Prediction of the oocyte recovery rate in the bitch

In order to investigate the possibility of predicting the recovery rate of oocytes for use in a sperm-zona pellucida binding assay, ovaries were obtained from 67 bitches of 37 different breeds, and cumulus-oocyte complexes (COCs) were recovered by mincing the ovaries with a scalpel. The mean number of COCs recovered was 37.2 +/- 34.1 (range 0-145) per ovary. Age significantly affected COC recovery rates. From bitches 1-6 years old, 54.2 +/- 35.1 COCs/ovary were recovered, compared to 26.4 +/- 29.0 from bitches 7-13 years old (P = 0.003). The morphology of the uterus or the presence or absence of ovarian structures had no significant effect on COC recovery rates, although there was a tendency for more COCs to be recovered from ovaries with only follicles visible on the surface. There were no significant correlations between body weight or ovarian weight and COC recovery rates. There was a high correlation in the COC recovery rate between the two ovaries of a bitch, enabling an approximate estimation of the COC recovery rate from the second ovary when the COCs from the first ovary have been recovered. The large variation in COC recovery rates between bitches stresses the need for storage of canine oocytes in order to secure a high enough number of oocytes for a homologous sperm-zona pellucida binding assay in the dog.