Colibacillosis in Rabbits: E. coli Infection and Dangerous Diarrhea

Colibacillosis is an intestinal infection linked to Escherichia coli (E. coli) bacteria. In rabbits, it is best known for causing severe diarrhea, dehydration, and weakness. According to the Merck Veterinary Manual, the disease is seen most often in very young kits around 1 to 2 weeks old and in recently weaned rabbits around 4 to 6 weeks old, when the digestive tract is especially vulnerable.

This condition can move fast. Young kits may develop severe yellow diarrhea and entire litters can be affected. In weaned rabbits, the illness may look similar to other serious intestinal diseases, with diarrhea, dehydration, and death occurring over several days if the rabbit does not respond to care.

Not every rabbit with soft stool has colibacillosis. Rabbits can also have diarrhea from parasites, diet problems, stress, unsafe antibiotics, or other infections. That is why a rabbit with true watery diarrhea needs prompt veterinary care rather than home treatment alone.

Colibacillosis happens when disease-causing E. coli bacteria multiply in the intestinal tract and trigger inflammation and diarrhea. Merck notes that healthy rabbits do not normally have E. coli in their digestive tracts, and the bacteria may multiply when a rabbit develops diarrhea for another reason. That means colibacillosis can be a primary problem or can complicate an already upset gut.

The rabbits at highest risk are neonatal kits and recently weaned rabbits. Weaning is a stressful transition, and stress can change appetite, gut movement, and the balance of normal intestinal bacteria. Crowding, poor sanitation, contaminated nesting areas, sudden diet changes, and low-fiber feeding can all make intestinal disease more likely.

Other illnesses can look similar or occur at the same time. Your vet may also consider coccidia, rotavirus, enterotoxemia, mucoid enteritis, dietary imbalance, or antibiotic-associated gut disruption. VCA also warns that some oral antibiotics, including oral penicillin and amoxicillin-type drugs, can disrupt normal rabbit gut bacteria and lead to dangerous diarrhea, so rabbits should never be medicated without veterinary guidance.

Diagnosis starts with a careful history and physical exam. Your vet will want to know your rabbit’s age, whether the rabbit is weaning, what the diet looks like, whether other rabbits are sick, and whether any medications were given recently. Because several rabbit diseases can cause diarrhea, diagnosis is usually about confirming E. coli while also ruling out other causes.

Merck states that your vet diagnoses colibacillosis by testing for E. coli. Depending on the case, that may include fecal testing, bacterial culture, or other laboratory methods chosen by the clinic or reference lab. Many rabbits with diarrhea also need checks for dehydration, body temperature changes, and gut pain. In sicker rabbits, your vet may recommend bloodwork to assess hydration, electrolytes, glucose, and organ function.

If your rabbit is very young, weak, or not eating, stabilization may happen at the same time as diagnostics. That can include warming, fluids, assisted feeding, and close monitoring while test results are pending. In rabbit medicine, supportive care often cannot wait for every result to come back.

Prevention focuses on sanitation, diet, and stress reduction. Merck notes that high-fiber diets appear to help prevent disease in weaned rabbits, so unlimited grass hay and a steady, appropriate rabbit diet matter. Avoid sudden food changes during weaning, and make any diet transition gradually with your vet’s guidance.

Keep nesting areas, litter areas, bowls, and housing clean and dry. After an outbreak, Merck recommends thorough disinfection and decontamination of the cage or hutch. Good hygiene lowers the bacterial load in the environment and may reduce spread between littermates or cage mates.

Medication safety is also part of prevention. VCA warns that some oral antibiotics can dangerously disrupt normal rabbit gut bacteria. Never give leftover antibiotics or over-the-counter medications unless your vet specifically tells you to. If you raise kits or have multiple rabbits, isolate any rabbit with diarrhea and arrange prompt veterinary care, because young rabbits can deteriorate quickly.