PREGNANCY FAILURE IN CATS ASSOCIATED WITH LONG-TERM DIETARY TAURINE INSUFFICIENCY

The effect of long-term dietary taurine insufficiency on reproductive function was studied in adult female domestic cats (n = 11). Cats were time-mated during taurine-deficient (6 months) and refed (6 months) s tates, and the outcome of ovulatory cycles and breeding was analysed. Serum progesterone and relaxin concentrations were evaluated in order to characterize pregnancies, including those resulting in resorption o f fetuses, and pseudopregnancies. Increased resorption of fetuses, red uced litter size, and increased incidence of stillborn kittens was obs erved in queens while on taurine-deficient diets, as well as after ref eeding of a taurine-enriched diet. Overall, 30% of the ovulatory cycle s resulted in the delivery of kittens, with mean live and stillborn li tter sizes of 2.2 +/- 0.4 and 0.8 +/- 0.4 kittens (mean +/- SEM), resp ectively. The remaining ovulatory cycles resulted either in pregnancie s in which fetuses were resorbed (38%), or in pseudopregnancies (32%). Ovulatory cycles resulting in resorbed fetuses were characterized by the appearance of relaxin on day 20 of gestation, but with a subsequen t decrease to non-pregnant concentrations by day 25 of gestation. Thes e results suggest that reproductive failure in domestic cats exposed t o long-term nutritional taurine deficiency is associated with a postov ulatory defect manifest within the first 10 days after implantation, a nd that this defect is not reversible upon refeeding of a taurine-enri ched diet for 6 months.