Embryo transfer in the cat during the non-breeding season.

Studies were conducted to investigate the possibility of embryo transfer in the cat during the non-breeding season. Estrus was induced in 19/22 (86.4%) cats using a porcine pituitary gland preparation. Uterine horns were flushed in 5 cats 6-8 days after mating with expanded blastocysts being collected from 4 cats. One to nineteen blastocysts per cat were transferred to the uterine horns of 6 recipient cats in which ovulation had been induced with HCG. The time differences between time of ovulation in donor and recipient animals were 0.5 days earlier in the recipient (2 cats), 1 day later in the recipient (3 cats), and no difference (1 cat); conception occurred in all the recipients. The ratio of fetuses to transplanted embryos were 1/1, 1/2, 2/3, 2/6, 4/7, and 2/19, respectively. Fetal death occurred in 2 cats at days 22 and 25 and abortion occurred in 3 cats at days 34, 35 and 39. There was a delay in the expulsion of placentae in the animals that experienced fetal death on days 22 and 25, expulsion occurring on days 36 and 56, respectively. One cat was treated with progesterone and carried 2 fetuses to day 66; pregnancy was terminated by cesarean section. In conclusion, it was demonstrated that embryo transfer can be performed in cats in which estrus and ovulation have been induced with porcine pituitary gland preparation during the non-breeding season. However, luteal activity needs to be supplemented by exogenous progesterone administration to maintain pregnancy.