If you have guinea pigs, you will almost always face the question of castration or spaying.
Guinea pigs reproduce very quickly. After a short gestation period of 59 to 72 days, a female is ready to become pregnant again immediately after giving birth.
If you have a harem (one male with multiple females) or only males, castration is necessary.
If you keep males and females together, castration is essential!
If you have only females together, there is no need to worry about castration or spaying.
**Harem – One Male with Multiple Females
Castration of the male is mandatory. Without it, uncontrolled breeding can occur very quickly, something an inexperienced owner may not be able to manage. The situation can spiral out of control!
If you have multiple females with one or more males, it usually makes sense to castrate the males, partly because castration is easier and less risky in males than in females.
Female guinea pigs generally only undergo spaying (ovariohysterectomy – removal of ovaries and uterus) if it is medically necessary. This may be required in cases such as tumors or infections.
**Two or More Males Together
Castration can also be useful if you have only male guinea pigs. Castration is often performed preventively to avoid conflicts later. Castrated males are calmer, and potential issues between them do not arise. If males no longer get along, performing castration afterward is usually pointless; the animals would need to be separated and rehomed with other guinea pigs.
Even if males cannot always stay in a male-only group, castration may still be advisable. As guinea pigs age, castration becomes less common. If a male is not castrated, he will not be allowed to join females as he gets older. A castrated male, however, can always be introduced to female guinea pigs.
On our pages, we often encounter uncastrated males looking for a home. Finding a suitable home for them is very difficult. Castrated males would find a home much faster, especially with females.
Always consult a veterinarian experienced with guinea pigs!
After castration, the castrated male must remain isolated for 6 weeks, away from females, because he can still be fertile during this period. This can be a drawback, as the animal may need to stay alone if no compatible male is available. Therefore, early castration can be an alternative.
**Early Castration: Yes or No?
Early castration is performed before sexual maturity, typically between 3 and 6 weeks of age. Weight is also considered: the guinea pig should be around 250–300 grams. The advantage of early castration is that the animal does not need to be separated from females when reaching sexual maturity, and after the 6-week recovery period, it does not need to live alone.
**Why Castration in Older Guinea Pigs Should Be Avoided?
Castration in older guinea pigs (over 3 years old) is generally not recommended. Anesthesia always carries risk, and in older animals, the likelihood of complications or death under anesthesia increases.
