Reproduction in Domestic Animals

Reproductive Physiology, Pathology and AI in Cat 147this method (Chatdarong et al. 2007). Addition ofEquex STM (Nova Chemical Sales, Scituate Inc., MA,USA) paste to a Tris–egg yolk extender reduces acrosomedamage after freezing-thawing, but may have atoxic effect during incubation, leading to a fasterdecrease in sperm viability (Axnér et al. 2004). Washingfrozen-thawed spermatozoa by centrifugation to removethe freezing extender including the Equex STM pastehad, however, no beneficial effect on sperm longevity ina preliminary study (Axne´r et al. 2006). Addition ofantioxidants to the freezing buffer has been shown toimprove post-thaw cat epididymal sperm quality(Luvoni et al. 2002; Thuwanut et al., 2008).Ovulation induction and timing of inseminationIn the absence of the mating stimuli, ovulation must beartificially induced before AI can be carried out. Thelarge variation in the female oestrous cycle complicatesdetermination of the optimal time for ovulation induction.Ultrasound evaluation may be a reliable method tofollow follicular maturation (Malandain et al. 2002).The occurrence of spontaneous ovulation may contributeto difficulties in timing the AI (Lawler et al. 1993;Chatdarong et al. 2007). In order to control the oestrouscycle, studies on different hormonal therapies have beenperformed (Pelican et al. 2006). Pharmacological inductionof oestrus and ovulation cause, however, abnormalhormonal profiles that may interfere with fertility(Pelican et al. 2006). Ovulation induction is usuallycarried out with one or two injections of hCG inmidoestrus (Pelican et al. 2006; Tsutsui 2006; Chatdaronget al. 2007). For induction of oestrus, a combinationof eCG with an injection of hCG 80–84 h later isoften used (Pelican et al. 2006). Both hCG and eCGstimulate the production of antibodies, hence, frequentadministration can lead to decreased treatment success(Pelican et al. 2006). The optimal protocol for ovulationinduction and timing of ovulation induction remains tobe elucidated.Spermatozoa should be inseminated within 49 hafter ovulation induction as no fertilizations have beenobserved to occur after this time (Sojka et al. 1970;Howard et al. 1992). Feline spermatozoa probably donot require a long time for capacitation. Niwa et al.(1985) reported that 100% of homologous oocyteswere penetrated by epididymal spermatozoa within30 min after insemination, while ejaculated cat spermatozoaseem to need 2.5–3 h for in vitro capacitation(Long et al. 1996). Considering the reduced longevityof frozen-thawed spermatozoa, they should probablybe inseminated close to ovulation. The optimal timefor AI in relation to ovulation has, however, not beenfully elucidated although some studies report AI atdifferent times with some conflicting results concerningthe effect of pre-ovulatory anaesthesia on ovulation(Howard et al. 1992; Tsutsui 2006; Chatdarong et al.2007).Techniques of semen depositionPregnancies have been achieved with intravaginal as wellas with surgical or laparoscopic intrauterine or intratubalsemen deposition (Sojka et al. 1970; Platz et al.1978; Howard et al. 1992; Tsutsui 2006; Tsutsui et al.2001). In most species as well as in the cat, intrauterinesemen deposition yields better pregnancy results thanvaginal deposition although the cat spermatozoa aredeposited in the vagina during natural coitus (Linde-Forsberg et al. 1999; Tanaka et al. 2000; Thomassenet al. 2006; Tsutsui 2006; Chatdarong et al. 2007).Surgical insemination is an invasive procedure that isnot allowed in all countries. Therefore, studies ontranscervical AI have been performed. Transcervicalcatheterization in the cat is, however, associated withdifficulties because of the vaginal anatomy. Abdominalfixation of the cervix as carried out with the Norwegiantranscervical catheter for the bitch is not possible in thequeen because of the position of the cervix and thenarrow cranial vagina makes endoscopy-guided transcervicalpassage impossible (Linde-Forsberg et al. 1999;Chatdarong et al. 2002; Zambelli et al. 2004; Thomassenet al. 2006). Zambelli and Castagnetti (2001)performed rectally guided transcervical catheterizationusing a rounded tip needle inserted at the cut end of a 3-Fr tomcat catheter.Birth of live kittens has resulted after transcervicalintrauterine deposition of frozen-thawed semen with thehelp of a catheter modified from a transcervical catheterfirst described by Swanson and Godke (1994) (Chatdaronget al. 2005, 2007). The result with birth of livekittens is promising for the use of non-surgical AI insmall felids, although the protocol still needs to berefined to improve pregnancy results and to allow theuse of a lower sperm number (Chatdarong et al. 2007).In conclusion, although more studies on evaluation offollicular maturation, protocols for artificial ovulationinduction, semen conservation and techniques of AI areneeded before an optimal protocol for routine AI in thecat can be developed, some promising progress has beenachieved in the development of semen conservation andAI in the cat.ReferencesAxne´r E, Linde Forsberg C, 2007: Sperm morphology in thedomestic cat, and its relation with fertility: a retrospectivestudy. Reprod Domest Anim 42, 282–291.Axne´r E, Stro¨m B, Linde-Forsberg C, Gustavsson I, LindbladK, Wallgren M, 1996: Reproductive disorders in 10 domesticmale cats. J Small Anim Pract 37, 394–401.Axne´r E, Stro¨m Holst B, Linde Forsberg C, 1998: Morphologyof spermatozoa in the cauda epididymidis beforeand after electroejaculation and a comparison with ejaculatedspermatozoa in the domestic cat. Theriogenology50, 973–979.Axne´r E, Hermansson U, Linde-Forsberg C, 2004: The effectof Equex STM paste and sperm morphology on post-thawsurvival of cat epididymal spermatozoa. Anim Reprod Sci84, 179–191.Axne´r E, Kronsell A, Linde-Forsberg C, 2006: Effect of postthawcentrifugation on viability of epididymal cat spermatozoa.in: Luvoni GC, Thuro´czy J (eds), Proc. 5th BiannualEVSSAR Conf. Budapest, April, P06.Axne´r E,A˚ gren E, Ba˚ verud V, Stro¨m Holst B. Infertility in thecycling queen: seven cases. Journal of feline medicine andsurgery, 2008: DOI: 10.1016/j.jfms.2008.04.005.Ó 2008 The Author. Journal compilation Ó 2008 Blackwell Verlag