Veterinary Pathology

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.

Infusion of coagulase-negative cocci into normal udders of cows produced a moderate inflammatory reaction and persistent infection. Such quarters were as susceptible as normal controls to the subsequent infusion of coagulase-positive staphylococci. Cows already infected with coagulase-positive staphylococci were probably more susceptible to infusion of such organisms into their noninfected quarters than were normal cows. The lesions found following infusion of coagulase-negative cocci were similar but not as severe as those produced by coagulase-positive organisms. Ductal fibrosis and rosettes occurred with the latter organisms but not with the former coagulase-negative organisms. Atrophy which followed staphylococcal infection was an all or none effect with focal and lobular distribution.

Two steers were fed leaves of plants of the family Zamiaceae, one Bowenia serrulata and the other, Macrozamia lucida.

Degenerative lesions were demonstrated in the nerve fibres of the fasciculus gracilis and the dorsal spinocerebellar pathways.

Two naturally affected animals from an area where m. lucida was grazed were also examined, and in these, degenerative lesions of the fasciculus gracilis were found.

Two neurofibromas located at the base of the ventral paraflocculus of the cerebellum in an adult fin whale (Balaenoptera physalus) are described histologically. Both tumors were rich in collagenous fibers and related to nervous structures. There were remnants of atrophic myelinated nerve fibers, in loose arrangement, and ganglion cells within the neoplastic tissue.

Clinical and pathologic methods and attempts at transmission were employed to study so-called round heart disease of the domestic fowl. These studies indicate that the disease is noninfectious. The use of old litter in poultry houses contributed to the appearance of the disease but was not the sole etiologic factor. Zinc-plated feeders were not involved. The disease could not be reproduced by inoculation or feeding of affected material. Treatment of affected fowl with selenium dioxide was ineffective. Fatty and vacuolar degeneration of the myocardium and severe renal necrosis occurred. The disease is attributed to toxic injury. Its mechanism and the factors that condition it remain unknown.

Klinische und pathologische Untersuchungsmethoden sowie Übertragungsversuche wurden zur Untersuchung der sogenannten «Kugelherz» Krankheit vom Haushuhn verwendet.

The incidence, staining qualities, organ distribution, age of affected individuals, and disease conditions associated with avian amyloidosis occurring in a population of 1698 zoo birds were analysed. Amyloid disease occurs in older birds, predominantly affecting the liver, spleen, and adrenals. The staining qualities and morphology are very similar to mammalian amyloid. The disease occurs mainly in exotic or poorly adapted birds, apparently related to environmental factors rather than to any specific predisposing disease.

The incidence and contributing factors relating to amyloidosis in the family Anatidae were analysed by genus and species. There is a striking segregation of susceptibility by species, with exotic, poorly adapted or excessively aggressive birds being the most susceptible, and indigenous, well adapted non-aggressive or domestic types least susceptible. Other associations, such as chronic disease, are inconstant. Classifications such as primary and secondary amyloidosis do not apply to avian amyloidosis.

Spontaneous lipidosis of the central nervous system of two Yorkshire swine is reported. The presence of membranous cytoplasmic neuronal inclusions similar to those reported in Tay-Sach's disease in man was confirmed by electron microscopy.

Calcinosis circumscripta of the tongue is described in 6 large, young dogs. The lingual lesions are identical with calcinosis circumscripta as described in the literature and 10 subcutaneous lesions that we examined. It is suggested that the lingual and subcutaneous lesions are part of one disease process and that the former are more frequent than is indicated in the literature. Apocrine glands were not found in association with the lingual lesions or at comparable sites in the tongues of 6 unaffected dogs; it appears that their presence is not a prerequisite for the development of the lesion. Ten calcifying epitheliomas were also examined and evidence is presented which strongly suggests that this lesion be distinct from calcinosis circumscripta.

A carcinoid, metastatic in the liver, was found in an elephant in which kallikrein was demonstrated. This lends support to the hypothesis that kallikrein participates in the production of the carcinoid syndrome.

Multicentric, moderately malignant tumors of the nonchromaffin paraganglia at the site of the aortic body, at other sites of the cardiovascular system, and in the cranial mediastinal lymph nodes were discovered incidentally at autopsy of a 7-year-old female Siamese cat. Metastases were evident grossly in the myocardium, pericardium, and cranial mediastinal lymph nodes, and histologically as tumor emboli in the stromal vessels and in epicardial, myocardial, and pulmonary lymph channels.

Filtration studies indicate that the causative agent of feline infectious (fibrinous) peritonitis is less than 200 mμ in smallest dimension. Viral particles 94 mμ in diameter, within and budding into the endoplasmic reticulum of the mesothelial cells in areas of inflammation, were found by electron microscopy and may be the etiologic agent. No bacterium or mycoplasma was cultured from peritoneal exudate, nor identified in affected tissues.