The Rig

A rig is an entire male horse with no signs of external testicles so appears to be a gelding; but one or two testicles are still present, producing testosterone. A rig behaves like a stallion and, potentially, may be fertile. Their behaviour is unpredictable and they can be dangerous to handle so they should be castrated. Some geldings still show stallion-like behaviour despite being fully castrated; they are called “false rigs”. The only form of treatment in these cases is behavioural therapy.