The relationship between ejaculation intervals and semen quality in 4 male cats aged 3-5 years was investigated in this study. Semen was collected 10 times at intervals of every day, every other day, and every three days using an artificial vagina. Semen was collected consecutively twice on the day of semen collection, and the semen quality was examined. In semen collected every day, the number of sperm in the first collection decreased, and the frequency of immature sperm rapidly increased after the 4th day. In semen collected every other day and every three days, although the semen volume markedly varied among the animals on both first and second collections, the volume remained stable for each animal, the number of sperm was similar in the first and second collections, but was clearly larger in the first collection (p<0.01). Sperm motility and abnormality were stable among the various intervals and between the first and second collections in each animal.

ABSTRACT. The spermatogenic function and plasma testosterone (T) level in the sex maturation process were investigated as to 180 mixed breed cats ranging from 4 months to 2 years in age to be castrated. Testis/epididymis weights reached a peak at 10 and 8 to 9 months of age, respectively. In the testis, sperm appeared at 5 months of age. At 7 months of age, sperm were observed in 96.2% of the cats. In the tail of the epididymis, sperm appeared in 46.9% of the cats at 6 months of age and in all cats at 8 or more months of age. Furthermore, the mean plasma T level rapidly increased at 8 months of age, and reached a peak (2.64 ± 0.68 (SE) ng/ml) at 10 months of age. Three of 180 cats (1.67%) had unilateral cryptorchidism. These results suggest that the spermatogenic function in male cats becomes mature at 8 to 10 months of age. KEY WORDS: male cat, sexual maturity, spermatogenesis, testosterone, testis.J. Vet. Med. Sci. 66(9): 1125-1127, 2004 Domestic cats are seasonally polyestrous animals. In female cats, puberty begins at an average age of 8 to 10 months [3,7]. Male cats are known to be non-seasonal breeders [10], but several studies have suggested the influence of seasons on the spermatogenesis [4,5].In mature male cats, some studies have investigated testis weight [4], testicular histology [2, 9, 11], plasma testosterone (T) levels [1 ,4, 5, 11, 13], testicular venous blood T levels [11], and epididymal sperm [9,12].No recent studies have further investigated the development of spermatogenesis and secretion of sex hormones in the sex maturation process in male cats. As studies on prepubertal male cats, Sanchez et al. histologically evaluated Leydig cells [9] and seminiferous tubules [8] in the sex maturation process, and Elcock and Schoning [2] histologically evaluated the testis and epididymis with respect to age, but they did not investigate spermatogenic function; Sanchez et al. [8] reported that spermatogenesis became mature at 8 months of age or older in a small number of cats.In this study, we investigated the development of spermatogenesis in the sex maturation process by using the testis and epididymis of male cats to be castrated. We also examined the changes in plasma T levels. MATERIALS AND METHODS Animals:We used 180 male mixed breed cats ranging from 4 months to 2 years in age to be castrated in an animal hospital (Kanagawa, Japan).Orchiectomy: Orchiectomy was performed under general anesthesia. For anesthesia, 0.05 mg/kg of medetomidine hydrochloride (Domitor ® , Meiji Seika Kaisha, Ltd., Tokyo, Japan) was intramuscularly administered, and 15 min later, 2 mg/kg of ketamine hydrochloride was intramuscularly administered. The entire testis and epididymis were extirpated. Measurement of testis/epididymis weights:In resected specimens, the testis was isolated from the epididymis. Left and right testis/epididymis weights were measured. Appearance of sperm in the testis and tail of epididymis:To investigate the appearance of sperm in the testis and tail of the epididymis in the sex maturation process, ...