Horses 3 years or older

In this group, a single test for oestrone sulphate will distinguish between rigs and geldings. The equine testis is unusual in that it produces more than 10 times as much oestrogen as testosterone. In this group it is recommended that oestrone sulphate levels be measured as commercially available testosterone kits are not sensitive enough to detect the small variations in baseline testosterone between geldings and rigs.

Sample Requirements for Oestrone Sulphate

2.5 ml of blood in a plain (clot) tube.

Horses 2 years or younger & donkeys of any age

In this group dynamic screening of testosterone with a hCG stimulation test levels is the recommended procedure.

Protocol and Sample Requirements for the hCG Stimulation Test

1. Collect 5 ml of blood in a plain (clot) tube.
2. Inject at least 6000 IU of hCG IV (always check the product sheet for accurate dosing rates and precautions).
3. Wait 30 minutes to 2 hours.
4. Collect 5 ml of blood in a plain (clot) tube.
5. Make sure that both tubes are accurately labelled.

Other Species:

The hCG stimulation test can be used to detect cryptorchidism in other species, but the dose of hCG required will vary. Consult the package insert for more dose details and precautions.

DCI-04 Rigs vs Geldings (V2.1, 30-12-2003)