Rabbit diarrhea is almost always a sign that something has disrupted the delicate balance of bacteria in your bunny’s gut. The most common triggers are diet problems, parasitic infections, stress, and certain medications. True diarrhea in rabbits is a serious situation that can lead to dangerous dehydration within hours, especially in young or small rabbits, so identifying the cause quickly matters.
Before diving into causes, it’s worth checking whether what you’re seeing is actually diarrhea or something else entirely.
True Diarrhea vs. Uneaten Cecotropes
Rabbits produce two types of droppings. The round, dry pellets you see in the litter box are one type. The other, called cecotropes, are soft, dark greenish-brown clusters that look like tiny bunches of grapes, coated in a shiny layer of mucus. They have a strong smell. Rabbits normally eat cecotropes directly from their body, so you rarely see them. These nutrient-rich droppings are packed with beneficial bacteria that get recycled back into the digestive system.
If you’re finding mushy, grape-like clusters stuck to your rabbit’s fur or scattered around the enclosure, those are uneaten cecotropes, not diarrhea. This is a different (and less urgent) problem, usually caused by too many treats, not enough hay, or obesity making it hard for the rabbit to reach and eat them. True diarrhea is watery or liquid stool, often smeared across your rabbit’s hindquarters. It soaks into bedding rather than holding any shape. If that’s what you’re seeing, the situation is more urgent.
Diet Is the Most Common Cause
A rabbit’s digestive system depends on a steady supply of fiber to function properly. The cecum, a large fermentation chamber in the gut, houses billions of bacteria that break down fiber and produce nutrients. When a rabbit eats too many sugary or starchy foods relative to fiber, those carbohydrates get over-fermented in the cecum. This drops the pH, making the environment too acidic for beneficial bacteria to survive. Harmful bacteria that thrive in acidic conditions, including strains linked to intestinal inflammation, then multiply rapidly.
Research published in Frontiers in Microbiology demonstrated just how dramatic this effect can be. When rabbits were fed diets with a high ratio of non-fiber carbohydrates to fiber, diarrhea rates climbed to nearly 60%, and the death rate reached about 15%. The high-carbohydrate diets also weakened the intestinal lining itself, reducing the proteins that hold gut cells tightly together while increasing inflammation. In practical terms, this means too many pellets, fruit, carrots, or starchy vegetables and not enough hay can set off a cascade that ends in diarrhea.
The fix is straightforward: unlimited timothy hay (or another grass hay) should make up at least 80% of your rabbit’s diet. Pellets should be limited, and sugary treats like fruit or carrots should be occasional, not daily. If your rabbit’s diarrhea started after a sudden food change, that’s very likely the trigger. Any dietary shifts should happen gradually over a week or more to give gut bacteria time to adjust.
Parasitic Infections
Coccidiosis is one of the most common causes of rabbit diarrhea worldwide. It’s caused by tiny parasites that rabbits pick up by ingesting contaminated food or water. There are two forms: one affects the intestines and one affects the liver. The intestinal form is more directly linked to diarrhea. In mild cases, a rabbit may show no symptoms at all. As the infection progresses, the intestinal wall becomes thickened and pale, and loose or watery stool develops.
Young rabbits and those in crowded or unsanitary conditions are most vulnerable. If your bunny was recently adopted, lives with other rabbits, or has access to outdoor areas where wild rabbits pass through, parasites are worth investigating. A vet can diagnose coccidiosis with a simple stool sample. Keeping the enclosure clean and dry, removing soiled bedding promptly, and washing food and water dishes regularly all reduce the risk of reinfection.
Stress and Hidden Health Problems
Rabbits are sensitive animals, and stress alone can trigger loose stool. A new home, a new pet in the household, loud noises, changes in routine, or even rearranging their living space can be enough. Dental problems (where misaligned teeth make chewing painful), urinary tract issues, respiratory infections, and a condition called wry neck (a head tilt caused by inner ear infection) can also cause diarrhea as a secondary symptom. In these cases, the diarrhea is your rabbit’s gut reacting to pain or systemic illness rather than a primary digestive problem.
If the diarrhea started around the same time as any environmental change or your rabbit is showing other signs of illness like reduced appetite, hunched posture, or grinding teeth, the underlying issue needs to be addressed for the diarrhea to resolve.
Antibiotics Can Be Dangerous for Rabbits
If your rabbit recently received medication, that could be the cause. Several common antibiotics are outright dangerous when given orally to rabbits because they wipe out the beneficial gut bacteria while allowing harmful species to take over. Antibiotics that should never be given to rabbits by mouth include amoxicillin, ampicillin, clindamycin, lincomycin, erythromycin, and cephalosporins. This antibiotic-induced gut disruption can cause severe, even fatal diarrhea.
If your rabbit developed diarrhea after starting any medication, contact the prescribing vet immediately. Not all antibiotics are unsafe for rabbits, but the ones that are can cause rapid deterioration.
What to Do Right Now
Diarrhea in rabbits leads to dehydration fast, and a dehydrated rabbit can become dangerously cold because its body loses the ability to regulate temperature. If your rabbit has watery stool, the first priorities are warmth and hydration. Keep your bunny in a warm, quiet space. A towel-wrapped warm water bottle placed nearby (not directly against the skin) provides safe heat.
Remove all food except unlimited hay and fresh water. The hay provides the fiber your rabbit’s gut desperately needs to restabilize, while cutting out pellets, vegetables, and treats eliminates potential irritants. Gently clean any stool from your rabbit’s fur, as a soiled coat attracts flies and can lead to a deadly condition called flystrike within hours in warm weather.
Watch for signs of worsening: lethargy, refusal to eat or drink, a hunched and still posture, or diarrhea that continues beyond a few hours. Baby and juvenile rabbits are especially fragile and can decline within a single day. Adult rabbits with true watery diarrhea (not just soft cecotropes) also need veterinary attention promptly, as the vet can provide fluid support and identify whether a parasite, bacterial overgrowth, or another underlying condition is driving the problem.
Age Makes a Big Difference
Diarrhea in baby rabbits under 8 weeks old is a veterinary emergency. Their small body size means they dehydrate faster, lose body heat faster, and have less immune reserve to fight off infection. Young rabbits being weaned are particularly vulnerable because their gut bacteria are still establishing, making them susceptible to both dietary disruption and parasitic infections. If a baby rabbit has watery stool, warmth and veterinary care within hours, not days, gives the best chance of survival.
Adult rabbits with occasional soft cecotropes and an otherwise normal appetite and energy level are in a much less urgent situation. Adjusting the diet toward more hay and fewer treats typically resolves the problem within a week or two. But an adult rabbit producing truly liquid stool, especially if it’s also lethargic or not eating, needs the same prompt attention as a young one.