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GENERAL ARTICLETERMINATION OF PREGNANCY IN BITCHESAbhilash.R.S, Anil kumar.K, Biju.S and Ajith.K.S,Livestock Research Station, Thiruvazhamkunnu, PalakkadJ. Ind. Vet. Assoc., Kerala. 10 (1)INTRODUCTIONTermination of pregnancy is one of the mostcommon requests from dog owners. The usualreasons include too young age, too old age,disproportionate size of mating partners or unwantedor accidental mating. Over the last 20 years manynew drugs have been used for termination ofpregnancy in canines. There are different treatmentprotocols such as oestrogen therapy, PGF2 and itsanalogues, dopamine agonists, combination ofprostaglandins and dopamine agonists, anti progestintherapy etc. Although most of these drugs havealready been used for years in other species, only feware widely marketed or approved for use in dogs. Theaim of the present article is to briefly review the stepsto be taken before proceeding with termination ofpregnancy, the drugs available for the termination ofpregnancy in bitches, their pharmacologicalproperties and availability.INITIAL EXAMINATIONA thorough history is valuable prior toattempt termination of pregnancy in bitch. Confirmwhether the animal has actually mated or not. Avaginal smear is the best diagnostic tool forevaluating mating and to find the stage of the cycle.The presence of sperm or sperm head confirmsmating whereas absence of sperm does not indicatethat a fertile breeding did not occur. Pregnancyshould be confirmed by ultrasound scanning aroundday 30 of the last breeding before starting thetreatment. The points to ponder in planning to abort abitch include its pregnancy confirmation and the60safety, reliability and the ease of administration ofthe drug used.The first stage of pregnancy begins atfertilization and ends a few days after implantation.During this time pregnancy cannot be confirmed andinduction of abortion is difficult because of therefractory nature of corpus luteum to exogenousmedications. Termination of pregnancy at this stagecan be attempted with medications like estrogens,prostaglandins and anti progestins. During thesecond stage, pregnancy can be confirmed andabortion can be induced if necessary. Abortion can beinduced with prostaglandins, antiprolactin agents(dopamine agonists such as bromocriptine orcabergoline), combination of prostaglandins anddopamine agonists or with inhibitors of progesteronesecretions (epostane) or antiprogestins (mifepristoneor aglepristone). Third stage is one that begins withthe calcification of fetal structures and abortion isalways associated with expulsion of foetus. In thisstage abortion might induce premature parturitionwith delivery of live pups. Hence the best time forinitiation of abortion protocols in bitches is betweendays 30 and 35 from the date of last breedingINDUCTION OF ABORTION PRIOR TOIMPLANTATIONFertilization of eggs and the initial 6-10 daysof embryonic development take place in theoviducts. Large doses of estrogens can prolongretention time of embryo within the oviduct thatleads to the degeneration and death of embryo. Themechanism of action of oestrogen is in two ways,firstly it tightens uterotubal junction and thus