Cancer usually affects the intestine in one of two ways. Infiltrative intestinal disease, wherein cancer cells crowd out the normal functional cells of the intestine, interferes with digestion and absorption, causing weight loss and sometimes diarrhea. Cancer can also appear as single or multiple masses that mechanically block the intestine, causing colic and obstruction.
The most common infiltrative cancer in the horse is intestinal lymphosarcoma. The most common mass blocking the intestine is melanoma in gray horses. Beyond that, the only way to confirm a diagnosis of a particular type of cancer (and determine treatment and prognosis) is through biopsy.
In most cases, the affected intestine can only be accessed for biopsy using abdominal surgery, although in some cases, rectal biopsy can be helpful diagnostically. If abnormal intestine or a mass is visible via ultrasound, then ultrasound guided biopsy may be possible.
Other Diagnoses Considered
Prognosis & Relevant Factors
Generally, most cases of intestinal cancer have a poor prognosis. The treatment and prognosis depends on the specific diagnosis.
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