What you see. The starting point for addressing any equine health related issue is your observation.


Mare Doesn't Show Signs of Heat


During the breeding season (April through October in the northern hemisphere), mares should be in obvious heat approximately 5 days out of each 21 day cycle. Many mares show outward signs of heat during estrus, even without being exposed to a stallion. Most should show obvious signs of estrus when exposed to a stallion.

In this case, you expect your mare to be in heat but she fails to show any sign of estrus. When exposed to a stallion she is not receptive. You have tried this several times and she consistently appears unreceptive.

There are several things that could be going on. The mare might truly not be in heat, or she may be coming into heat but not behaving as though she is. This is known as silent heat or behavioral anestrus.

  • Code Orange

    Call Your Vet at Their First Available Office Hours
    • You hope to breed the mare as soon as possible.
  • Code Yellow

    Contact Your Vet at Your Convenience for an Appointment
    • There is no hurry in breeding the mare.

your role


What To Do

Assess the mare's general health using the Whole Horse Exam (WHE), paying particular attention to her body condition score (BCS). Check the vulvar area for any obvious abnormalities and look for discharge. Consider whether there is a possibility she is already pregnant.

your vet's role

Your vet will start with rectal palpation and ultrasound of the mare's reproductive tract. The results of those diagnostics will provide the basic information to determine a path for managing the problem.
Questions Your Vet Might Ask:
  • Does the mare have a foal at her side?
  • Are you exposing the mare to a stallion?
  • Has the mare had prior foals or is she a maiden?
  • What is the mare's age, breed and history?
  • Can you identify when your mare is in heat versus not?
  • Have you ever seen the mare in heat before?
  • Does the mare appear normal otherwise?
  • What is the mare's body condition and feeding now?

Treatments Your Vet May Recommend

A way to resolve the condition or diagnosis. Resolving the underlying cause or treating the signs of disease (symptomatic treatment)

Very Common
more treatments

Author: Doug Thal DVM Dipl. ABVP