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Diagnostic
Tests or procedures used by your vet to determine what is wrong with your horse, in order to reach a diagnosis.

Cost: $100 to $500

These cost ranges are approximate and may vary from region to region.
Additional charges may also apply.

YOUR VET MAY PERFORM

Testosterone Level in Serum

Cost: $100 to $500

These cost ranges are approximate and may vary from region to region.
Additional charges may also apply.

Summary

Testosterone is the hormone responsible for stallion sexual behavior. It is also responsible for stallion-like appearance, the so called secondary sex characteristics of heavy muscling in the neck and jowels.

Testosterone testing is usually done in geldings that are showing stallion-like behavior. It involves taking a sample of blood and submitting it to a laboratory. A positive test indicates that the horse has testicular tissue and may warrant surgical exploration for a retained testicle. While a retained testicle does not usually produce viable sperm, it does continue to produce testosterone.

(It is not considered acceptable veterinary practice to only remove one testicle during a castration, but unfortunately it does occur. Vets typically examine a stallion prior to castration to ensure that both testicles are present and down.)

Why A Vet Chooses This Diagnostic

BENEFITS
A low value of testosterone usually indicates that the horse is a gelding. A high value indicates the presence of testicular tissue.

LIMITATIONS

There are cases in which the testosterone result is on the high side for a gelding and on the low side for a stallion. In those cases, modified tests of other hormones (estrone sulfate) or what is called an HCG stimulation test are recommended to provide greater certainty.

your role

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Questions To Ask Your Vet:
  • Does this test confirm that there is actually testicular tissue present in my horse?
  • Are other tests necessary to confirm?

Author: Doug Thal DVM Dipl. ABVP