeon may take an endometrialswab and smear from your mareat this stage to determinewhether there is a requirement forpre or post breeding intrauterinetreatment such as antibiotics.

Follicular activity is followedclosely alongside otherparameters and when the folliclehas reached a suitable size forbreeding, hormones will be givento induce ovulation.

Fresh, chilled or frozensemen?

Semen may be available eitherfresh, chilled or frozen andmanagement of the mare andtiming of insemination will be

determined by which semen ischosen. For fresh or chilledsemen, conception rates arehighest when insemination isperformed within 24 hourspreceding ovulation. Frozen-thawed semen has a relativelyshort life span and thereforerequires that mares beinseminated immediately before(within 6 hours) or after (within 4hours) ovulation. Subsequentmanagement of mares forinsemination with frozen-thawed

semen is more intensive andmares require multiple ultrasoundexaminations to assess the correcttime for insemination. Per(oestrus) cycle conception ratesfor mares using frozen-thawedsemen are often lower andtherefore ideally this should bereserved for mares with the bestreproductive histories.Insemination with chilled semenrequires good communicationwith the stallion stud so thatsemen is delivered on time.Beware of bank holidays andweekends when using commercialcourier services!

Semen Collection andProcessingSemen is collected from thestallion by the use of atemperature controlled artificialvagina. The collection isperformed with the use of either a‘phantom’ or ‘live’ mare. If a livemare is used, she will stimulatethe stallion, who will then beallowed to mount her. Once thestallion has mounted, thestallion's penis is inserted into theartificial vagina which has beenwarmed to an internaltemperature of approximately 44degrees Celsius. The stallion thenejaculates into the artificial vaginaand the semen is taken to thelaboratory for processing. Manystallions can be trained to mounta phantom mare withoutrequiring prior stimulation by alive mare. Once in the laboratory, the gelfraction is removed from thesperm-rich portion of theejaculate. The sperm is examinedunder a microscope for motility(movement), as well as for anyobvious abnormalities. The

concentration of sperm cells isthen determined. A warmedextender or substitute carrier isthen added to the semen sampleto maintain its viability. Theextended sample is then eitherdivided into doses and distributedfor insemination, or is furtherprocessed if it is to be frozen. It isvery important to prevent largetemperature changes of thecollected semen. Temperaturesthat are either too hot or too coldwill affect the viability of thesperm and may even kill it,resulting in the loss of its fertility.Overexposure to direct light willalso damage sperm cells.

InseminationWhen your mare is ready forinsemination, her perineum andvulva should be thoroughlycleaned and the semen should beprepared. Using a sterile glove, thesemen is inseminated through thevagina into the uterus via auterine catheter. Semen may bedeposited into the uterine body orinto the horn of the uterus on theside where the ovulation willoccur by deep intrauterineinsemination. Occasionallyadvanced techniques such as lowdose insemination or endoscopicguided insemination are used.This is mainly performed in eitherproblematic mares or mareswhere only a small volume ofsemen is available. Following inseminationFollowing insemination, yourmare will be checked for ovulationand for post-breedinginflammation in her uterus. Suchinflammatory responses are morelikely when frozen semen is used.Treatment may be requiredfollowing insemination, especially

in older or problematic horses.Providing all is well, your mare willbe scanned at 16 days followingovulation and if pregnant, it isadvised that scans be performed at28 and 45 days to make sure thepregnancy is developing normallyand to avoid missing the presenceof twins. An older or problematicmare may require treatment tomaintain her pregnancy.Supplementing the mare’s dietwith daily doses of artificialprogesterone (Regumate) isthought to have a supportiveeffect on the pregnancy in somecases.

Problematic maresMaiden mares, older mares ormares with predisposingreproductive problems may find itvery difficult either to conceive ormaintain their pregnancy.Advanced techniques may berequired in these cases prior to,during and followinginsemination. These might includerepeated uterine treatments withsterile saline fluid and antibioticsolutions accompanied bystitching of the vulva to preventinfections entering thereproductive tract. These cases canoften be hugely time consumingand costly, however, if successful,they are usually the mostrewarding to get in foal.

Code of PracticeThe British Equine VeterinaryAssociation (BEVA) provides a listof equine practices that complywith the ‘BEVA Guide to the Useof Artificial Insemination in HorseBreeding’ and their facilities

ROSSDALES EQUINE HOSPITAL & DIAGNOSTIC CENTRECotton End Road, Exning, Newmarket, Suffolk CB8 7NN. www.rossdales.comVetwatch Vet Profile

Name: Chris PhillipsQualifications: BVetMed,CertAVP, MRCVSYear of Qualification: 2005

Chris graduated from the RoyalVeterinary College in 2005. Hethen spent a year in first opinionpractice in Gloucestershire beforeundertaking an 18-monthinternship at Rossdales. This wasfollowed by a stud internshipunder the supervision of Rossdales’former Senior Partner, ProfessorSidney Ricketts. He subsequentlycompleted a southern hemispherestud season at Windsor Park Studin New Zealand.Chris is currently a reproductiveand ambulatory veterinarysurgeon at Rossdales and spendsmuch of his time undertakingartificial inseminations (AI) withfresh, chilled and frozen semen ata large local AI stud. He isadditionally involved in embryotransfer procedures at RossdalesEquine Hospital and, togetherwith colleagues who specialise inreproductive techniques, he hasdeveloped the practice’s semenfreezing service and the Defra-approved dedicated semenfreezing laboratory.In 2011, Chris was awarded theprestigious Certificate in AdvancedVeterinary Practice, focusing onequine soft tissue surgery, by theRoyal College of VeterinarySurgeons (RCVS). He isparticularly interested in stallionreproduction, especially sub-fertility examinations, and isplanning to help further developthis area of the practice.

Artificial Insemination

Frozen-thawed semen must be inseminatedimmediately before (within 6 hours) or after(within 4 hours) of ovulation.

Semen is collected from the stallionin an artificial vagina

Chris Phillips performinga deep horn inseminationin a mare at RossdalesEquine Hospital

By Chris Phillips BVetMed, CertAVP, MRCVS

A

Rossdales Equine Hospital & Diagnostic Centre(Referrals)

Cotton End Road, Exning, Newmarket, Suffolk CB8 7NN. Tel: 01638 577754 (Office hours); Tel: 01638 663150 (24 hours)Email: hospital@rossdales.com

Rossdales Equine Practice(Ambulatory Practice, Pharmacy and Accounts)

Beaufort Cottage Stables, High Street, Newmarket, Suffolk CB8 8JS. Tel: 01638 663150 (24 hours) Email: practice@rossdales.com

permit the correct handling andinsemination of equine semen.In order to prevent the nationaland international spread ofvenereal diseases by artificialinsemination and obtain optimalconception results for their mares,breeders are strongly urged to usethe services of practices thatcomply with the BEVA AI Scheme.

Rossdales has been approved byBEVA to provide AI services andour veterinary surgeons haveperformed many successfulinseminations, ranging fromstraightforward mares to morecomplex cases. We offer acomprehensive AI service to ourclients and referring veterinarypractices. Our Defra-approvedsemen laboratory uses the latestequipment and techniques forfreezing, storage and shipmentof semen to all major marketsaround the world. To speak to one of ourreproduction experts, contactthe practice on 01638 663150.