Actually, they can -- either procedure can be performed by an exotic veterinarian (one who specializes in small/exotic animals).
The surgery to spay females is more invasive, and is more commonly reserved for cases when there is a life-threatening problem involving the pig's reproductive system. If you want to keep a male and female guinea pig together, neutering the male is the preferred option.
There are some guidelines for neutering, which you can find over at Cavy Spirit. Some highlights of these guidelines include:
- The guinea pig should be at least 4 months old.
- Avoid putting senior pigs (older than 4 years old) through the stress of surgery unless it's medically necessary. Cindy actually tries not to put guinea pigs older than 3 years old through surgery unless it's medically necessary to save the animal.
- Getting one or both males in a pair neutered to make the dominant pig less dominant is a strategy that carries few guarantees. Personality is personality.
- Keep a newly neutered male guinea pig separate from his female friend for 3 to 4 weeks. The vets at South Wilton Veterinary Group recently told us that papers have been published that say that males actually should be kept separate from females for 4 to 6 weeks after they've been neutered.
And, finally, understand that while hundreds of neutering procedures are successfully performed on guinea pigs nationwide every month, any surgical procedure carries risks for animals. These are risks that owners should know about and be prepared for. The link to Cavy Spirit (above) discusses these risks in detail, and a good exotic veterinarian will be willing to spend time explaining a procedure to you.