Oestrus was induced using subcutaneous administration of 500 IU equine chorionic gonadotropin (eCG) and 1000 IU human chorionic gonadotropin (hCG) (eCG/hCG).
Five bitches were given 1000 IU hCG 11 days after eCG/hCG administration.
Examinations with ovarian ultrasonography using a 7.5â€MHz sector transducer, vaginal cytology, and assays of serum oestrogen and progesterone were performed daily until 20 days after eCG/hCG administration.
Serosanguineous vaginal discharges and vaginal cytology of two of the bitches were observed.
New follicular growth (>1.0 mm in diameter) was observed in all bitches from 2 to 8 days after eCG/hCG administration.
The mean diameter of follicles and maximum numbers of follicles per ovary ranged from 2.8 to 5.5 mm and 4 to 16, respectively.
The elevation in oestrogen concentrations after eCG/hCG administration was observed in all bitches, and elevation in progesterone concentration (>2 ng mL−1) was observed in three bitches.
However, no follicles ovulated until 9 days after hCG administration.
In conclusion, although the number of examined bitches were limited, follicular growth in ovaries clamped at a subcutaneous site can be monitored using ultrasound imaging.
Ovarian ultrasonography showed that eCG/hCG administration induced new follicular growth and hCG administration induced increases in oestrogen concentrations but not ovulation by hCG administration.
Source: Maki Hirata Fuminori Tanihara Masayasu Taniguchi Mitsuhiro Takagi Tsukasa Terazono Takeshige Otoi, Follicular development of canine ovaries stimulated by a combination treatment of eCG and hCG. VMS, Early View. First published: 01 October 2018 https://doi.org/10.1002/vms3.121
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