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.

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.

Triple bothropic envenomation in horses caused by a single snake

In the present study, snakebites caused by a single Bothrops pauloensis simultaneously affecting three male adult horses are described. Whereas the first two affected horses were six years old, the third was 16 years old; they weighed respectively 555, 550 and 500 kg. All horses presented swollen muzzles. The first animal received an initial antivenom dose of 19 vials and adjuvant medication, it was also subjected to tracheostomy due to the progression of acute respiratory failure. The second and third horses respectively received 15 vials of antivenom each, in addition to adjuvant medication. Due to continuous changes in blood coagulation observed during hospitalization, the first and the second horses received five more vials of antivenom, respectively, in the second and third days of treatment. The first animal was discharged on 15th day and the other on the 8th day of hospitalization. Several factors including the main actions of Bothrops venom (coagulation, proteolytic and vasculotoxic activities), the importance of early diagnosis based on clinical history and clinical examination suggesting the diagnosis of Bothrops snakebite, the adequate doses of antivenom, and finally the immediate tracheostomy are herein discussed. The tracheostomy, required to save the life of the first horse, should only occur after the administration of antivenom and control measures for changes in blood coagulation.

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)

Laboratory evaluation of young ovines inoculated with natural or 60co-irradiated Crotalus durissus terrificus venom during hyperimmunization process

Laboratory profile of young ovines was studied in order to evaluate and compare their antiserum production from natural and Cobalt-60 irradiated Crotalus durissus terrificus (C.d.t.) venoms. The parameters analyzed included complete blood count, and urea, creatinine, aspartate aminotransferase, total proteins, albumin and globulin serum measurements. Three groups of six animals each were used. Group 1 (G1) received natural C.d.t. venom; Group 2 (G2) received irradiated C.d.t. venom; and Group 3 (G3) was used as control and did not receive venom, only adjuvants, using seven venom inoculations. During the experimental period, animals were fortnightly weighed. According to clinical and weight evaluation, sheep in post-weaning phase showed no changes in their physiological profiles but had excellent weight gain. The parameters analyzed were not statistically different (p<5 percent) among the groups tested. The hyperimmunization process was successfully accomplished with the production of specific antibodies against Crotalus durissus terrificus venom. Results bring a new possibility of utilizing ovines in the commercial production of anticrotalic serum, which may be used to treat human and animal envenomation. Its production cost may be reduced by subsequent use of hyperimmunized sheep for human consumption.

Immunological assessment of mice hyperimmunized with native and cobalt-60-irradiated Bothrops venoms

ELISA was used to evaluate, accompany, and compare the humoral immune response of Swiss mice during hyperimmunization with native and Cobalt-60-irradiated (60Co) venoms of Bothrops jararaca, Bothrops jararacussu and Bothrops moojeni. Potency and neutralization were evaluated by in vitro challenges. After hyperimmunization, immunity was observed by in vivo challenge, and the side effects were assessed. The animals immunization with one LD50 of each venom occurred on days 1, 15, 21, 30, and 45, when blood samples were collected; challenges happened on the 60th day. Results showed that ELISA was efficient in evaluating, accompanying and comparing mouse immune response during hyperimmunization. Serum titers produced with natural venom were similar to those produced with irradiated venom. Immunogenic capacity was maintained after 60Co-irradiation. The sera produced with native venom showed neutralizing potency and capacity similar to those of the sera produced with irradiated venom. All antibodies were able to neutralize five LD50 from these venoms. Clinical alterations were minimum during hyperimmunization with irradiated venom, however, necrosis and death occurred in animals inoculated with native venom

Immunization with native and cobalt 60-irradiated Crotalus durissus terrificus venom in swiss mice: assessment of the neutralizing potency of antisera

ELISA was used to evaluate, follow, and compare the humoral immune response of Swiss mice during hyperimmunization with natural and Cobalt 60-irradiated (60Co) Crotalus durissus terrificus venom. Potency and neutralization were evaluated by in vitro challenges. After hyperimmunization, immunity was observed by “in vivo” challenge and the side effects were assessed. The animals immunization with one LD50 of the venom was on days one, 15, 21, 30, and 45, when blood samples were collected; the challenges occurred on the 60th day. Results showed that ELISA was efficient in evaluating, following, and comparing mouse immune response during hyperimmunization. Serum titers produced with natural venom were similar to those produced with irradiated venom. Immunogenic capacity was maintained after 60Co irradiation. Serum produced from Crotalus durissus terrificus irradiated venom showed higher potency and neutralization capacity than that from natural venom. All antibodies were able to neutralize five LD50 from these venoms. Clinical alterations were minimum during hyperimmunization with irradiated venom

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 man 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.

Tissue necrosis after canine bothropic envenoming: a case report

The authors report a case of bothropic envenoming in a male Cocker Spaniel. The animal was bitten in the ventral thoracic region, receiving treatment 4 hours later. Clinical examination revealed an extensive, painful and area of firm edema, absence of local or systemic hemorrhage, without evident neurological alterations. Clinical diagnosis was mild bothropic envenoming. Treatment consisted of 5 vials of polyvalent snake antivenom, two vials administered intravenously and three subcutaneously.Blood clotting time was always within normal values. Two days after envenoming, the animal showed hyperthermia and received enrofloxacin (5mg/kg/24h) for 10 days and ketoprofen (1mg/kg/24h) for 5 days. Seventy-two hours after envenoming, extensive subcutaneous, muscle fiber, and skin necrosis of approximately 10 cm in diameter was observed. After débridement of necrotic tissues, the area was cleaned with antiseptic solutions. Complete healing was observed 55 days after envenoming. The authors discuss whether heterologous serotherapy is effective in preventing tissue necrosis after bothropic envenoming.