Differential diagnosis for megacolon in rabbits

also called “cow-pile syndrome”

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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.

If the problem becomes chronic with 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 intestinal or cecal impaction, accompanied by stasis, severe pain and gas formation, this independently from the type of worm: pinworm or tapeworm. Treatment of pinworms is done by administration of benzimidazoles, more specifically fenbendazole or thiabendazole. Piperazine is reported efficient too, while ivermectin does not affect the Passalurus roundworm. Treatment of tapeworm is done with praziquantel.

Genetic causes	Megacolon, affecting homozygotous checkered rabbits: Pathophysiological and functional aspects of the megacolon-syndrome of homozygous spotted rabbits, by Bödeker et al.
	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

The following tools are used to diagnose the condition: X-ray, barium test, ultrasound, and eventually, a neurological examination. A serum profile will probably indicate colonic weakness in rabbits, as in other animals. If the diagnosis of megacolon is confirmed, the rabbit will exhibit a persistent (and not chronic) leakage of mucus and watery substances through the anus, accompanied by hyponatremia (a decrease in blood sodium levels below the average range).

For reference blood biochemistry values in rabbits: click here.

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