termination of pregnancy in bitches - Jivaonline.net

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GENERAL ARTICLE4. COMBINATION OF PROSTAGLANDINAND DOPAMINE AGONISTSimultaneous administration of prostaglandinand dopamine agonist is found to be highly effective.Therapy begins 28 days after first breeding.Cloprostenol is administered subcutaneously onalternative days at a dose rate of 1 µg/kg and the drughas to be administered three times. Oral cabergolinehas to be given at a dose rate of 5µg/kg body weightfor 9 days. This regimen reduces the adverse effectsof prostaglandin therapy alone and increases theefficacy of prolactin antagonists. When the bitcheswere treated for approximately 9 days, 100 percentshowed resorption and there was generally no sideeffects except sanguinous vaginal discharge (Onclinet.al, 1995).5. ANTI PROGESTERONE THERAPYAnti-progestins are synthetic steroids thatbind with great affinity to progesterone receptors,preventing progesterone from exerting its biologicaleffects. After administration of the drug peripheralprogesterone concentration remains unaltered but itsaction is blocked. In dogs, the anti-progestinsmifepristone and aglepristone have been used forexperimental and clinical purposes, includingpregnancy termination and management ofpyometra.a. Mifepristone: -Mifepristone is a progesterone andglucocorticoid antagonist. It is more potent as ananti-progestin than as an anti-corticoid. In pregnantwomen, mifepristone is able to interrupt earlypregnancy in 80 percent of cases without any majorside effects. To improve its efficacy, mifepristone iscurrently used in combination with low doses ofprostaglandin analogs such as misoprostol. Theefficacy of combined treatment (mifepristone plusmisoprostol) is 96 percent in humans. The drug act asa progesterone receptor antagonist at the level of theuterus independent of any additional effects on lutealfunction. Premature cessation of luteal function mayhave occurred secondary to the termination ofpregnancy or may represent a luteolytic effect oftreatment independent of pregnancy status.Mifepristone has been demonstrated to induce directluteolysis and has an anticorticoid activity.This drug is orally active and has beenshown to be safe and effective in terminatingpregnancy after 30 days of gestation. The treatmentprotocol involved oral administration of drug at therate of 2.5 mg/kg twice daily for 4-5 days or untilabortion or resorption occurred (Concanoon et.al,1990). It is a competitive antagonist of progesteroneon the receptor level thus having most clinical effectsin the presence of progesterone. Preparation Tab.MTPILL 200mg, MEFIPIL 200mg, UNWANTED200mgB. Aglepristone: - This is a relatively newantiprogesterone drug developed for animal use.Aglepristone can be used any time up to day 45 forsafe effective termination of pregnancy (Fieni et. al,2001). Aglepristone does not modify plasmaconcentrations of progesterone, prostaglandins,oxytocin or cortisol within 24 hours after itsadministration but induces an increase inconcentrations of prolactin within 12 hours in bitchestreated in mid pregnancy (Galac, et. al, 2000). Thiscan explain the mammary gland congestion typicallyobserved after mid pregnancy termination.Shortening of the inter-oestrous interval andprolactin release seems to prove a direct or indirectaction of aglepristone on hypothalamic-pituitaryaxis. As an abortifacient, aglepristone acts like aprogesterone antagonist, at the uterus level and doesnot have direct and immediate luteolysis properties.Termination of pregnancy occurs in the presence ofhigh plasma progesterone concentrations (Baanet.al, 2005)..The early administration of aglepristone at 0to 25 days after mating always resulted in preventionof pregnancy. The later administration ofaglepristone at day 26 to 45 after mating inducedresorbtion or abortion within seven days in 96percent of cases. There were no untoward sideeffects. The drug can be administered at a dosage ofJIVA Vol. 10 Issue 1 April 201263
GENERAL ARTICLEJ. Ind. Vet. Assoc., Kerala. 10 (1)10mg/kg body weight (0.33ml/kg/day)subcutaneously twice at 24 hour interval. Efficacy oftreatment for termination of pregnancy is reported tobe 95 percent. No side effects were observed exceptmammary development and lactation. PreparationALIZIN 10 ml vial 30 mg/ml.6. OGESTERONE SYNTHESIS INHIBITORSProgesterone production can be blocked bythe hydroxyl steroid dehydrogenase isomeraseenzyme inhibitors, which prevent the conversion ofprognenelone to progesterone. Prognenelone isbiologically inactive, and therefore progesteronesupport for the pregnancy is lost, resulting inresorption or abortion (Simpson, 1998). Epostane isone such enzyme inhibitor that has no intrinsicoestrogenic, androgenic or progestogenic activity.When administered subcutaneously at the onset ofmetoestrus (dioestrus), epostane will prevent orterminate pregnancy. It can be given at a dose rate of5mg/kg body weight orally for 7 days (Keister et. al,1989).7. TAMOXIFEN CITRATEIt acts as an antiestrogen in premenopausalwomen but has estrogenic activity in dogs. It mayinterfere with zygote transport and/or implantation.Relatively high doses of drug are given twice dailyduring proestrus, oestrus, and early metoestrus. Thedrug was effective in preventing or terminatingpregnancy if administration began during proestrusor estrus or on day 2 of estrus. Efficacy was muchpoor in if the treatment commenced on day 15onwards. It can be given at a dose rate of 1mg/kgorally twice a day for 10 days. A high incidence ofpathological changes in the bitch's reproductive tractis induced by tamoxifen, including ovarian cysts andendometritis, and the compound is of little value forpotential breeding animals (Bowen et.al, 1988).Preparation TAMOFEN Tab 10 mg, TAMOXIFENTab 10, 20 and 40 mg.8. EMBRYOTOXIC AGENTSSeveral novel embryotoxic agents such asphenyltriazole isoindole and isoquinolinecompounds have been evaluated in the bitch. Theyare most effective when given around the time ofimplantation and often only a single administration isrequired. A single sub cutaneous or intra muscularinjection of 2-(3-ethoxy-phenyl)-5, 6-dihydro-striazole[5,1-a]isoquinoline(DL 204-IT) dissolved orsuspended in an oily vehicle is sufficient. Theoptimal time of treatment was found to be day 20 ofgestation, at which time the smallest effective dosewas 6.25 ng/kg (Galliani et. al, 1982). Howevermany of these agents have toxic side effectsincluding vomiting, diarrhoea, weight loss, pyrexia,lethargy and immunosuppression.9. DEXAMETHAZONEDexamethasone administered beginning atmid-gestation can terminate pregnancy in dogs,presumably by activating endogenous mechanismssimilar to those involved in parturition. It can resultin the production of oestrogen and prostaglandin bythe fetoplacental unit. Single dose of glucocorticoidsare not efficacious in the bitch. It can be given at adose rate of 200µg/kg body weight for 7 days andthen at a tapering dose of 10-20 µg/kg for next 3 days(Wanke et. al, 2002). Advantages of such a therapyfor pregnancy termination include the fact that itinvolves only oral administration of a relativelyinexpensive drug; however repeated administrationand high doses make the method impractical.Preparation: - DEXONA Tab 0.5mg, WYMESONETab 0.5 mgCONCLUSIONBefore deciding treatment for misalliance,vaginal cytology should be performed to make surethat mating had taken place. Aglepristone,oestrogens and tamoxifen citrate are the drugs whichcan be preferred for the treatment of misalliance in64
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