Guinea pigs are unlike other small mammals in the area of reproduction. Most small mammals can be bred at any time during their life without many complications. In the guinea pig, also known as the cavy, this is not always the case.
Both male and female guinea pigs reach puberty around 3 to 4 months of age. At this point, it is time to breed your female for the first time. This may seem a little young but guinea pigs bred after 7 months of age for the first time can have significant health problems.
During delivery, the bones of the pelvis need to be able to widen to allow the pups to pass through. Guinea pig pups tend to be quite large when born and birthing problems can easily occur. In those cavies that are not bred before 7 months of age, the developing pelvic bones will fuse together. This results in a normal sized pelvis that isn't particularly flexible. Large pups that try to pass through this fused pelvis can have problems. The sow may strain and bleed, unable to pass the pup through the birth canal. By breeding your cavy for the first time before 7 months of age, the pelvis remains flexible throughout life and delivery problems become uncommon.
As the pregnancy progresses, various hormones are released. One important hormone is relaxin. This hormone helps widen an unfused pelvis, allowing for easy passage of the pups. Under the influence of relaxin, the pelvis will fuse but is fused with cartilage rather than bone. This allows for future widening of the pelvis in subsequent pregnancies. This hormone, unfortunately, is not effective on a pelvis already fused with bone.
If your sow is bred for the first time after 7 months of age, dystocia (difficult birth) is a significant risk. Sows will strain and may have a bloody uterine discharge. Pups are generally born within 30 minutes. Straining longer than that should prompt an exam by a veterinarian.
The treatment for a guinea pig having difficulty delivering babies starts with medication. Initially, oxytocin can be given. This hormone will stimulate uterine contractions and can help the sow deliver the pups. If no pups are born within around 30 minutes, it is time for surgery.
Cesarean section is performed under general anesthesia. The pups are removed from the uterus. At this point, the incision in the uterus can be closed with absorbable suture or the uterus and ovaries are removed, resulting in spaying.
Despite having a cesarean section, the guinea pig is typically able to nurse the pups as normal.
Pregnancy toxemia is another concern for the pregnant sow. Though the exact cause of this illness is unknown, overweight sows during their first and second litter are more at risk. Signs of toxemia generally develop from two weeks before birth up to about one week after delivery.
Sows with toxemia have a lack of appetite, weakness, depression, incoordination, difficulty breathing, coma and possibly death. It appears that obesity and stress play an important role in the development of toxemia. By keeping your sow at a proper weight and not allowing a pregnant sow to become overweight, the risk of toxemia can be reduced. Unfortunately, many sows do not respond to treatment. Prevention is crucial in maintaining health of your guinea pig.