Reproduction in Domestic Animals

Reproductive Physiology, Pathology and AI in Cat 145subsequently redistributed to the isthmus (Chatdaronget al. 2004), and the oocytes are fertilized in the oviductaround the time of ovulation (Swanson et al. 1994). As asingle mating or AI at the time of ovulation inductionmay result in conception, the fertile life of cat spermatozoamust be at least the same as the time betweenmating and ovulation (Chatdarong et al. 2007).Adrenal progesterone secretionProgesterone is produced by the corpora lutea afterovulation but can also be released from the adrenalglands after stress or injection with ACTH (Chatdaronget al. 2006b). A serum progesterone concentration of16.3 nmol ⁄ l has been observed after ACTH injection ofan ovariohysterectomized female, indicating that thefeline adrenals may produce substantial amounts ofprogesterone (Chatdarong et al. 2006b). ACTH administrationto sows has been shown to cause an alteredprogesterone profile, a possible decrease in the time fortransport of oocytes ⁄ embryos through the oviduct andloss of embryos (Brandt et al. 2007). Therefore, onecannot exclude that stress may have negative effects alsoon early pregnancy in cats, a phenomenon that warrantsfurther research in this species.Disorders of the Female Genital OrgansInfertility in the cycling queenInfertility in the queen with normal ovarian activitypresents a diagnostic challenge for the clinician. In thequeen with normal cycles, normal mating and matinginducedovulation, CEH or low-grade endometritis maycause infertility without any other obvious clinical signs.CEH is believed to be the result of cumulative changesin the endometrium induced by oestradiol and progesterone(Perez et al. 1999; Misirlioglu et al. 2006). Noefficient treatment for CEH except ovariohysterectomyhas been reported. CEH can be diagnosed with ultrasoundor hysterography (Chatdarong et al. 2005). Lowgradeendometritis is extremely difficult to diagnose.Uterine biopsy is an invasive procedure and does notguarantee that the whole endometrium is accessed andmay therefore give a false negative result if the pathologicalchanges are focal. Vaginal discharge is anindication of genital pathology, but may not be presentif the cervix is closed, the infection is mild, or in thepresence of a chronic inflammation. Leukocytes in avaginal swab indicate an acute inflammation, butleukocytes may be few or absent even if the queen hasa uterine infection. Vaginal bacterial culture is notdiagnostic because the normal vaginal bacterial floracannot be distinguished from that of the flora associatedwith uterine pathologies, such as endometritis (Stro¨mHolst et al. 2003). If an endometritis is suspected,bacterial culture can, however, be used to select anappropriate antibiotic. The likelihood of taking asample from the vagina that is truly representative ofthe uterine flora (i.e. finding the same bacteria in avaginal swab as those that are present in the uterus), isprobably higher during oestrus when the cervix is open,than at other stages of the cycle, although this has neverbeen confirmed. To decrease the risk of selectingbacterial strains resistant to antibiotics, the decision toput an infertile queen on antibiotics should only bemade after a thorough clinical examination to rule outother causes of infertility. Mild degenerative changes ofthe endometrium may be difficult to detect on ultrasoundbut can be a reason for treatment failure (Axne´ret al., 2008).Reproductive Physiology of the Male CatIn tomcats, spermatogenesis is established at 6–8 months of age, at which time an increase in testicularweight and testosterone production can be observed.The spermatogenic function in young toms is usuallynot comparable to that of mature males until after8 months of age (Tsutsui et al. 2004b; Siemieniuch andWoclawek-Potocka 2007). The daily sperm productionhas been estimated to be 16 · 10 6 spermatozoa ⁄ testis(Franc¸a and Godinho 2003). The effect of season onreproductive function in the male domestic cat isinsufficiently explored and reports are contradictory(Johnstone et al. 1984; Spindler and Wildt 1999). In aretrospective study on sperm morphology in privatelyowned cats, we found that the percentage of normalspermatozoa was higher in ejaculates collected from catsduring the breeding season than during the non-breedingseason, indicating a possible effect of season on malefertility in cats (Axnér and Linde Forsberg 2007).Blottner and Jewgenow (2007) found seasonal variationsin epididymal sperm quality and testosterone productionbetween spring and autumn. These recent findingsindicate that there might be seasonal variation also indomestic cat male fertility.Semen qualitySemen quality displays large individual variations in thecat. In a retrospective study, the median percentage ofmorphologically normal spermatozoa in an unselectedpopulation of cats was 44% (n = 48), (Axnér and LindeForsberg 2007). Of all cats with