Luteal Function in the Domestic Cat during Pseudopregnancy and after Treatment with Prostaglandin F2α

Abstract

The effect of PGF2α 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 F2α-tromethamine (PGF2α) 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 PGF2α 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-17β levels, were not affected by treatment with PGF2α.