No. In mammals such as sheep, dogs, cats, cows, and horses, menstruation (or period) does not occur.
What most mammalian placental females experience is the estrous/oestrous cycle - the reproductive cycle whereby there are recurring periods when the female is fertile and receptive for mating (estrus). It is interrupted by periods in which the female is not fertile and not receptive (anestrus).
Animals that have estrous cycles reabsorb the endometrium (inner membrane of the mammalian uterus) if conception does not occur during that cycle.
The estrous cycle is contrasted with the menstrual cycle in which the endometrium is shed through menstruation when pregnancy does not occur and in which the female may be receptive for mating at any time during the cycle.
In sheep, the length of the estrous cycle ranges from 13 to 19 days and averages 17 days.
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