Preliminary study of ovarian activity in fillies treated with a GnRH vaccine

Objective To investigate the effects of two doses (200 and 400 mg) of a water-soluble gonadotrophin-releasing hormone vaccine on the ovarian activity of 2-year-old fillies.
Design A controlled vaccination dose rate experiment.
Animals Six 2-year-old Australian Stock Horse fillies were randomly allocated to three treatment groups: unvaccinated controls, those receiving 200 mg of the vaccine and those receiving 400 mg of the vaccine.
Results Ovarian activity of the treated fillies was suppressed at the peak of the breeding season while that of the untreated controls continued normally. The control fillies displayed oestrous activity and behaviour. Suppression of ovarian activity occurred for 25 and 30 weeks in the 200 and 400 mg groups, respectively. These differences were not significant. Ovarian activity ceased 2 to 3 weeks after primary vaccination. Antibody titres were low (330) until after the booster immunisation when they rapidly peaked at 22,000 and 28,000 in the 200 mg and 400 mg groups, respectively. Plasma progesterone concentrations of the treated fillies remained below 3.18 nmol/L while GnRH was suppressed. The vaccine had no significant effect on plasma androstenedione concentrations. Recovery from the effect of the vaccine was associated with development of ovarian follicles, normal oestrous behaviour and ovulation. Three of the four treated fillies and one of the controls conceived during the next breeding season and foaled normally. All the treated fillies conceived and produced normal foals in the following two breeding seasons.
Conclusion Both dose rates suppressed ovarian function and prevented oestrous behaviour. These effects were reversible and the subsequent fertility of the vaccinated fillies was normal.     

A NEW DEVICE FOR STEREOTACTIC CT-GUIDED BIOPSY OF THE CANINE BRAIN: DESIGN, CONSTRUCTION, AND NEEDLE PLACEMENT ACCURACY

An inexpensive device was created for computed tomographic (CT)-guided stereotactic biopsy of the canine brain. The accuracy of the device was tested using 16, formalin-perfused, canine head specimens. For each dog, a 6-inch biopsy needle was guided into pituitary gland and caudate nucleus targets. Needle tracks were measured using the CT computer and infused with tissue staining solution. Hit success and actual needle track lengths were determined from sliced brain specimens. The device enabled accurate orientation and placement of the canine head in the slice plane, such that progressive penetration of the biopsy needle could be monitored. The caudate nucleus was hit 12/16 times (75% accuracy) and the pituitary gland 15.5/16 times (98.6% accuracy). Hit proportions for the two targets did not differ (P < 0.05). A significant difference was found between CT and actual track length for both targets (P < 0.01). This was attributed to incomplete staining of the bevel portion of the needle track.     

Effects of Retinoids on the In Vitro Development of Capra Hircus Embryos to Blastocysts in Two Different Culture Systems

The objective of this study was to evaluate the effect of retinol (RT) and retinoic acid (RA) on the in vitro development of pre‐implantation goat embryos cultured in potassium simplex optimized medium or synthetic oviduct fluid or cocultured in oviductal cells monolayer either in potassium simplex optimized medium or synthetic oviduct fluid. A total of 2407 cumulus‐oocyte complexes were aspirated from 2 to 6 mm ovarian follicles from slaughtered animals. Selected cumulus‐oocyte complexes were subjected to in vitro maturation in TCM 199 for 24 h at 39°C in an atmosphere of 5% (v/v) CO₂ in humidified air. In vitro fertilization was performed in modified defined medium. Eighteen hours after in vitro fertilization, cumulus cells were removed and presumptive zygotes were randomly distributed into experimental groups. In Experiment 1, presumptive zygotes were cultured in potassium simplex optimized medium, potassium simplex optimized medium + RT, potassium simplex optimized medium + retinoic acid, synthetic oviduct fluid, synthetic oviduct fluid + RT and synthetic oviduct fluid + RA at 39°C in a humidified atmosphere of 5% (v/v) CO₂, 5% (v/v) O₂ and 90% (v/v) N₂. In Experiment 2, presumptive zygotes were cocultured in potassium simplex optimized medium + oviductal cells monolayer, potassium simplex optimized medium + RT + oviductal cells monolayer, potassium simplex optimized medium + RA + oviductal cells monolayer, synthetic oviduct fluid + oviductal cells monolayer, synthetic oviduct fluid + RT + oviductal cells monolayer and synthetic oviduct fluid + RA + oviductal cells monolayer in an atmosphere of 5% (v/v) CO₂ in humidified air. In both experiments, media were partially changed on day 2 after in vitro fertilization and unfertilized oocytes were excluded from the experiment. Embryos were cultured or cocultured for 8 days. In Experiment 1, there was no effect of RT or RA supplementation on the proportion of oocytes that reached the morula or blastocyst stages. By contrast, Experiment 2 demonstrated that the addition of 0.28 μg/ml RT and 0.5 μm RA to the embryo culture media stimulated (p < 0.05) development to the morula and blastocyst stages under the coculture conditions tested. In conclusion, retinoids play an important role in pre‐implantation development of goat embryos and can be used to enhance in vitro embryo production.