Feline histiocytic colitis. A case report with electron microscopy.

A 5-year-old cat with clinical colitis had histiocytic inflammation of colonic mucosa. Light and electron microscopy demonstrated bacilli, 0.7 x 3.0 micrometers, in various stages of degradation within macrophage cytoplasm. The disease is similar to histiocytic granulomatous bowel disease of other species. The cat responded to long-term treatment with antibiotics.