Biology of Reproduction, Vol 21, 1217-1223, Copyright © 1979 by Society for the Study of Reproduction

Luteal Function in the Domestic Cat during Pseudopregnancy and after Treatment with Prostaglandin F₂

¹ Department of Reproduction, School of Veterinary Medicine, University of California, Davis, California 95616

The effect of PGF₂ treatment on luteal function was studied in cats made pseudopregnant by coitus with vasectomized males. Luteal function was determined by the measurement of plasma progesterone. In 7 cats (12 cycles), prostaglandin F₂-tromethamine (PGF₂) was administered s.c. every 12 h on Days 11-15 or 21-25 postcoitum using doses of 220 or 440µg/kg (3 cycles/treatment). In untreated cats the mean interval from coitus to the start of the subsequent estrus was 45.4 days (SD = 8.0, n = 37) and the average period when mean plasma progesterone levels remained above 1 ng/ml was 37.4 days (SD = 5.1, n = 16). The responses to the 2 dose levels were not different and the data were pooled for this factor. The interval from coitus to subsequent estrus and the duration of the luteal phase were not significantly (P>0.1) affected by PGF₂ treatment. Progesterone concentrations, while not significantly (P>0.1) depressed during the Day 11-15 treatment period, rose subsequently to significantly (P<0.05) higher concentrations when compared with controls on Days 33 and 36 postcoitum. A significant (P<0.05) depression of progesterone content in plasma occurred during the treatment on Days 21-25. Follicle growth patterns, as indicated by plasma estradiol-17 levels, were not affected by treatment with PGF₂.

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ACKNOWLEDGMENTS This work was supported in part by the Animal Protection Institute of America, Sacramento, CA and Companion Animal Laboratory Research Program, School of Veterinary Medicine, University of California, Davis.