Monitoring follicular dynamics to determine estrus type and timing of ovulation induction in captive brown bears (Ursus arctos).

It is important to understand ovarian physiology when developing an artificial insemination (AI) protocol. Brown bears (Ursus arctos) have a breeding season from May to July, although the type of estrus (polyestrus or monoestrus) is still contested. The present study aimed to define the ovarian dynamics, including follicular waves and ovulatory follicle size, and estrus type in brown bears. Six brown bears were used for ovarian ultrasonography; four were observed between April and October (before the start and after the end of the breeding season) and two in June (breeding season). In addition, we attempted to induce ovulation by administering a gonadotropin releasing hormone (GnRH) agonist. We observed follicular development in April in four bears, but follicles did not develop to greater than 6.0 mm in diameter until May. Thereafter, a group of follicles developed to more than 6.0 mm and grew as dominant follicles, except in one bear. After ovulation and subsequent corpus luteum (CL) formation, the follicular waves disappeared. Furthermore, in three bears treated with GnRH, follicles between 8.2 to 11.2 mm in diameter at the time of treatment ovulated and formed CLs. In two bears, follicles between 5.8 to 8.8 mm ovulated spontaneously within the observation interval. Our results suggest that brown bears may be monoestrous animals. Therefore, AI can only be performed once during the breeding season. Our results also suggest that dominant follicles larger than 8.0 mm are a suitable size for inducing ovulation.

Monitoring follicular dynamics using ultrasonography in captive brown bears (Ursus arctos) during the breeding season.

Artificial insemination (AI) may be a useful tool in the reproductive management of endangered animals, including bears. To establish an AI program for bears, we investigated follicular dynamics using weekly transrectal ultrasonography in six captive brown bears. Along with ultrasonography, we monitored plasma progesterone (P4) and estradiol-17ß (E2) concentrations. Furthermore, two bears were administered a gonadotropin releasing hormone (GnRH) agonist to induce ovulation on the first day on which the largest follicle reached more than 10.0 mm in diameter. Brown bears showed two patterns of follicular development in the early and late periods of the breeding season. In the early period (May to mid-June), multiple follicular waves were observed; namely, many follicles developed, and the largest follicles grew to less than 6.0 mm in diameter then regressed. In the late period (mid-June to July), one or two follicles grew to greater than 6.0 mm in diameter and developed as dominant follicles. Moreover, the growth rate of the largest follicle in the late period was faster than that in the early period of the breeding season. One bear with a follicle of 13.1 mm ovulated spontaneously, and one bear ovulated when the follicle was 10.2 mm in diameter after GnRH agonist treatment. Plasma E2 concentrations increased and showed peaks five to seven days before the largest follicles reached their maximum size. Plasma P4 concentrations increased on the day the corpus luteum could be detected using ultrasonography. This is the first study that showed there are two patterns of follicular development in brown bears. Furthermore, the largest follicle reaching greater than 10.0 mm in diameter could be an indicator of the appearance of ovulatory follicles.

Eosinophilic plasmacytic conjunctivitis concurrent with gingival fistula caused by Schizophyllum commune in a captive cheetah (Acinonyx jubatus).

We describe for the first time the diagnosis of Schizophyllum commune infection in a captive cheetah. Eosinophilic plasmacytic conjunctivitis was detected histopathologically in a biopsy specimen. Both a second surgical specimen and drainage fluid from a gingival mass and fistula contained fungal hyphae in giant cells with granulomatous inflammation. Allergic S. commune mycosis was suspected at this point. A monokaryotic isolate was characterized morphologically, and then identified genetically. Treatment with itraconazole and pimaricin was effective.