Horse Side Vet Guide ®

Equine Health Resource

Mare in Heat, Normal Estrus

During the breeding season (April through October in the northern hemisphere), a mare’s heat cycle is 21 days long, 7 days of which she is in estrus.

Mares in heat display a variety of distinct behaviors. Some mares show obvious signs, while others show no outward evidence of being in heat. If a mare does not show outward signs, the only way that she can be diagnosed as “in estrus” is with a veterinary examination or exposure to a stallion.

Classic estrus behavior includes “winking” of the vulva, urinating and squatting. Receptive mares stand well for a stallion. Unreceptive mares do not.

There are a variety of reasons why mares in estrus do not show estrus behavior.

Author: Doug Thal DVM Dipl. ABVP


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