The aim of the study was to evaluate the efficacy of a 4.7 mg deslorelin implant in tom cats. Nine mature male cats were included in the deslorelin group and five cats in the control group. Before the study started, all cats were confirmed to have distinct sexually dimorphic behaviour. Blood samples were taken on the implantation day, at day 7 and at day 15, then monthly, in order to measure serum dihydrotestosterone (DHT) and 17beta(β)-oestradiol concentrations. The deslorelin group (n = 9) was divided into two subgroups: five cats (cats 1–5) were neutered in the postimplantation period during suppression of sexually dimorphic behaviour, and four cats (cats 6–9) were neutered after re-expression of sexually dimorphic behaviour. The control group cats (n = 5) were castrated without administration of the implant. Sexually dimorphic behaviours ceased within a mean ± SD of 13–58 days (23.30 ± 14.17) after implantation. DHT concentration decreased within 30 days. The mean duration of suppression was 26.5 ± 7.42 months and reactivation coincided with increased DHT values reaching preimplantation concentrations within 1 month. 17β-oestradiol concentrations significantly correlated with DHT concentrations (P <0.01). For cats castrated during suppression of sexual behaviour, the length of the long axes of the nuclei of Leydig cells, the diameter of seminiferous tubules and the height of the epithelium of the seminiferous tubules did not change until 3–6 months after implantation, whereas at 12 and 32 months the measured values were even lower than in the control group. For cats castrasted after reactivation, the length of long axes of the nuclei of Leydig cells and the diameter of seminiferous tubules approached the values of the control group between 4 and 6 months after reactivation. A deslorelin implant (4.7 mg) suppresses sexually dimorphic behaviour in tom cats without any side effects and with full reversibility; however, duration of suppression is highly individual.

To evaluate the expression of AMH and its receptor AMHRII, ovaries of 33 p cats were investigated by western blot and immunohistochemistry. After ovariohysterectomy, the cats were grouped according to pregnancy stages and ovarian/placental endocrine activity: group I (n = 3, 24–29 days), II (n = 8, 32–40 days), III (n = 4, 41–46 days), IV (n = 6, 53–61 days) and according to cycle stages: V (n = 6, interestrus) and VI (n = 6, estrus). Serum progesterone- and AMH-concentration was measured. Follicle numbers did not differ between groups. The number of corpora lutea was higher in pregnant cats than in the non-pregnant cats. Serum AMH concentration was at maximum between day 30 and 50 of gestation, and was higher than in non-pregnant cats, then decreased towards term (p < 0.05). In the ovaries, AMH immunopositivity was observed in granulosa cells of secondary and antral follicles, and in interstitial cells of corpora lutea; highest percentage of immunopositive areas was detected in group III (p < 0.05). A positive correlation between the number of corpora lutea and the positive AMH signals in ovarian tissue was determined (r² = 0.832, p < 0.05); however, only during mid-gestation (group II). Expression of AMHRII was in close co-localization with AMH and strong in the interstitial cells surrounding follicles undergoing atresia. AMHRII expression did not differ between pregnant groups but was higher compared to estrus cats (p ˂ 0.05). We conclude that AMH and AMHRII expression in the feline ovary is comparable to other species. The high serum AMH concentration and ovarian AMHRII expression between day 30 and 50 of gestation are probably related to ovarian activity and follicular atresia.

The purpose of this study was to compare the expression of 3β-hydroxystreroid dehydrogenase (3β-HSD) in the uterus and ovary of healthy dogs and those with cystic endometrial hyperplasia and/or pyometra complex (CEH-pyometra). Eighteen female dogs were included in the study. Eleven bitches with open cervix CEH-pyometra were included in the CEH-pyometra group and seven diestrus bitches in the control group. For immunostaining a rabbit polyclonal, one raised against recombinant human type 2 (adrenal/gonadal) 3β-HSD was used. Progesterone (P4) concentrations were not statistically different between the groups. Strongly stained large interstitial cell groups in the ovarian medulla were observed particularly in CEH-pyometra group although these cells in the control group were weakly or moderately stained and existed singly or paired. The expressions of 3β-HSD in luminal epithelium (42.40 ± 22.40% vs. 18.42 ± 13.15%, P < 0.05) and glandular epithelium (32.80 ± 27.05% vs. 2.94 ± 7.79%, P < 0.01) of endometrium were significantly higher in CEH-pyometra group than those in the control group. The expression of 3β-HSD in CL was higher (29.38 ± 9.58% vs. 22.94 ± 4.97%) in CEH-pyometra group than that of control group although the differences were not significant (P > 0.05). Similarly, the significant increase in the expression of 3β-HSD in ovarian interstitial cells (33.86 ± 29.44 vs. 1.13 ± 2.97, P < 0.05) was found in CEH-pyometra group compared to the control group. The study revealed that 3β-HSD expression in the endometrium of canine CEH-pyometra was significantly high.