Search

An acute phase response has been identified during mid-gestation in bitches by determination of the serum C-reactive protein (CRP) concentration. In four pregnant bitches, a large increase in CRP during mid-gestation was followed by a second increase after parturition. In three pregnant bitches, a similar increase was observed during mid-gestation but the second (post parturition) increase was not detected. In two pregnant bitches only a small rise was observed in mid-gestation. No increase in CRP was observed in the serum of two bitches that were not mated following oestrus or in the serum of two bitches that were mated but did not become pregnant. One bitch was diagnosed as pregnant by palpation but did not produce a litter and did not have a mid-gestation increase in CRP. However, this animal did show an acute phase response shortly after oestrus.

Oocytes were collected from ovaries of bitches, at various stages of the oestrous cycle, after routine sterilization. Cumulus-enclosed oocytes were cultured for 0-72 h in a modified M-199 medium containing 10% oestrous bitch serum and 20 micrograms oestradiol ml-1. For oocytes surrounded by two or more layers of cumulus cells, an increase in the expression of mRNA transcripts for zona pellucida glycoprotein 3 (ZP3) was seen and reached peak levels after 48 h culture in vitro. Histological assessment showed that 39% of these oocytes had extruded their first polar body after 24 h culture in vitro. When these in vitro matured oocytes were transferred to oviduct cell monolayers and inseminated with fresh dog spermatozoa in Medium-199 supplemented with 10% fetal calf serum and 50 mg gentamicin sulfate ml-1, penetration of the zona pellucida started 1 h after insemination for oocytes that had been cultured for 48 and 72 h. At 12 h after insemination both male and female pronuclei were seen in 37.5% and 20% of the oocytes incubated for 48 and 72 h, respectively. No further development was seen.

Medroxyprogesterone acetate (MPA) was administered as a depot injection to two adult male dogs. One was injected with 75 mg as a depot injection once a month for 2 months and the other with 50 mg at 2-weekly intervals for 1 month, followed by 100 mg at 2-weekly intervals for a further 2 months. Two other male beagles were given gonadotrophin-releasing hormone (GnRH) agonists (nafarelin derivative no. 49947 and nafarelin acetate) at a dose of 50 micrograms day-1 for either 22 or 23 days. The profiles of luteinizing hormone (LH) and testosterone were monitored before and during the treatment periods, and changes in the dogs' testes, epididymides and prostate glands were determined post mortem. In the MPA-treated animals, LH was suppressed for only very brief periods. In contrast, in the dogs treated with GnRH agonist, LH and testosterone concentrations were suppressed for most of the treatment period. In the MPA-treated animals, histological changes were seen mainly in the head of the epididymis, and in the acrosome region of the spermatozoa still present in this region of the male reproductive tract. The acrosome, instead of being closely applied to the sperm head, was in contact only in the most anterior areas, with the remainder forming a fan-like projection, indicating increasing detachment from the sperm head. In the dogs treated with GnRH agonist there was clear evidence of cessation of normal spermatogenesis in most of the seminiferous tubules. Changes in the histology of the head of the epididymis were similar to (but more profound than) those found in the dogs treated with MPA. Seminal changes were demonstrated in ejaculates collected during the latter stages of the treatment period.

Real-time B-mode ultrasound imaging was carried out, using a scanner of moderate quality, on 40 fresh bitch cadavers to identify the presence of ovaries and significant ovarian structures. The results indicated that accurate identification of the ovaries depended on the presence of significant follicles or corpora lutea (CL). The findings were verified at post-mortem examination. The study was continued by scanning 35 live bitches using three different scanning units of increasingly improved quality to show that the process of ovulation could be assessed with reasonable accuracy with improved quality of equipment, although the exact fate of the follicle could not be imaged. The results were judged against assays for blood circulating progesterone. A final group of seven live bitches were scanned with a high-grade scanner using an annular phased-array transducer to attempt to image the process of ovulation. The non-echogenic follicle disappeared and was replaced by the CL that was hypoechoic with respect to surrounding tissue, thus allowing accurate assessment of the time of ovulation. This was confirmed by progesterone assay.

Behaviour, vaginal cytology and plasma progesterone concentrations were monitored during oestrus in a group of 6 beagle bitches before intrauterine insemination with frozen semen. At intervals after insemination, the reproductive tracts were examined for evidence of conception, which occurred in 5 of the bitches. One pregnant bitch had received treatment with stilboestrol before insemination.