OPTIMIZING BREEDING EFFICIENCY IN THE DOMESTIC DOG

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The current social trend against the use of random source dogs in biomedical research indicates that efficient methods of reproducing domestic dogs for laboratory purposes are urgently needed. New methods should be investigated which would augment controlled breeding since spontaneous natural mating occurs only one or two times a year in the domestic bitch, and previous attempts to induce this event have produced variable results. The present proposal is directed toward four objectives: 1) the induction of ovulation by utilizing a regimen of repetitive pulses of gonadotropin releasing hormone; 2) characterization of endogenous gonadotropin pulse patterns throughout the reproductive cycle; 3) an abbreviation of the normal metestrous period and attenuating the post-lactational effects of prolactin with treatments of prostaglandin F2Alpha and bromergocryptine, respectively; and 4) the early detection of pregnancy by quantifying plasma estrogen levels using an in vitro, cytosol receptor-binding assay for total estrogens. These studies will provide critical baseline information relating to spontaneous ovulation in the bitch while establishing the utility of gonadotropin releasing hormone as a treatment for advancing ovulation and optimizing conception. Additional information will be obtained which pertains to the mechanisms associated with luteal function and lactation by two separate strategies which are designed to further shorten the interbirth interval. These studies will be documented by hormonal data. Finally, a retrospective analysis of pregnant and non-pregnant, post-estrus bitches will investigate the potential of a chemical test for detecting pregnancy. Preliminary studies by the applicants demonstrate that a novel strategy to induce ovulation can be successfully employed in the domestic dog. Although not yet well-developed, this approach provides the colony manager with the ability to successfully breed anestrous bitches at will.