Acute gastrointestinal disturbances in rabbits

(Reproduced on Rabbit Information Service Website with permission of author/s)

Owen Davies BVSc MRCVS and Linda Dykes MBBS (Hons)

Introduction

The fancy is buzzing with tales of some devastating new disease which is killing thousands of rabbits. In fact there's little evidence to suggest that any new disease has appeared. It's much more likely that some familiar old problems have made a resurgence.

The rabbit digestive system

The rabbit digestive system has evolved to utilise the diet of low quality, high fibre plants eaten by wild rabbits. This diet doesn't provide sufficient nutrients in itself. Instead, nutrients are manufactured by bacteria within the caecum who are able to utilise material that the rabbit cannot digest itself. Caecotrophs ("night pellets") are then re-ingested by the rabbit.

Healthy rabbit guts contain the right type of food (high fibre, moderate protein, low starch) constantly moving through the system, and a healthy bacterial population in the large bowel. If any or all of these things change then rabbits can die within hours. Any or all of the following may occur with or without diarrhoea.

- fluid shifts causing dehydration and shock
- toxins released inside the gut
- pain
- disturbance of bacterial flora.
- electrolyte (salt) disturbances

Common causes of GI disease in rabbits

Listed here are some common causes of GI disturbances. Most of these diseases are indistinguishable without laboratory testing, and young rabbits (especially around weaning) are always most susceptible. We have concentrated on diseases found in fancy rabbits over the past few years that have been treated by one of the authors.

Coccidiosis

Two forms of coccidiosis affect rabbits - hepatic and intestinal. The intestinal form that can cause acute diarrhoeal illness as well chronic problems; the hepatic form can cause a bloat type picture. Coccidiosis is diagnosed by examining faeces or large bowel contents under a microscope. Some strains of coccidosis are more dangerous than others.

Pathogenic Staphyloccocus

Some cases of "pet shop scours" have been caused by this bacteria, which has also affected fancier's rabbit. It often causes "bloat" without diarrhoea. At post mortem, the contents of the caecum tend to be impacted but stomach and small bowel contents liquid. Staphylococcus bacteria can be cultured from free fluid in the peritoneum (abdominal cavity), and sometimes associated liver abscesses.

Mucoid enteropathies

It's been known for many years that young rabbits develop a severe illness characterised by abdominal pain (alert owners notice the posture and teeth grinding of a rabbit in pain); loss of appetite; and production of thick jelly like material from the back passage. Problems may occur around weaning; with change of homes or diet; or even the stress of travelling to shows. Lack of dietary fibre is strongly implicated in many cases of mucoid enteropathy.

But that's not the whole story. Vets have found that rabbits with mucoid enteropathy have virtually identical pathological changes to horses with the dreaded disease Grass Sickness. The gut - like all body systems - is controlled by the autonomic nervous system. It's this network of nerves that seems to go wrong in mucoid enteropathies - the intestines come to a standstill and secrete excess mucus. Some rabbits develop signs suggesting disruption to other parts of the autonomic nervous system, such as a relatively slow heart rate and urinary incontinence.

Acute attacks are usually fatal in rabbits and horses. Occasionally survivors are reported, but only after very intensive supportive care. The chronic variant of the disease carries a better prognosis.

Grass sickness is a major concern of the equine industry, and research into it may well unravel the mysteries of mucoid enteropathies in rabbits. However until a cause has been identified then no specific treatment is available.

Antibiotic associated diarrhoea

1. Mild

Many antibiotics cause some alteration in the bacterial population of the gut, which can cause loose stools. This is usually mild.

2. Severe

Some antibiotics cause severe and often fatal diarrhoea in rabbits, because they allow a toxin-producing strain of Clostridium bacteria to multiply preferentially within the gut. This is why antibiotics have to be used carefully in rabbits - never, ever use antibiotics left over from some other animal or something prescribed for someone else's rabbits.

Viruses

Diarrhoeal illnesses can be caused by rotaviruses, but it's not known how common they are in British show rabbits.

Other bacteria

Other pathogenic bacteria (different strains of E.coli or Clostridia; Campylobacter; Salmonella; Pseudomonas) can cause problems. Laboratory testing is the only way to identify which of these bacteria may be present.

Other parasites

Cryptosporidium can affect rabbits, as well guinea pigs, humans and calves. It can be spread in many ways, including in water. There have been some well publicised outbreaks in UK domestic water supplies in the past few years - did any fanciers living in these areas have problems with their rabbits?

Two pathogens?

Some of these pathogens are opportunistic and may co-exist. For example, rabbits suffering from mucoid enteropathies are often also affected by Coccidia, Clostridium perfringens, and Clostridium spiroforme. And there's nothing to stop a rabbitry developing a second problem after the first has been cleared up.

GI stasis

Sometimes rabbit guts stop moving, usually because of an underlying illness such as dental pain or hidden infection. The result - an anorexic, poorly rabbit, passing little or no faeces, and with abdominal discomfort - is just like the early stages of many gut diseases. If only one rabbit is affected, then GI stasis may be the problem. The underlying cause must be treated treated as well as supportive therapy for the stasis itself.

Identifying the cause

Identical sounding symptoms may be due to completely different reasons, so you must identify the problem affecting your rabbits rather than assuming it's the same as Joe Bloggs down the road! You'll need to formulate a plan with your vet.

A full post mortem includes specialist tests such as bacteriology and histology - looking at affected tissues at a microscopic level. The rabbit's body (or tissues samples taken by your own vet) will need to be sent away, and must be fresh - the same day if possible. If there is any delay, then putting the body in the fridge destroys less evidence than freezing it. A full PM costs around 100, but is most likely to provide a diagnosis which might save the rest of your rabbits.

A limited post mortem - an inspection of the rabbit's internal organs - can be performed by your own vet. Your vet needs to be experienced at rabbit autopsies, as appearances change very rapidly after death, especially in the GI tract. The cost will be in the region of 15 - 20. If the body has been frozen then a "look and see" PM is probably all that can give useful information.

Faecal microscopy is simple to perform and you can use samples from a live rabbit! It's main role is to diagnose or exclude coccidiosis, but it might also pick up contributory problems such as worm infestation.

Treating affected rabbits

Once an rabbit has run into problems a decision must be made whether to treat or euthanase. An animal lying unresponsive in a pool of liquid diarrhoea, or breathing with difficulty due to a bloated abdomen, is unlikely to recover. Most fanciers would immediately destroy such animals. Treatment may be attempted in a companion rabbit, but even with the best intensive care, the prognosis is extremely guarded.

Less severely affected rabbits may recover, but adequate supportive therapy will be required as well as specific treatment if the cause is known. Some rabbits do return to full breeding or show condition after recovery from GI disturbances, but owners must be willing to devote time and money into treating affected rabbits. Otherwise it is probably kinder to cull at the first sign of trouble.

General supportive measures
Isolate sick rabbits

Keep them warm and quiet. Attend to sick rabbits after healthy ones, and wash your hands after nursing duties. Bring very ill animals indoors for nursing and heat.

Fluids

The key to treating any critically ill rabbit is warmed fluids by a suitable route. Rabbits need 80-100ml of fluid per kg every 24 hours, plus replacement of losses in diarrhoea/mucus, plus catching up on losses that have already occurred. Fluid losses from the gut contain salts (electrolytes) as well as water. Both need to be replaced, so plain water may not be sufficient.

Orally

Giving fluids by mouth will only help mildly affected rabbits. If the guts are at a standstill or the rabbit is shocked, the fluid will not be absorbed. Electrolyte replacement fluids (e.g. Lectade) can be obtained from the vet for oral therapy. It can be very difficult to give the quantity of fluid required by forced syringing into a reluctant rabbit!

Subcutaneously

Probably the most popular way to give fluids to moderate and severely ill rabbits. Fluid is injected under the loose skin of the scruff/shoulders, from where it can be absorbed into the bloodstream. Ask your vet to teach you how to give subcutaneous injections. Hartmann's (lactated Ringer's) solution or Normal Saline are both suitable. These come in a flexible bag, which can be microwaved to blood temperature. Desperately sick rabbits don't reliably absorb subcut fluids, because blood supply to the skin is reduced in shock.

Intraperitoneal

Fluid can be injected into the abdominal cavity. It's trickier than subcut, but better absorbed. Some vets are willing to teach competent owners - others avoid this route themselves!

Intravenous and intraosseous fluids may be given to severely ill rabbits as in-patients. Realistically, only used for companion rabbits.

Pain relief

Rabbits that are in pain will not eat. Analgesia is a vital part of nursing a sick rabbit, and a rabbit may be in pain without the classic teeth-grinding. Clues include abnormal posture; straining; lying with tummy pressed to the floor; or reluctance to move. Ask the vet to prescribe suitable pain killers. Rabbits with gassy, bloated tummies may benefit from simethicone (Infa-Col), an over the counter medicine for babies with colic which breaks down gas bubbles. It's chemically inert, has no interactions, and certainly won't do any harm.

Probiotics

In any sick rabbit - especially one with acute gastro-intestinal disturbance - the gut flora is at risk if not already disrupted. Giving a probiotic ("friendly bacteria") may help crowd out pathogenic bacteria. The problem is how to get live bacteria through the highly acidic environment of the stomach. The best probiotic is caecal pellets from a healthy rabbit, which have a mucus coating to withstand stomach acid. However some commercial preparations such as Avi-pro claim withstand the acid and deliver beneficial live bacteria to the intestines.

Laxatives

There may be a place for liquid paraffin (given orally) in rabbits with bloated abdomens and clinically impacted bowels. Gentle enemas have also been reported to help rabbits with obstructions at the far end of the large bowel. Your vet will advise.

Pro-motility agents

Drugs such as metoclopramide and cisapride, which encourage the gut to keep moving can be useful in cases where the guts have stopped moving. However they must not be used where the gut is completely blocked. Determining this may need an X-ray.

Tempting foods

Always provide fresh, top quality hay. Some plants - such as raspberry and blackberry - have long been used for scouring rabbits, but the problem is often persuading the rabbit to eat anything at all. Force feeding small amounts of baby cereal (Milupa) or mushed-up rabbit pellets with a little glucose, may be needed until the rabbit starts to eat by itself. You'll need to offer all sorts of tempting foods (e.g. herbs; freshly picked grass; Yeasac or products containing it)

Specific treatment

Coccidiosis can be treated with sulpha-based drugs. Some vets are also experimenting with a new product designed to treat coccidiosis in sheep. Bacterial diseases may respond to suitable antibiotics, but only if you have a proven diagnosis - otherwise you may make things worse. Severe antibiotic associated colitis may be helped by cholestyramine, a drug used in humans to bind cholestrol, as it also binds the Clostridium toxin that poisons the gut.

Prevention

The best way to avoid these diseases (or contain problems that have started), is by careful husbandry and obsessive hygiene. This will go a very long way to preventing diseases associated with poor hygiene and overcrowding (such as coccidiosis). A shed full of rabbits in the pink of condition is inherently less susceptible to stress related problems.

Overcrowding causes problems due to stressed animals and difficulty maintaining standards of hygiene. Avoid mixing litters at weaning and don't breed unless you have hutch space available.

Wean youngsters as late as possible, to minimise stress and ensure that gut flora is well established - babies can stay with mum until they are10 weeks old, so long as the hutch doesn't get overcrowded. Always remove mum from the litter rather than the other way round.

Hay is absolutely vital - all rabbits at any age need access to unlimited, good quality hay. Lack of fibre is a prime cause of many rabbit digestive problems. If good hay is not available, supply another source of roughage such as barley straw or Redigrass.

Hygiene is vitally important. Pathogens build up, especially in untreated wood, and some of the diseases we have discussed produce tough spores or oocysts that are very resistant to disinfectation.

Frequent cleaning out (2-3 x per week) reduces coccidiosis loads and is advisable for any rabbitry experiencing disease problems. Many fanciers diligently disinfect their hutches weekly, but the methods and products used are often ineffective. Many products are inactivated by organic matter, and will only work on surfaces that have already been thoroughly cleaned. Spraying disinfectant onto a roughly swept out hutch that is still damp in the dirty corner is absolutely useless. Talk to your vet about choice of disinfectant. For example, Dettol and Trigene are both rapidly inactivated by very tiny amounts of faeces. Virkon is more active in the presence of organic material, but won't touch coccidiosis, which in turn requires a phenol-based (and therefore more toxic) product such as Jeyes fluid.

Much more effective is rotating hutches to allow them to fully dry out between occupants, and taking hutches out into sunlight where UV light can kill organisms.

Diet is very important. Many fanciers mix food using several constituents, often pellets plus oats plus a rabbit mix. This can easily lead to an unbalanced ration which is made worse when rabbits are not fed hay. It is much better to stick to one quality branded feed, properly designed and balanced, with hay ad lib. If you want to feed greens then introduce them gradually and feed them regularly.

Anti-coccidiostats (ACS) are drugs included in some rabbit foods that suppress (not cure) intestinal coccidiosis, and don't work on hepatic cocci at all. Overwhelming coccidiosis infection can develop if animals are changed onto non-ACS food, because the coccidiosis can then multiply uncontrolled. Fanciers using ACS pellets as part of a home-mixed ration will be feeding ineffective concentrations anyway. ACS foods are fine as the sole diet of commercial rabbits with a limited lifespan, but for fancy and pet rabbits they cause more problems than they solve and are not recommended. Instead of continuous low-dose ACS drugs in the feed, there may be benefit from using a more potent anti-coccidial drug two or more times a year. Discuss with your vet.

Clostridial vaccines. If your stud has a proven clostridial disease problem, then theoretically, sheep clostridial vaccines may provide some cross immunity. Giving sheep vaccine to rabbits is completely unproven and unlicensed, but in the face of severe problems it may be worth chatting to your vet.


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