Differential diagnosis for megacolon in rabbits

Veterinary textbook related to internal medicine mention dysautomia with the following terms:

· constipation,

· colonic weakness,

· neuromuscular weakness/disease,

· megacolon,

In case of traumatic origin:

· bilateral pelvic nerve damage.

while rabbit owner tend to call it “cow-pile syndrome...

If the problem is chronic in time, nerve damage may be ruled out and other causes should be looked for, among others:

Viral causes

Inflammation due to the presence of Cytomegaloviruses, Coronaviruses

Bacterial causes

Lack of proper bacterial flora

Parasitic causes	Coccidiosis
	Giardiasis
	Presence of the flagellate Trypanosoma cruzi (this parasite was experimentally inoculated in rabbits and found to cause severe damage on heart and intestine, leading to megacolon),
	Parasitic roundworms or tapeworm. Their presence has been linked to some bad cases of cecal impaction, accompanied by stasis, terrible pain and gas formation, this independently from the type of worm: pinworm or tapeworm. Treatment of rabbit pinworm can be done by administration of benzimidazoles, more specifically fenbendazole or thiabendazole. Piperazine is reported efficient too, while ivermectin does not affect the Passalurus worm. Treatment of tapeworm is done with praziquantel.

Genetic causes	The megacolon syndrome being more frequent in albino rabbits (or Spot breeds, see Searle AG. Comparative genetics of albinism. Ophthalmic Paediatr Genet. 1990, 1(3):159-64 for a general review, including rabbits; Bodeker D, Turck O, Loven E, Wieberneit D, Wegner W. Pathophysiological and functional aspects of the megacolon-syndrome of homozygous spotted rabbits.Zentralbl Veterinarmed A. 1995 Nov;42(9):549-59.
	Muscular disturbance of the colonic smooth muscle,
	Nerve injury or damage
	Presence of tumors, polyps

Mechanical	Stenosis
	Muscular disturbance of the colonic smooth muscle,
	Nerve injury or damage
	Presence of tumors, polyps

Neurological causes

Nerve injury or damage

Metabolic causes

Inflammation due to the presence of Cytomegaloviruses, Coronaviruses

Pharmacological causes

Overmedication

Hormonal causes

Hypothyroidism

Environmental causes

Behavior

Diagnosis tools include X-ray, barium test, ultrasound, eventually a neurological examination, serum profile probably will indicate colonic weakness in rabbits, as in other animals. If true megacolon is diagnosed, the rabbit shows a constant (and not chronic) leakage of mucus/watery stuff via the anus and hyponatremia (blood sodium level under average).

For reference blood biochemistry values in rabbits: click here.

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