Healthy guinea pigs pass both firm and soft pellets each day. They consume the soft cecal pellets directly from their anus as an important source of B vitamins. The hard pellets get left behind in the cage. You'll know your cavy is constipated by the absence of feces in the cage or if you see him straining to pass feces without any results. Feeding your guinea pig leafy green vegetables high in both fiber and moisture is the first step toward correcting constipation.
Check His Diet
Your guinea pig's daily diet should contain hay, clean water and fresh greens. Pellets provide vegetable matter combined with vitamin C, but if your cavy eats too many in proportion to his regular diet he may get constipated. Reserve fruits for occasional snacks as high sugar content upsets the digestive process. If he's having difficulty passing feces, low-sugar fruits such as a piece of unpeeled apple or or pear peel can provide relief. Putting a few drops of olive oil on a treat he enjoys can also help move things along.
Don't administer olive oil directly with a syringe, as this may cause aspiration of the oil into the lungs.
Check for Impaction
Obese or pregnant guinea pigs sometimes can't reach their anal openings to ingest cecal feces. Older guinea pigs can also lose muscle tone, trapping the feces in anal pockets they can't reach. The feces plug the anal opening, preventing both cecal feces and fecal pellets from passing. If a guinea pig isn't able to ingest his cecal matter, his general health will suffer. You can help a guinea pig pass feces stuck in the anus by manually expressing the matter. Wear rubber gloves and use warm water or olive oil to soften the impacted feces. Do not attempt to insert oil into the rectum using a syringe, as this can injure the guinea pig. Gently press around the anal opening to help the ball of feces work its way out. You may have to repeat this on a daily basis or clean a cavy's bottom on a daily basis if he can't do it for himself. Your veterinarian can prescribe supplements to replace the vitamins your pet is missing if he can't eat his cecal feces.
Consult with your vet before attempting to manually express fecal matter from your guinea pig.
If your guinea pig hasn't passed feces in 12 to24 hours, call your veterinarian's office for an exam. Some species of fly lay eggs in impacted fecal matter and the hatching maggots can kill the guinea pig by boring into its flesh. Should your guinea pig appear bloated, act lethargic or seem to be in obvious distress, call your vet's office immediately. Constipation could be a symptom of a life-threatening condition such as internal blockage, parasites or infection.