Ovine leptospirosis in Brazil

Leptospirosis is a zoonosis distributed worldwide, endemic mainly in humid subtropical and tropical countries, with epidemic potential. It affects a range of both wild and domestic animals, including sheep, which transport leptospires in their urine and, therefore, can infect other animals and humans who deal with them. Therefore, leptospirosis is characterized as an occupational zoonosis. In individual herds leptospirosis can cause severe economic loss due to miscarriages and outbreaks of mastitis with a significant reduction of milk production. The disease is caused by Leptospira interrogans, which was reclassified into 13 pathogenic species, and distributed into more than 260 serovars classified into 23 serogroups. The clinical signs of infection may vary depending on the serovar and host. In maintenance hosts, antibody production is generally low; there are relatively mild signs of the disease, and a prolonged carrier state with organisms in the kidneys. In incidental hosts, the disease may be more severe, with high titers of circulating antibodies and a very short or nonexistent renal carrier state. In general, young animals with renal and hepatic failure have more serious infections than adults. Several diseases may produce symptoms similar to those of leptospirosis, so that laboratory confirmation, through microscopic agglutination test, for example, is required. The effectiveness of treatment depends on early diagnosis and appropriate therapy, depending on clinical features, since leptospirosis can develop into chronic liver disease and nephropathy, progressing towards death. Improvements in habitation and sanitary conditions, rodent control, vaccination, isolation and treatment of affected animals are the main measures for the control of leptospirosis.(AU)

Biochemical and biological evaluation of gyroxin isolated from Crotalus durissus terrificus venom

Gyroxin, a thrombin-like enzyme isolated from Crotalus durissus terrificus venom and capable of converting fibrinogen into fibrin, presents coagulant and neurotoxic activities. The aim of the present study was to evaluate such coagulant and toxic properties. Gyroxin was isolated using only two chromatographic steps - namely gel filtration (Sephadex G-75) and affinity (Benzamidine Sepharose 6B) - resulting in a sample of high purity, as evaluated by RP-HPLC C2/C18 and electrophoretic analysis that showed a molecular mass of 30 kDa. Gyroxin hydrolyzed specific chromogenic substrates, which caused it to be classified as a serine proteinase and thrombin-like enzyme. It was stable from pH 5.5 to 8.5 and inhibited by Mn²+, Cu²+, PMSF and benzamidine. Human plasma coagulation was more efficient at pH 6.0. An in vivo toxicity test showed that only behavioral alterations occurred, with no barrel rotation. Gyroxin was not able to block neuromuscular contraction in vitro, which suggests that its action, at the studied concentrations, has no effect on the peripheral nervous system.(AU)

Envenomation caused by Latrodectus geometricus in São Paulo state, Brazil: a case report

Widow spiders (Latrodectus spp.), also known as "black widows", have a worldwide distribution and can cause latrodectism. To the best of our knowledge, in Brazil, only one case of Latrodectus geometricus (Koch, 1841) envenomation in a human has been reported. The aim of the present report is to describe a spider bite caused by Latrodectus geometricus in a patient who lives in Paranapanema, São Paulo state, Brazil.(AU)

Young ovine death during hyperimmunization: crotalic envenomation or copper toxicosis?

The unfavorable evolution of a young ovine during hyperimmunization process with Crotalus durissus terrificus venom was investigated in order to differentiate its origin between ophidic envenomation and copper toxicosis. Clinical, laboratory, necroscopic and histological exams as well as evaluation and measurement of heavy metals (copper) in the kidneys and in the liver were carried out. Blood counts revealed anemia and serological tests showed high levels of blood urea nitrogen, creatinine, aspartate aminotransferase, creatine phosphokinase, total bilirubin and indirect bilirubin; which indicates liver, kidney and skeletal muscle damages. At necropsy, the animal presented hepatopathy and nephropathy. Histological examination revealed renal and hepatic features that may imply copper intoxication. Copper levels were 237.8 µg/g in the liver and 51.2 µg/g in the kidneys. Although the amount of metal found in both organs was below the level that can cause death, according to the literature, anatomopathological signs were suggestive of copper intoxication. Therefore, the hypothesis of metal toxicosis during the hyperimmunization process became more consistent than the crotalic envenomation one.(AU)

Management of venomous snakebites in dogs and cats in Brazil

Snake envenoming is a major problem both to veterinary and human medicine in tropical countries due to high incidence, severity, and sequelae. In Brazil, most envenomings involving animals are caused by Bothrops and Crotalus snakes; these are the highest risk to animals. This study reports on Bothrops and Crotalus envenomings in dogs, the main species responsible for epidemiology, pathogenesis, venom action, clinical signs, sequelae and complications, clinical pathology, necropsy findings, diagnosis, and treatment. Veterinarians must be capable of identifying the snake not only by observing its characteristics but also symptom evolution.