2f:T4e0,

A 4-year-old Quarter Horse gelding was presented with a history of weight loss of 6 months duration, along with extensive ventral subcutaneous edema. Clinicopathologic findings included a markedly low serum total protein (2.9 g/dl) and a low packed cell volume (24%). The mucosal surface of the distal jejunum and entire ileum were carpeted with numerous polypoid, papillary, and glandular masses comprised of pseudostratified tall columnar cells and large numbers of interspersed goblet cells. Neoplastic change was diffuse throughout the mucosa of each mass, but abrupt demarcation occurred between neoplastic masses and adjacent mucosa. Immunohistochemical staining for protein of the p53 tumor suppressor gene revealed only occasional cytoplasmic reactivity within polyps and normal mucosa. Nuclear staining for papillomavirus antigens was not observed. Electron microscopic examination revealed features of well-differentiated intestinal epithelial cells, including apical tight junctions and microvilli, desmosomes, and the presence of numerous goblet cells. Microorganisms were not detected. Small intestinal polyposis should be considered as a rare differential diagnosis for protein-losing enteropathy in the horse.

30:T494,

Two weeks before dying of congestive heart failure, a juvenile black rhinoceros (Diceros bicornis minor) received a single low dose of doxorubicin as part of combination chemotherapy for acute lymphoblastic leukemia. Diffuse hemosiderosis was present at necropsy in a pattern indicative of dietary iron overload, but unique iron-positive degenerative lesions were found in isolated myocardiocytes. Serum analyses revealed hyperferremia, 87% transferrin saturation, and 5- to 10-fold elevations in ferritin concentration, reflecting markedly increased tissue iron stores. Since both toxic and therapeutic effects of anthracyclines are mediated by formation of reactive free radicals via iron-catalyzed reactions, these observations suggest that iron overload may have enhanced myocardial susceptibility to cardiotoxic effects of doxorubicin. Impairments in other myocardial antioxidant defenses, such as deficiencies in catalase and glutathione S-transferase that are known to exist in rhinoceros erythrocytes, may have been underlying factors contributing to an inherent sensitivity of rhinoceros tissues to oxidant-induced injury.

31:T46b,

An aged Saanen doe was euthanized following repeated severe hemorrhage from the vulva. Necropsy examination revealed mural thickening of tubular genitalia with firm, protruding intralumenal masses containing blood-filled cavitations, and effacement of normal cervical architecture. Histologically, uterine and cervical masses comprised a variably dense population of mildly pleomorphic spindle cells forming interlacing streams supported by variably dense collagenous stroma. Immunoperoxidase staining of neoplastic cells was positive for muscle-specific actin, supporting the diagnosis of low-grade leiomyosarcoma. Months later, the doe's twin was likewise euthanized due to persistent bleeding from the vulva associated with a large vulvar mass having histopathologic features similar to those of the previous case. The clinical, gross, and histologic findings are similar to five cases of caprine genital leiomyosarcoma identified in retrospectively analyzed case material. Analysis of caprine tumor accessions over 20 years demonstrated a significantly higher incidence of genital leiomyosarcoma within the Saanen breed.

32:T410,

A 2-year-old Basset Hound was admitted to the University of Florida Veterinary Medical Teaching Hospital with progressive spastic paraparesis. At necropsy, intradural extramedullary tumors produced areas of spinal cord swelling and softening in spinal cord segments T11–T12 and L4–L6. Histologic examination of the masses revealed sheets of polygonal blastemal cells, epithelial cells forming tubules and rosettes, and embryonal glomeruloid-like structures in the thoracic mass. Cells in the lumbar mass we