Guinea Pig Rectal Prolapse: Emergency Causes, Treatment, and Recovery

See your vet immediately. A rectal prolapse happens when tissue from the rectum protrudes through the anus. In a guinea pig, this often looks like a moist pink or red tube of tissue at the rear end. As swelling, drying, and trauma increase, the tissue can become darker, firmer, ulcerated, or even necrotic.

Rectal prolapse is not a diagnosis by itself. It is usually a sign that your guinea pig has been straining repeatedly. That straining may come from diarrhea, intestinal inflammation, parasites, constipation, urinary tract pain, bladder stones, or another problem affecting the belly or pelvis.

This is considered an emergency because exposed tissue can dry out quickly, lose blood supply, and become harder to save. Fast treatment gives your vet the best chance to reduce the prolapse, protect the tissue, and address the cause before the problem recurs.

Rectal prolapse usually develops after repeated straining, also called tenesmus. In guinea pigs, one of the most common pathways is gastrointestinal upset. Diarrhea, colitis, intestinal irritation, sudden diet change, low-fiber feeding, or parasite-related inflammation can all increase straining. Young animals and pets with severe diarrhea may be at higher risk.

Other causes are outside the colon itself. A guinea pig that strains to urinate because of cystitis, sludge, stones, or another urinary problem may also prolapse rectal tissue. Constipation, painful defecation, foreign material, masses, or trauma around the rectum can contribute too. In some cases, your vet may also consider poor body condition, dehydration, or weakened tissues as factors that make prolapse more likely.

Diet matters as well. Guinea pigs need constant access to grass hay and a reliable vitamin C source. Inadequate vitamin C can contribute to poor tissue health and diarrhea, while low-fiber feeding can disrupt normal gut movement and stool quality. That does not mean every guinea pig with a prolapse has a diet problem, but nutrition is an important part of prevention and recovery.

Your vet will usually diagnose a rectal prolapse based on the physical exam. The appearance of a tubular mass protruding from the anus is often enough to identify the problem. Your vet will also assess whether the tissue is still viable, how swollen it is, and whether it appears to be a partial mucosal prolapse or a more complete prolapse involving deeper layers.

The next step is finding out why your guinea pig strained in the first place. Depending on the history and exam findings, your vet may recommend a fecal test for parasites, abdominal imaging, urinalysis, or bloodwork. In guinea pigs, this workup can be especially important if there is diarrhea, weight loss, reduced appetite, urinary straining, or concern for bladder stones or other painful abdominal disease.

Your vet may also need to distinguish rectal prolapse from other conditions that can look similar, such as prolapsed intestinal tissue or severe swelling around the anus. That distinction matters because treatment and prognosis can change quickly if the tissue is not healthy or if a deeper intestinal problem is present.

Prevention focuses on reducing straining. Feed unlimited grass hay, use a high-quality guinea pig pellet, and provide fresh vegetables that support vitamin C intake. Because vitamin C breaks down over time, pellets should be fresh, and many guinea pigs benefit from direct oral vitamin C supplementation if your vet recommends it. Good hydration and a high-fiber diet help support normal stool quality and gut movement.

Watch closely for diarrhea, reduced appetite, weight loss, painful urination, or repeated posturing to pass stool. These are not problems to monitor for days at home in a guinea pig. Early veterinary care for digestive upset, parasites, urinary disease, and dental problems can prevent the repeated straining that leads to prolapse.

Clean housing also matters. Remove soiled bedding promptly, keep food and water containers clean, and schedule routine wellness visits with your vet, especially if your guinea pig has had prior digestive or urinary issues. If your guinea pig has already had one prolapse, follow every recheck recommendation closely because recurrence is most likely when the original trigger has not been fully controlled.