Should my guinea pig be neutered or spayed?

Short answer: not necessarily for single pigs or harmonious same-sex pairs. If boars and sows will share a cage or floor time, neutering is strongly recommended — usually the boar, as the surgery is simpler.

1. Mixed-sex risks — guinea pigs breed very easily and sows can conceive again shortly after giving birth; sows that have not bred by 6–8 months develop a fixed pelvis, making later pregnancy and birth high-risk.

2. Neutering boars — a relatively simple procedure with 1–2 weeks of recovery; keep him apart from sows for 4–6 weeks afterwards, as residual sperm can remain. Spraying and scent-marking may lessen, though personality may not change.

3. Spaying sows — an abdominal surgery with higher anaesthetic and surgical risk; most exotic vets recommend regular check-ups and an individual assessment.

4. Anaesthesia — guinea pigs are sensitive to anaesthesia and lose body heat quickly; choose an experienced exotic-animal vet and complete a pre-surgery weight and health check.

5. Aftercare — keep the space clean and warm, use soft dust-free bedding and watch the incision and appetite; return to the vet promptly if eating drops noticeably.