183 ULTRASONOGRAPHIC MONITORING OF CANINE OVARIES CLAMPED AT SUBCUTANEOUS SITE AFTER FOLLICLE-STIMULATING HORMONE TREATMENT

Follicle-stimulating hormone (FSH) alone can induce oestrus in bitches, but few reports describe oestrous induction by FSH because pregnant mare serum gonadotrophin (PMSG) has been more successful than FSH for oestrus induction. Real-time ultrasonography can show canine ovarian follicle development, but no method can determine or predict ovulation accurately. Moreover, the ovary location and size complicate imaging. Using ultrasonography, we investigated FSH treatment stimulation of canine ovary follicles, with clamping of the ovaries at a subcutaneous site. Bilateral malacotomy of four 5-year-old Beagle bitches (mean weight 10.3 ± 2.0 kg) with normal oestrous cycles was done using a ventral flank abdominal approach with routine techniques and materials. Each ovary that maintained blood circulation from the suspensory ligament was clamped at a subcutaneous site through muscles of the abdomen. After about six months of bilateral malacotomy, four bitches at the anestrous (two bitches) and diestrous (two bitches) stages of the oestrous cycle were given 0.5 Armour units of FSH twice daily for 5 days. Examinations with ovarian ultrasonography with 7.5 MHz sector transducer, vaginal cytology, and serum concentrations of progesterone and oestradiol were performed daily from the day before the start of FSH treatment through 7 days after FSH treatment. After 15 days of ovarian examination, each bitch received the same FSH treatment twice continually at 15-day intervals. No serosanguineous vaginal discharge was observed during the ovarian examination. The concentrations of progesterone (<0.045–9.6 ng mL–1) and oestradiol (<9.7–81.4 pg mL–1) varied through all treatments. Comparison of the concentrations of progesterone (<0.045–7.6 ng mL–1) and oestradiol (<9.7–30.3 pg mL–1) at the start of FSH administration in each trial revealed that elevated concentrations of both progesterone and oestradiol were observed in the first treatment in 3 bitches. Regarding the second and third treatments, no elevation of concentration was found for progesterone or oestradiol. A new follicular growth was observed in 1 animal after the third FSH treatment, but no follicular growth was found for the other animals. No correlation was found between follicular development and the profile of either progesterone or oestradiol. Ultrasonography proved that FSH stimulation alone cannot induce follicular growth by a single treatment, but it might increase the levels of progesterone and oestradiol, which are not correlated with follicular development and oestrous cycles at the start of FSH treatment.