Successful pregnancy following gonadotrophin-releasing hormone analogue treatment in a previously infertile bitch.

A Labrador retriever bitch was presented with repeated unsuccessful breeding during both the third and fourth oestruses, even though accurate timing for natural mating was planned based on the results obtained using a semiquantitative luteinising hormone kit and a quantitative assay of progesterone. To identify the problem, serum luteinising hormone, follicle-stimulating hormone, progesterone, and oestradiol-17beta concentrations around the fourth oestrus stage were assayed by radioimmunoassay. Abnormal luteinising hormone fluctuations were detected during pro-oestrus and oestrus, and lower than normal progesterone concentrations were found during the mating period. In the fifth to seventh oestrus, the bitch was successfully treated with gonadotrophin-releasing hormone analogue at times based on the findings of the hormonal assays.

Induction of canine pyometra by inoculation of Escherichia coli into the uterus and its relationship to reproductive features.

To characterize oestrus-related factors affecting the induction of and recovery from pyometra in bitches, 60 clinically healthy beagle bitches were used for induction of pyometra by inoculation of Escherichia coli into the uterus during oestrous and metoestrous stages. The animals were classified into the following six groups according to inoculation time: Days 1-10, 11-20, 21-30, 31-40, 41-50 and 51-60 after LH surge. The incidence of pyometra during the periods Days 11-20 and 21-30 after LH surge was 90.9% and 78.9% respectively, while that during Days 1-10 and 51-60 after LH surge was less than 20%, and the patterns of the incidence of pyometra and the serum progesterone levels were similar. There was no difference in the incidence of pyometra induced in bitches less than 5 years old compared to bitches over 6 years old. Oestrus in all of the bitches with pyometra induced by E. coli returned with or without PGF 2alpha treatment, unlike in bitches with spontaneous pyometra. The duration of the oestrous cycle in the non-treated and PGF 2alpha-treated groups was 231.4+/-55.2 days and 162.1+/-40.6 days (P < 0.001), respectively, and there was no difference in the rate of return of oestrus between the two groups. The conception rate in all of the bitches in which oestrus had returned was 81.8%. The above findings indicate that the period during which severe pyometra could be induced was limited to the early stage in metoestrus.

Three-dimensional reconstruction of the equine ovary.

The equine ovary has a very unique structure in terms of its extreme large size, the presence of the ovulation fossa and the inverted location of its cortex and medulla. In the previous study, it was recognized that the application of three-dimensional internal structure microscopy (3D-ISM) to observe the mare ovary is very effective. Three-dimensional reconstruction of serially sliced images made by 3D-ISM was successful in this study with the aid of the sophisticated image processing technique. The rotation of the reconstructed ovary has been carried out with and without the application of the transparency technique in the ovarian stromal region. The spatial localization of follicles and corpus luteum was clearly visualized by rotating the reconstructed image of the ovary. The extraction of the images of follicles and corpus luteum was also available and gave a quantifiable understanding of their structure.

Immunohistochemical localization of steroidogenic enzymes in the corpus luteum and the placenta of the ribbon seal (Phoca fasciata) and steller sea lion (Eumetopias jubatus).

To study the luteal and placental function of pinnipeds, we analyzed the localization of steroidogenic enzymes (P450scc, 3 beta HSD and P450arom) in the corpus luteum and the placenta of ribbon seals (Phoca fasciata) and Steller sea lions (Eumetopias jubatus) immunohistochemically. P450scc and 3 beta HSD were present in all luteal cells of both species. Almost all of the luteal cells were immunostained for P450arom, while P450scc and 3 beta HSD were negatively immunostained in placentae and P450arom was present in the syncytiotrophoblast of placentae. These findings suggest that 1) corpora lutea of both species synthesize pregnenolone, progesterone and estrogen during the entire pregnancy period, and 2) like other terrestrial carnivores in the suborder Caniformia, placentae of both species do not have the capability for synthesizing progesterone in the latter half of active pregnancy period.