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Fifty male F344 rats were given diets containing 500 mg/kg P-chloroaniline. Controls received diets without the chemical. Eighteen of the dosed rats developed proliferative lesions of the spleen. Lesions included parenchymal fibrosis and fatty infiltration, well and poorly differentiated fibrosarcomas, osteosarcomas and hemangiosarcomas. All dosed rats had focal and diffuse fibrosis and papillary hyperplasia of the splenic capsule.

An 8-month-old female calf had a coccidian of the genus Cryptosporidium. This is the first report of cryptosporidial infection in cattle. The clinical syndrome was characterized by diarrhea, debilitation, and a chronic course. Gross lesions related to the infection were mild; however, histopathologic findings in the small intestine were generally characterized by villous atrophy and the presence of various developmental forms of Cryptosporidia in the microvillous border of the epithelium. The existence of signs and lesions very similar to those reported in the turkey and guinea pig suggests that disease in the calf might have been caused by cryptosporidial infection.

Pulmonary granulomas were incidental findings at necropsy in 18 dogs, mainly of the brachycephalic breeds. These lesions were multifocal along smaller bronchi and the subpleural tissue at the margins of lobes. The granulomatous reaction contained numerous periodic acid-Schiff (PAS)-positive bodies that histochemically had reactions suggestive of a calcium-lipid-mucopolysaccharide complex. Although the cause is not clear, the location and distribution are suggestive of an inhalation or aspiration pneumonia. The shortened muzzle of brachycephalic breeds, particularly when there is concurrent upper respiratory disease, may predispose them to these bodies.

Acanthamoeba infection occurred in a 4-year-old military working dog (German shepherd). The disease was manifested by multifocal necrohemorrhagic foci in the heart, lungs, liver, and pancreas. Numerous organisms morphologically compatible with Acanthamoeba sp. were seen in the lesions. The infection may have been caused by local invasion of a wound and hematogenous spread, via the respiratory tract, by inhalation of the organisms, or by direct extension of an inapparent nasal infection.

Myelolipomas of the liver were reported in 7 captive wild Felidae, 4 of which also had microscopic myelolipomatous lesions in the spleen. Out of approximately 25,000 animals examined, these were the only myelolipomas of the liver to be found. Previously unreported in either man or animals, myelolipomas of the liver are comparable to those in the human adrenal.

A case of Hartmannella sp. (Acanthamoeba) infection in a 1 1/2-year-old Holstein bull is reported. The disease was manifested by multifocal necrohemorrhagic nodules throughout the lung. Diagnosis was made on a morphologic basis by observing typical organisms within these nodules. The suggested mode of entry of the organism was via inhalation of the organisms or by direct extension from an inapparent nasal infection.

The clinical and pathologic features of 26 neoplasms derived from gonadal stroma of hovine species were analyzed. Two types were identified-1 a typical granulosa tumor, the other having a Sertoli pattern. The 13 granulosa tumors occurred in adult animals, 2 of which exhibited nymphomania. Nine of the 13 had metastasized by the time of discovery. The Sertoli type of tumor also occurred in adult animals. Estrinizing effects were more common in these, as the endometrium had varying degrees of hyperplasia or thickening in 7 instances, and 1 animal had persistent estrus. None had spread beyond the ovary. The Sertoli type was thought to be more closely related to granulosa tumors than arrhenoblastomas because it was associated with estrinizing rather than virilizing effect, all of them lacked Leydig cells, some had overlapping microscopic patterns with granulosa tumors. and a Sertoli arrangement could be identified that was similar to areas in early graafian follicles and atretic follicles. They merit separation from granulosa tumors because of their distinctive histological pattern and because of their much more benign clinical behavior.

This is the first report of the presence of organisms of Prototheca sp. in the tissue of cattle. Three cases are reported, and in each the organisms histologically resembled Prototheca segbwena. They provoked an extensive granulomatous lymphadenitis characterized by large accumulations of epithelioid cells. In 1 case, the organism caused multiple foci of proliferative peritonitis characterized by marked proliferation of mesothelial cells.

This is the first report of a spontaneous case of protothecosis in the dog, an infection with organisms of the algal genus Prototheca.Clinically the animal had chronic bilateral iritis accompanied by glaucoma of one eye and hypotony of the other, chronic nephritis, arthritis, and bloody diarrhea. Lesions containing the algae occurred in myocardium, liver, kidneys, para-adrenal connective tissue, brain, and eyes.

Mast-cell neoplasms may originate in skin or internal viscera of cats. Mast-cell or basophilic myelocytic leukemia may accompany disseminated mastocytosis. Ages of affected cats range from 4 to 16 years with a median age of 10 years. There is no definite predilection as to sex or breed, Neoplastic mast cells vary in degree of differentiation.