Cryptorchid/Testicular Function

Testosterone
Testosterone may be analysed in a single sample if the presence of a whole testicle is suspected. Where testicular remnants or incomplete castration may have occurred it is better to do the hCG stimulation test (listed below).

hCG Stimulation Test

The hCG stimulation test may be used to identify cryptorchidism or testicular function in virtually any species. The following procedure may be used as a guideline; the product data sheet should be consulted for exact doses as required (*).

  1. Take basal blood sample
  2. Inject hCG i/v (Chorulon, Intervet) according to species:
  3. – Equine: 6000 IU
    – Canine: 200 – 500 IU*
    – Feline: 100 – 500 IU*
  4. Take a second blood sample 30 minutes to 2 hours later.
  5. Label both samples clearly and request testosterone.

Interpretation

Animals that have been castrated successfully have low basal levels of testosterone which show little or no increase in testosterone levels following the administration of hCG . Cryptorchid animals show increased basal levels of testosterone which usually increase following the administration of hCG. Animals with normal testicular function should have basal testosterone levels within the relevant normal range and stimulate adequately post injection of hCG.

Oestrone Sulphate (O-SO4) – Equine test for cryptorchidism (Rig Test).
Rig is a behavioural term used to describe a castrated animal showing unexpected male behaviour. A true rig is an animal whose unexpected male behaviour is confirmed to be due to testicular tissue. A false rig is an animal whose unexpected male behaviour is confirmed not due to testicular tissue. Oestrone Sulphate is a single sample test to distinguish between cryptorchids, true and false rigs. The O-SO4 is very accurate but any borderline results will need to be confirmed using the hCG stimulation test. O-SO4 must not be used in donkeys or animals under three years old.

Note: Both O-SO4 and the hCG stimulation test should be used on any animals likely to be the subject of any dispute or court case.

AMH (Anti-Mullerian Hormone)
AMH may also be used as a cryptorchid test to detect testicular tissue and may also be used in young animals under 3 years old. AMH levels should be very low (undetectable) in correctly castrated animals. Other tests (as above) should also be used on any animals likely to be the subject of any dispute or court case.