Biomedical subjects
Publications and source records attributed to F Riet-Correa.
Snakebite caused by Bothrops neuwiedi in sheep of southern Brazil is described. In a flock of 135 sheep, 22 were bitten and 11 died. Most cases occurred at the end of December and during January when the pastures were overgrazed due to severe drought. No more cases were observed after the end of January when abundant rainfall began. The main clinical signs were local edema followed by necrosis and sloughing of the skin.
A skin disease characterized by trauma-induced sloughing of haired skin, hooves, and horns is described in four calves from a herd of Murrah buffaloes (Bubalus bubalis) in Brazil. Affected calves were detected shortly after birth by the presence of lesions affecting the distal extremities, the scapular and gluteal regions, and the tip of the tail. On histologic evaluation of affected skin, the lesions were characterized by suprabasilar vesicles and acantholysis affecting the epidermis and outer root sheath of the hair follicle infundibulum. The basal cell layer was intact and appeared as a single layer of cuboidal cells attached to the dermis. Ultrastructurally, the region between the stratum basale and the lower stratum spinosum had widened intercellular spaces with loss of desmosomal attachments, which led to the suprabasilar separation. The disease appears to be inherited as an autosomal recessive trait.
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In southern Brazil, cattle are affected by a disease known locally as Lechiguana and characterized by large subcutaneous swellings. Eighteen cases were examined clinically; 17 of the cattle had a single swelling, and one had two swellings. In 14 of the 18 cases, the swellings were located over the scapula and adjacent regions. The subcutaneous masses reached maximum dimensions of 45 x 50 cm, with heights above the skin surface of 5-25 cm. Growth was rapid, often taking place in 15 to 60 days. Histologically, all lesions were focal proliferative fibrogranulomatous panniculitis and consisted of focal proliferation of fibrous tissue that was infiltrated by plasma cells, eosinophils, lymphocytes, and sometimes neutrophils. An eosinophilic lymphangitis was also present, which sometimes resulted in the destruction of the lymphatics and the formation of eosinophilic microabscesses. Small granulomas, sometimes containing radiating clubs, and Splendore-Hoeppli material were present in the regional lymph node. Pasteurella granulomatis was isolated from the subcutaneous masses of 14 of the 18 natural cases. All 11 of these cases recovered following treatment with 3 g of chloramphenicol daily for 5 days. Untreated animals died. Because the area of anatomic distribution is similar to that infested by Dermatobia hominis, we postulate that this insect may transmit the causative agent. In one steer, a subcutaneous injection of P. granulomatis caused a large subcutaneous swelling consisting of interlacing bundles of collagen infiltrated by neutrophils, eosinophils, and some lymphocytes. Microabscesses, but not lymphangitis and granulomas, were detected. In all 11 cattle inoculated either intramuscularly or subcutaneously with P. granulomatis, purulent abscesses were produced at the sites of the injection, and P. granulomatis was recovered from all lesions.
Congenital lymphedema is described in Hereford cattle. The disease was characterized by edema of the hind limbs, sometimes forelimbs, tail, and prepuce. Lymphatic system lesions were hypoplasia and aplasia of lymph vessels and prescapular, iliofemoral, and popliteal lymph nodes. Test matings demonstrated the transmission of the disease by an autosomal dominant trait with variable expressivity and incomplete penetrance.
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Three strains of a Pasteurella haemolytica-like bacterium were isolated from lesions of a progressive granuloma of cattle in southern Brazil. Their characteristics and their differentiation from P. haemolytica varieties and Actinobacillus lignieresii are described. The name "Pasteurella granulomatis" is proposed for this apparently new taxon.
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A bovine cerebellar disorder of recurrent seizures characterized by loss of equilibrium, extension of the head and thoracic limbs, opisthotonus, nystagmus and falling to the side or backwards is described from 16 farms in the Brazilian state of Rio Grande do Sul. The main pathologic features were vacuolation, degeneration and loss of Purkinje cells with axonal spheroids in the cerebellar granular layer and white matter. Electron microscopic study of Purkinje cells showed cytoplasmic membranous bodies, similar to those observed in human and animal gangliosidoses. Feeding trials in calves demonstrated that the disease is an intoxication caused by ingestion of Solanum fastigiatum var. fastigiatum. A hypothesis is proposed that the intoxication is an induced lysosomal storage disease, probably a gangliosidosis.
Equine pythiosis was studied in five animals from two farms located in a swampy region of southern Brazil (Rio Grande do Sul State). Granulomatous lesions exuding necrotic material and containing a central yellow and firm tissue core, the 'kunker', were observed on the top of the nose of one horse, on the abdomen of two horses and on the hind limbs of two other animals. Direct microscopic preparations, histopathological examination of lesion material, and macroscopic and microscopic characteristics of the isolates confirmed the diagnosis of pythiosis. Surgical intervention of the inflammatory processes, intravenous potassium iodide and topical application of copper sulphate were used without success.