Mare Breeding and the Progesterone Test
Short answer
The progesterone test measures a hormone in a mare's blood that follows her breeding cycle. A vet uses it with an ultrasound scan to plan breeding, but it cannot confirm a pregnancy on its own.
For: Horses Adult Horse
By Pashupatinath Vet Lab Share
The progesterone test measures a hormone in a mare's blood that rises and falls with her breeding cycle. It can help a vet judge whether a mare has ovulated and plan breeding, together with an ultrasound scan. It cannot confirm a pregnancy on its own. A registered veterinarian reads the result with the scan and the mare's history.
What happens in a mare's breeding cycle?
A mare that is not in foal goes round a repeating cycle. For some days she is in heat, which vets call oestrus. She accepts the stallion, and towards the end of the heat an egg is released from a follicle, a small fluid-filled sac on the ovary. The release of the egg is called ovulation.
After ovulation the empty follicle turns into a yellow body that makes progesterone. The mare now stops showing heat. If she does not become pregnant, the yellow body fades, progesterone falls and she comes back into heat. If she is pregnant, progesterone stays high in the early months.
Quiet heats are easy to miss in a stable. Note the dates when you see signs of heat and share them with your vet.
What does the progesterone test show?
The Equine Progesterone test measures the hormone in serum, the clear part of blood. A low level usually fits a mare who is in heat or has not yet ovulated. A higher level usually fits a mare who has ovulated and has an active yellow body. The lab report shows the reference range, and your vet reads the figure against the stage of her cycle.
A single result is only a snapshot. Your vet may take a second sample later to see which way the hormone is moving.
The test is commonly used to:
- find out whether a mare who shows no heat is cycling at all
- check that ovulation has taken place after a heat
- help plan the right time for covering or insemination
- look into why a mare that was bred has not settled, as one piece of the picture
How does a scan fit in?
The scan is the main tool in horse breeding. Your vet passes a small ultrasound probe through the rectum to see the follicles growing on the ovaries and to check the womb. Later, the same kind of scan shows whether a pregnancy has started.
The blood test adds what the scan cannot show, which is what the hormones are doing. Used together, the two give a clearer picture than either one alone. The vet decides the timing; the test does not decide it by itself.
Some vets also ask for a Complete Blood Count (CBC) before breeding. It counts the red cells, white cells and platelets, and may show anaemia, which means too few red cells, or signs of infection. It helps the vet judge the mare's general health.
The Mare & Foal Check Pack typically brings the progesterone test and a CBC together with a foal IgG test, which checks the protection a newborn foal gets from the mare's first milk. The exact list is confirmed when you book.
What can the test not tell you?
- It does not confirm a pregnancy. A mare that is not pregnant also has high progesterone after ovulation. Only the vet's scan or examination can confirm one.
- It does not give the exact hour of ovulation.
- It does not show infection in the womb or a problem with the stallion's semen. Other examinations and tests are needed for those.
- A normal result is not a promise of a foal.
Hormone results depend on careful handling. Your vet draws the blood from the neck vein, and the serum should be separated and kept cool as the lab advises, because blood left in the heat can give an unreliable result. Write the mare's name, the date and the stage of her cycle on the form so the vet can read the number properly.
Read next
Some stables, events and authorities ask for a blood test before a horse moves, and What Is Equine Infectious Anaemia and the Coggins Test? explains one such test. To see why timing and handling matter for any sample, read Why a Lab May Ask for a Fresh Sample.
Testing in Bhopal
Ask your vet to draw the blood, then call or WhatsApp +91 88175 01118 and the lab will arrange free collection from your stable anywhere in Bhopal. The lab is at C-200, C Sector, Shahpura, and it confirms the method, sample needs and reporting time when you book. Stud farms in other districts can send serum by courier or bus parcel, or pass it to their own vet to forward.
This article is general information and does not replace a veterinarian’s advice. Please talk to a registered veterinarian about your animal’s signs, tests and treatment.