True diarrhoea in a rabbit: watery droppings, and why a young rabbit cannot wait

Quick answer

Most of what rabbit owners call diarrhoea is not diarrhoea. It is uneaten caecotrophs, the soft nutritional droppings a rabbit is supposed to eat directly, squashed onto the fur or the floor.

True diarrhoea is different, much rarer, and far more serious. In a rabbit under about four months old it is one of the fastest killers in the species, and the window between the first watery dropping and a dead rabbit can be under two days.

• The test that separates them: are there also normal hard round droppings? If yes, this is a caecotroph problem. If no droppings are formed at all, this is true diarrhoea.
• True diarrhoea in a rabbit of any age is a same-day emergency. In a young rabbit it is an immediate one.
• Do not withhold food and do not give human anti-diarrhoeal medicines. Both make a rabbit worse.
• The commonest triggers in young rabbits are a sudden diet change on arriving home, too much starch, and coccidia.
• In an adult, the first question a vet will ask is what antibiotics the rabbit has recently been given by mouth.

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A rabbit passing watery faeces with no formed droppings, especially one under six months old, needs a vet today.

The rabbit caecum holds a large, finely balanced microbial population. When it is disturbed, Clostridium species can overgrow and release toxin into the bloodstream. This is enterotoxaemia, and it can kill a young rabbit within a day. Cold ears, a hunched posture and weakness on top of the diarrhoea mean the process is already advanced.
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Decide in 60 seconds

The two droppings, and why the difference decides everything

Long-fibre hay is what keeps the whole system working. It is also the first thing to put back in front of a rabbit with gut trouble, never the first thing to take away.

What a rabbit's gut actually does.

A rabbit is a hindgut fermenter with a peculiar refinement. Material entering the colon is sorted: the large indigestible fibre particles are pushed straight through and out as the familiar round dry pellets, while the fine, nutrient-rich particles and fluid are moved backwards into the caecum to be fermented.

That sorting is done by muscular contractions in the proximal colon, and it depends on there being plenty of long fibre in the mix. Long fibre is not just nutrition. It is the mechanical signal that drives the whole system.

Caecotrophs.

The fermented caecal contents are expelled a few times a day as soft, dark, shiny, strongly smelling clusters coated in mucus, usually shaped like a small bunch of grapes. A healthy rabbit takes these directly from the anus and swallows them whole, normally when nobody is watching, and reingests the protein and B vitamins the bacteria have made.

You are not supposed to see caecotrophs. Finding them means they are not being eaten.

Why uneaten caecotrophs get mistaken for diarrhoea.

A squashed caecotroph on the floor or matted into the fur looks exactly like diarrhoea to an owner who has never seen an intact one. The clue is the company it keeps.

If normal round hard droppings are still being produced, the sorting mechanism is working and the gut is not in failure. The caecotrophs are being produced and not eaten, and the cause is usually a diet too rich in pellets, treats or sugar, or a rabbit that physically cannot reach its own rear because of obesity, arthritis, spinal pain or dental pain.

That is a real problem and it needs fixing, but it is a this-week problem rather than a tonight problem.

True diarrhoea.

In true diarrhoea nothing is formed. There are no round droppings on the floor, in the tray, or under the hay rack. What comes out is liquid or the texture of thin porridge, often with a rank smell, and the rabbit is usually unwell in itself: quiet, hunched, off its food, sometimes with cold ears.

This means the whole colonic sorting mechanism has failed. In a rabbit that is a systemic event, not a digestive inconvenience.

Why it kills so quickly

The caecum is a fermentation vessel, and its contents are alive.

A rabbit's caecum is proportionally enormous and holds a stable population of bacteria and protozoa. That population is what makes a rabbit able to live on grass. It is also fragile.

When the environment inside the caecum shifts, usually because fermentable starch or sugar has arrived where it should not, the fast-growing opportunists multiply. Clostridium species are among them, and some produce a toxin that is absorbed into the bloodstream.

That is enterotoxaemia. The rabbit is then dealing with a poison, not just a loose gut, and it can be dead within a day or two of the first sign.

A rabbit has almost no fluid reserve.

An animal weighing one or two kilograms loses a dangerous proportion of its body water very quickly through liquid faeces. Dehydration thickens the gut contents elsewhere, slows motility, and compounds the problem.

Cold is a late sign and a bad one.

Rabbits shed heat through their ears. A rabbit in circulatory failure shuts down the blood supply to the periphery, so the ears go cold. Cold ears in a rabbit with diarrhoea mean the animal is in shock and needs a vet immediately, not warming and watching.

Flystrike runs on a separate clock.

In warm weather, blowflies find soiled fur within hours and the larvae hatch fast. A rabbit can be simultaneously fighting enterotoxaemia and being eaten alive. This is why cleaning and drying the rear is part of the emergency response and not an afterthought.

Young rabbits: where true diarrhoea concentrates

Pellets weighed rather than poured. A young rabbit given free access to a concentrate is the commonest home-made cause of the problem this article is about.

Weaning is a biological cliff.

While a rabbit is suckling, the doe's milk contributes fatty acids that suppress bacterial overgrowth in the stomach and small intestine, and the gut environment is more acidic than it will be later. At weaning that protection disappears while the caecal population is still assembling itself.

The result is a window of several weeks where the rabbit's gut is genuinely vulnerable, and where anything that disturbs it has an outsized effect.

The move to a new home lands in exactly that window.

A young rabbit typically leaves the breeder or shop, travels, arrives in an unfamiliar place with unfamiliar smells and noises, and is offered a different pellet, a different hay, and often a bowl of fresh vegetables as a welcome.

Every one of those is a disturbance. Stacked together in one day, in an animal whose gut flora is not yet stable, they are a common route to enteritis.

The rule that prevents most of it is simple. For the first fortnight, change nothing. Feed the same pellet brand and the same hay the rabbit was already eating, obtain some from the seller if you can, and introduce your preferred food gradually afterwards.

Starch is the specific danger.

Bread, biscuit, breakfast cereal, crackers, cereal-based treat sticks and muesli-style rabbit mixes all deliver starch. A rabbit's small intestine cannot digest it fast enough, so it passes into the caecum, where it is exactly the substrate the harmful bacteria need.

Muesli mixes cause a second problem on top. The rabbit picks out the sweet flaked cereal pieces and leaves the fibrous pellet, so it eats a starch diet while the bag looks like it is being eaten normally.

Coccidia.

Eimeria are single-celled parasites that are extremely common in commercially bred rabbits. The intestinal forms cause diarrhoea, poor growth, dehydration and death in young rabbits. A separate species attacks the liver and damages it silently.

Rabbits are infected by swallowing oocysts passed in droppings. The important practical detail is that a freshly passed oocyst is not yet infectious. It has to sit in the environment for a day or more to mature. Cleaning the tray and any soiled bedding daily therefore breaks the cycle by mechanical means alone, which is why coccidiosis explodes in overcrowded or infrequently cleaned housing and in warm damp weather.

Mucoid enteropathy.

A distinct and dangerous syndrome, mostly in young rabbits, in which large amounts of gelatinous mucus are passed, the gut becomes impacted, and the rabbit deteriorates rapidly. Any rabbit passing clear or cloudy jelly needs to be seen the same day.

Rotavirus, E. coli and mixed infections.

Several infectious agents cause enteritis in young rabbits and they frequently occur together with diet and stress factors. This is one reason a faecal sample is worth taking to the appointment.

Adults: a different and shorter list

True diarrhoea in an adult rabbit is uncommon, and when it happens the causes are more specific.

Antibiotics given by mouth.

This is the first thing to consider. Several antibiotic classes act mainly against Gram-positive bacteria, which is most of a rabbit's normal caecal population. Given by mouth they can clear the way for Clostridium and cause fatal enterotoxaemia.

A vet experienced with rabbits knows which drugs are safe by which route, and will avoid the dangerous ones or use them only by injection. The risk arises when a rabbit is prescribed a general-purpose oral antibiotic by someone who does not routinely see rabbits, or when an owner uses medication left over from another animal.

If your rabbit develops diarrhoea while on an oral antibiotic, phone the prescribing practice before the next dose.

A sudden flood of rich food.

A rabbit that gets into a bag of pellets, a bowl of fruit, or a sudden large quantity of lush spring grass it is not used to can tip its caecum over.

Toxins and plants.

Less common, but ornamental plants, treated grass and some human foods can produce it.

Underlying disease.

Liver disease, kidney disease and tumours occasionally present this way in older rabbits, usually with weight loss over the preceding weeks.

What to do in the first hour

Why not to withhold food.

Fasting is standard advice for a dog with an upset stomach and it is dangerous in a rabbit. Rabbits cannot vomit, so there is no reason to empty the stomach, and a gut with nothing moving through it stops. Even a very sick rabbit should have hay available, and a vet will usually start syringe-feeding a fibre formula rather than resting the gut.

What the vet will do and what to bring

Take with you:

• The fresh sample and the photographs
• The rabbit's age, and where and when you got it
• Exactly what it eats, including brand names and any treats, and what changed and when
• Any medication given in the last month, by anyone, including anything left over from another pet
• Whether other rabbits in the house or from the same source are affected
• A recent weight if you have one

Expect a weight, a temperature, an assessment of hydration, abdominal palpation for gas, fluid or a firm mass, and listening for gut sounds. A subnormal temperature changes the plan and is treated as an emergency in itself.

Faecal examination looks for coccidial oocysts and for the appearance of the bacterial population under the microscope, and cultures or DNA tests are used where a specific organism matters. Blood tests assess hydration, organ function and blood glucose, which vets use in rabbits as one of several pointers when deciding between a gut that has slowed and a gut that is obstructed. Radiographs show gas patterns and can identify an obstruction.

Treatment is built around fluids, warmth, pain relief, and getting fibre back into the gut, plus a specific treatment for coccidia if it is found. Antibiotics are used only where they are indicated and only from the classes that are safe in rabbits, because the wrong choice makes the disease worse.

Availability of the anti-coccidial medicines differs a great deal between countries, so the exact product your vet reaches for will vary.

Preventing it

Greens are good food and a bad surprise. Introduced one at a time into a settled rabbit that is already eating hay well, they are safe; delivered as a bowlful on day one in a new home, they are a common trigger.

Change nothing for the first two weeks.

Same pellet, same hay, same water source. Get a bag from the seller if you can. Every change you want to make can be made slowly afterwards, and there is nothing to be gained by making it on day one.

Hay first, unlimited, from the beginning.

Long fibre is what drives the sorting mechanism. A rabbit eating plenty of hay is far more robust to everything else.

Weigh the pellets.

A measured daily ration, not a bowl that gets topped up. Free access to concentrate is a reliable way to produce a rabbit that eats little hay and has a caecum full of starch.

Introduce greens one at a time.

A small amount of one new plant, then several days of watching the droppings before adding another. This is slower than most owners expect and it is the whole protocol.

Clean daily.

Litter tray and any soiled bedding, every day. This is the mechanical control for coccidia and it costs nothing.

Quarantine new arrivals.

Keep a new rabbit separate from resident rabbits until it has settled and its droppings are normal, and handle the resident rabbits first.

Do not feed starch, ever.

No bread, cereal, biscuit, crackers, cereal treat sticks or muesli mixes, at any age.

What never to do

Do not wait overnight.

Young rabbits with true diarrhoea die overnight. This is not an exaggeration and it is the single reason this article exists.

Do not treat with yoghurt or human probiotics.

Rabbit caecal flora is not the same as human gut flora, milk products are not appropriate for a rabbit, and a sugary drink adds fermentable carbohydrate to the exact place that already has too much.

Do not use another animal's antibiotics.

The classes that are safe in a dog can be fatal in a rabbit by mouth.

Do not bathe a soiled rabbit in a sink of water.

Full immersion terrifies rabbits, causes struggling that can fracture a spine, and leaves a wet coat that will not dry. Clean the soiled area only, and dry it thoroughly.

Do not assume a soft dropping is nothing because the rabbit seems bright.

Rabbits hide illness until late. Bright and eating is not the same as well.

An empty bowl is only good news if the hay is also going down and the droppings are normal. Judge appetite by output, not by what has disappeared from the dish.

When to get help

Immediately, today:

• Watery or unformed faeces with no normal droppings present
• Any diarrhoea in a rabbit under six months old
• Diarrhoea in a rabbit currently taking an oral antibiotic
• Clear or cloudy jelly passed from the rear
• A rabbit that has stopped eating, is hunched, or is grinding its teeth
• Cold ears, weakness or collapse
• Maggots or fly eggs found in soiled fur

Within the week:

• Soft caecotrophs stuck to the fur, with normal hard droppings still being produced
• A gradual change in dropping size or number
• An older rabbit that has begun leaving caecotrophs after years of not doing so, which is usually about pain or mobility rather than diet

Register with a rabbit-experienced practice before you need one, and find out now what happens out of hours. A rabbit with true diarrhoea has hours, and the search for someone who will see a rabbit at midnight is not one you want to start that night.