Clinical, Ovulatory and Histological Effect of a Postnatal Testosterone Treatment in Female Dogs.

It has been described in some female mammalian species that postnatal androgenization causes reproductive structural and functional abnormalities. The objective of this study was to describe the clinical, ovulatory and genital effects of postnatal androgens in female dogs. Ten newborn female crossbred puppies were randomly assigned to: testosterone enanthate 18 mg/100 g sc (TE; n = 5) or placebo sc (PL; n = 5). The puppies were physically followed up until puberty when ovulation was tested by serum progesterone. Then, ovariohysterectomies were performed, and genital tracts were grossly and histomorphometrically examined. At puberty, all the females had normal estrous behavior and ovulated without age and body weight differences. All TE puppies presented mild clitoris enlargement. Gross and microscopical ovarian examination did not reveal differences. Conversely, the endometrial area occupied by uterine glands as well as the height of the glandular and luminal epithelium were higher in the TE than in the PL group (<0.01). The height of the endometrium and myometrial thickness did not differ between groups. It was concluded that a supraphysiological postnatal dose of testosterone did not affect ovulatory capacity, nor did it provoke gonadal histological alterations, although it caused an increased area of endometrial glands and a higher uterine epithelium.

Effect of a GnRH Antagonist on Anti-Müllerian Hormone and Follicular Population in Anestrous Bitches.

The objective of this study was to describe the effect of the third-generation GnRH antagonist, acyline, on ovarian follicular population and serum anti-Müllerian hormone (AMH) concentrations in female dogs. Four late anestrous bitches were administered 330 µg/kg SC acyline every 10 days for 60 days and followed up for 45 days. Blood samples were drawn on days -1, 15, 30, 45, 60, 75, 90 and 105 for AMH determination. Then, the females were ovariectomized and the excised ovaries were gross and histologically evaluated. The total ovarian follicles were counted. None of the female dogs presented estrus during treatment. Only one bitch presented an ovulatory estrus 20 days after treatment. The total number of ovarian follicles in these bitches was 96,200.10 ± 26,125.12, with 84.13%, 11.36%, 7.8% and 0.01% corresponding to primordial, primary, secondary and antral structures, respectively. Pretreatment AMH concentrations were 0.62 ± 0.17 ng/mL. This hormone varied throughout the study period (p < 0.01), diminishing to nadir values during treatment to then rapidly recover after its effect (0.2 ± 0.05 vs. 0.67 ± 0.22 ng/mL; p < 0.01). Acyline rapidly and reversibly prevented the initiation of cycling without affecting follicle count but diminishing serum AMH concentrations.

Evaluation of Long-Term Effects of the Gonadotrophin-Releasing-Hormone Antagonist Acyline on Domestic-Cat Growth.

Acyline contraception has been described in cats, but few data are available on the drug's long-term effect on growth. The relevant data cover until puberty with no radiographic description. We investigated the radiographic parameters throughout bone growth in order to more completely determine the drug's safety. Thirteen male and 12 female cats were studied, with the kittens being randomly assigned to one of the following groups within the first 24 hours of birth: ACY, subcutaneous acyline, 33 µg/100 g, which injection was repeated weekly until age 3 months; or CO, untreated control. Body measurements were recorded weekly and radiographic parameters obtained from monthly radiographs of the antebrachium. In the ACY and CO male and female kittens, the body weight, withers height, and body length plus the age at the end of body growth and radial growth remained similar throughout the study (P> .05). Both female groups finished radial growth before the males (P< .05). The ACY females evidenced a longer radial length between the eighth and 28th weeks (P< .05). All groups closed their proximal and distal physes within the normal ranges described for the species. The bone-cortex width was lower in the ACY vs. the CO animals at weeks 52 and 60 in the males and at weeks 24, 48, 52, and 56 in the females (P< .05) The transient greater radial length and lower bone-cortex thickness observed in the treated cats were compensated for at the end of growth with no adverse clinical effects being observed. In conclusion, acyline as a contraceptive did not evidence a permanent or severe effect on domestic-cat growth.

Fecal Progestins Differentiate Pregnant From Nonpregnant Early Luteal Bitches.

Considering the high perimplantation progesterone (P4) secretion that occurs in female domestic dogs, we hypothesize that fecal P4 concentrations distinguishes pregnant from nonpregnant early luteal bitches. The objective of this study was to compare fecal P4 metabolites in early pregnant vs. nonpregnant early luteal bitches. Eighteen 2-6 years of age, 5-15 kg, pure-bred bitches, that were followed up for breeding management, and 2 ovariectomized (OVX) bitches were included in this study. On pregnancy day 18-28, a single fecal sample was collected from each animal. Fecal samples were frozen at -20°C until analysis. Pregnancy diagnosis was carried out by ultrasonography on day 21. Fecal samples were also collected from the 2 OVX bitches. Fecal P4 metabolites were extracted as based on methods described by Brown et al. (2008) and, then, measured by an electrochemiluminescence immunoassay. Eleven bitches were pregnant (PREG) while 7 were non-pregnant (N-PR). Fecal P4 metabolites concentrations were 283.9 ± 60.4 and 102.7 ± 19.1 (ng/g; P < .05) for PREG and N-PR, respectively. Both values were higher than those of the OVX bitches (9.9±1.1; P < .05). This noninvasive technique to measure P4 metabolites in feces appears as a simple and noncostly alternative for early pregnancy diagnosis in the domestic dog. Further large scale studies are necessary before this test could be widely recommended.

Development and proliferation of feline endometrial glands from fetal life to ovarian cyclicity.

In this study it was determined the progression of uterine gland development from late gestation to puberty in domestic felids. Cell proliferation patterns for luminal (LE), glandular epithelium (GE) as well as stroma (S) were also described. Twenty-four uteri from female kittens: 45 and 65 days of gestation and 1 to 5, 8, 12, 16, 20 and 24 weeks postnatally were obtained. Uterine cross-sections were submitted for routine histological and immunohistochemical quantification of proliferating cell nuclear antigen (PCNA) techniques. Although prenatal uteri presented no indication of adenogenesis, 1 week old uteri revealed an incipient budding of the LE. During the second week budding increased and a mild degree of tubulogenesis of the GE into the stroma was detected. From the third to fifth weeks coiling, branching and cross-sections of glands appeared. These latter findings were more evident in week 8 when GE began to penetrate through much of the S to week 24. PCNA immunostaining revealed that DNA synthesis decreased throughout the study in the 3 cell compartments; (P < 0.01). Luminal proliferation began prenatally, it maintained up to postnatal week 8 to markedly decrease to puberty (P < 0.01). From postnatal week 3 up to week 8, GE mitotic activity was elevated becoming low thereafter (P < 0.01). Stroma actively proliferated prenatally (P < 0.01), diminishing up to week 8 (P < 0.01) and again during the last weeks (P < 0.01) of the study. It was concluded that, in domestic felids, proliferation of LE begins prenatally, histological uterine adenogenesis commenced during the first postnatal week and both events concluded by postnatal weeks 5-8.

Postnatal exposure to a progestin does not prevent uterine adenogenesis in domestic dogs.

To assess the effects of a single supraphysiological postnatal administration of a progestogen on uterine glands in dogs, 10 females were randomly assigned to a medroxyprogesterone acetate 35 mg (MPA; n = 6) or placebo (n = 4) group within the first 24 h of birth. The safety of the treatment was also evaluated. A transient mild clitoris enlargement appeared in MPA-treated females. Microscopic postpubertal uterine assessment revealed the presence of uterine glands in all cases without significant differences in the area occupied by the glands per µm(2) of endometrium nor in the height of the uterine epithelium.