Dealing with GI problems (Proceedings)


Dealing with GI problems (Proceedings)

Oct 01, 2008

Gastrointestinal problems are by far one of the most common problems that initiate a visit to the vet for the pet rabbit. These problems include anorexia, diarrhoea, caecal dysbiosis, gastrointestinal stasis, bloat and obstruction.

When a rabbit presents for any condition involving the GI tract, a thorough history can provide invaluable clues as to the problem at hand. One of the best examples of this is a history of anorexia. It is imperative to sort out from the history whether the rabbit is not eating because it has no interest in food at all versus having a great interest in food, but just not wanting to take food into its mouth. A complete lack of appetite is most commonly seen secondary to a severe physiological problem such as renal failure, whereas a scenario involving a rabbit showing a keen interest in food but not eating it is a classic presentation seen in rabbits with dental disease. It is very important for the clinician to emphasize to him/herself that the GI tract starts with the mouth. The most common dental disease responsible for anorexia in rabbits is misalignment of the molars and resultant overgrowth of the crowns of the teeth. Dysfunction of the upper arcades of cheek teeth most often involves spurs that grow into the buccal surface of the mouth, and dysfunction of the lower arcades of cheek teeth most often involve spurs impinging on the lingual surface. Although these statements are true over 90% of the time, there are cases that involve lingual spurs on the upper arcade of cheek teeth and buccal spurs on the lower arcade of cheek teeth.

A cursory exam on the awake patient with an otoscope will often reveal the offending molar spurs. However, sometimes a more thorough exam of the mouth while the patient is sedated is necessary. If dental disease is the reason for the anorexia, it is best addressed by sedating the rabbit and filing down the molar spurs as needed. This is most efficiently accomplished with a small hand rasp or careful use of a dental bur. Bone ronguers can be used to clip off prominent spurs. This instrument is appropriate because it is designed to cut sharply as opposed to cutting by compression. Any instrument that would not cut the teeth sharply or file the spurs down appropriately could potentially cause longitudinal microfractures in the teeth that would provide a pathway for bacteria to seed the jaw and create a jaw abscess. When proceeding with dental work on a rabbit in any manner, care should be taken to maintain or reproduce a normal occlusal angle when addressing molar malocclusion (Crossley, 1996).

Other dental disease that can preclude a rabbit from eating properly is malocclusion of the incisors. Rabbits are hypsodonts and thus, their teeth grow continuously. Since the only way to wear any substance down is to cut it or abrade it with another substance that is as hard or harder than it, it is essential that no matter what the rabbit chews on, it's teeth are properly occluded. It is only by normal mastication of the teeth while they are properly lined up that they wear one another down appropriately. The best way to address incisor malocclusion is to completely extract all of the incisors. If the owner will not concede to this procedure, it will be necessary to trim the incisors every 4-6 weeks. This is best done with a dremmel tool or dental bur. The owner should be strongly discouraged from trimming them with nail clippers, as they are likely to cause longitudinal fractures in the teeth.

Whenever dental disease of any form is present, it is imperative to take radiographs of the skull to fully evaluate the extent of the disease process. Ventrodorsal, as well as right and left oblique views are useful for evaluation of the dentition.

Signs that should incite the clinician to further investigate the teeth as the source of the problem, other than overt molar spurs seen on initial exam, are mucopurulent discharge around the base of any of the teeth, excessive salivation and horizontal bars across the incisor teeth. Mucopurulent discharge is usually secondary to a tooth root abscess. Excess salivation is seen when there is irritation of the tongue by a molar spur that may not be visible on initial exam. Horizontal bars across the incisors are commonly seen in rabbits that have dental disease secondary to a calcium or vitamin D deficiency (Harcourt-Brown, 1996).

True diarrhoea is most often seen in young rabbits and is usually secondary to parasitism. The most common parasites to cause diarrhoea is Eimeria species of coccidia. In managing this disease in rabbits it is important to consider environmental factors such as crowding and damp, dirty conditions that contribute to the spread of coccidosis. For the oocysts to become infective, they need to be exposed to oxygen for several days (Harcourt-Brown, 2002). Fastidious cleaning as well as medical management with trimethoprim/sulfamethoxazole at a dose of 30-40mg/kg PO q 12 hrs and supportive care are necessary to treat rabbits for this condition.

Owners will frequently report a history of diarrhoea to the clinician that is not truly diarrhoea, but rather caecal dysbiosis. By carefully questioning the owner as to whether or not there are normal, dry faecal pellets passed on the same day as the supposed diarrhoea, as well as the nature and odour of the "diarrhoea" can help the clinician distinguish between true diarrhoea and caecal dysbiosis. In a case of caecal dysbiosis, rabbits do tend to continue passing normal dry faecal pellets on the same day that they pass loose excrement. The end product that is passed as a result of caecal dysbiosis is usually thick, pasty and has a very pungent odour.