Pablo Estima-Silva

Aspectos epidemiológicos e padrões de lesões hepáticas em 35 surtos de intoxicação por Senecio spp. em bovinos no sul do Rio Grande do Sul

The study aimed to characterize morphological patterns of 59 liver samples of Senecio spp. poisoned cattle from 35 outbreaks, observed in southern Rio Grande do Sul, Brazil, from 2000 to 2009. The lesions were associated with epidemiological changes during these years. The climate changes concerning accumulated rain and mean temperature during the different seasons were analyzed. The macroscopic and histological lesions were classified into 6 different patterns. The macroscopic classification was made according to capsular pattern, hepatic cut surface discoloration, and the presence of nodules. The histological classification was based on the distribution of fibrosis, the amount of megalocytes in 10 high magnification fields, and on bile duct proliferation. Pattern 1 was characterized by a whitish liver, diffuse fibrosis, severe bile duct proliferation, and discrete megalocytosis; pattern 2 was characterized by nodules consisting of groups of hepatocytes surrounded by fibrosis, severe bile duct proliferation, and discrete to mild megalocytosis; pattern 3 was characterized by a macro-nodular aspect to the cut surface with hepatic lobules surrounded by a thin septa of fibrous tissue, severe bile duct proliferation, and mild megalocytosis; pattern 4 was characterized by a non-nodular surface with marble aspect, mild to severe bile duct proliferation, and megalocytosis; pattern 5 was characterized by a non-nodular surface and bridging or diffuse fibrosis, mild megalocytosis, and severe bile duct proliferation; and pattern 6 was characterized by a non-nodular surface, severe megalocytosis, discrete bile duct proliferation, and incipient fibrosis of the portal system, central vein or among hepatocyte cords. The results of macroscopic and histological liver analysis showed that patterns 1, 2 and 4 were the most frequently observed. The results of this study demonstrated that the macroscopic lesion observed in Senecio poisoned cattle is variable. Histologically this variation is related to the amount and distribution of fibrosis, megalocytosis and bile duct proliferation observed in each liver. Age of the cattle, evolution period of poisoning and clinical signs did not interfere on the pattern of lesions observed. On the other hand, climatic conditions probably had influence on increased disease prevalence due to major availability of Senecio spp. plants.

Intoxicação experimental aguda por Senecio brasiliensis em ovinos e indução de resistência à intoxicação

Sheep are more resistant to poisoning by Senecio spp. than cattle and horses. To determine whether this resistance could be induced by ingestion of small and repeated doses of the plant and to know how long the resistance could last, three experiments with fresh green leaves and stalks of Senecio brasiliensis were conducted. In Experiment 1, to determine the minimum dose for acute poisoning, single doses of 60, 80, 90, 100 and 100g/kg body weight (bw) were administered to five 1 and a half-year-old male Corriedale sheep. The sheep fed 60g/kg bw and 80g/kg bw of S. brasiliensis did not get sick; however, the sheep that received 80g/kg bw, developed mild fibrosis and megalocytosis in liver biopsies performed 90, 120 and 150 days after the end of plant administration. The sheep that received 90 and 100g/kg bw showed clinical signs of anorexia, prostration, paddling movements and abdominal pain, and died 12-48 hours after the onset of clinical signs. At their necropsy, ascites, disseminated petechiae and accentuated lobular pattern of the liver were found, and histologicaly hemorrhagic centrilobular necrosis was observed. In Experiment 2, the dose of 100g/kg bw fractionated into 2, 5 and 10 daily doses was administered to three sheep respectively. The fractioned dosage did not cause clinical signs of poisoning in any of the sheep, but periportal fibrosis and moderate megalocytosis were observed in liver biopsy performed at day 60 after the end of the plant administration. No histological lesions were observed in hepatic biopsies of sheep that received 10 daily doses of 10g/kg bw. In Experiment 3, to determine whether the sheep become resistant to the acute form of poisoning, four sheep ingested daily doses of 15g/kg bw of S. brasiliensis during 30 days and daily doses of 30g/kg bw for 10 days. On the day following the last dose of 30g/kg bw, two sheep were challenged with 100g/kg bw of the plant in a single dose. No clinical signs were observed in both sheep and no histological lesions could be found in the liver biopsies obtained 15 and 30 days after administration of the challenge dose. The third and fourth sheep received the challenge dose (100g/kg bw) 15 and 45 days after the end of plant administration. These animals showed anorexia, abdominal pain, and died about 12 hours after the onset of clinical signs. Gross and microscopic lesions were similar to those observed in sheep from Experiment 1. The results of this study demonstrate that sheep are susceptible to acute S. brasiliensis poisoning at doses of 90 and 100g/kg bw, but they become resistant after the continuous ingestion of small daily doses. This resistance has been lost 15 days after the end of the plant ingestion. Natural acute poisoning by S. brasiliensis probably does not occur in sheep, because they would have to eat large amounts of the plant in a short period of time.

Doenças de equinos na região Sul do Rio Grande do Sul

A retrospective study of the diagnoses of injuries and deaths in equine in Southern Brazil was conducted between 1978 and 2012. All necropsy protocols and other materials of the Regional Diagnostic Laboratory of the Veterinary School of the Federal University of Pelotas were reviewed. The collected data consisted of 2,026 equine materials, including 514 necropsy protocols of and 1,512 other biologic materials, including the protocols of biopsies, organs, swabs, feces, blood, and skin scrapings. From the resulting 2,026 diagnoses, 467 (23.05%) corresponded to neoplasms and tumor like lesions; 168 (8.29%) to parasitic diseases; 135 (6.66%) to bacterial diseases; 31 (1.53%) to viral diseases; 86 (4.24%) to diseases caused by fungi and oomycetes; 50 (2.47%) to intoxication and poisoning by mycotoxins; 9 (0.44%) to metabolic diseases; 60 (2.96%) to other diseases; and 75 (3.70%) to non-transmittable diseases of the digestive tract. Three hundred twenty cases (15.79%) were classified as diseases of unknown etiology. Other diagnoses accounted for 489 of the total 2,026 cases (24.14%). In 44 (8.56%) of the 514 necropsies and 91 (9.47%) of the 961 biopsies of organs mailed into the laboratory, the diagnoses were inconclusive, totaling 135 (9.15%) of the 1,475 in the category. This study demonstrates the importance of skin lesions in horses, as 31.88% (642) of the biopsies received were lesions on the skin of the animals. The most significant tumors observed were equine sarcoid, at 33.18%, and squamous cell carcinoma, at 7.94%. The most common observed causes of death were leucoenceflomalacia (7.59%), rabies (3.70%) thromboembolism by Strongylus vulgaris (2.33%) and monocytic ehrlichiosis (1.75%).

Senecio madagascariensis Poir. (Asteraceae): uma nova causa de seneciose em bovinos no Sul do Rio Grande do Sul

Two outbreaks of Senecio madagascariensis poisoning in cattle occurred in October 2013 in southern Brazil. Morbidity rate ranged were 3.2% and 6.1%, and lethality rate was 100%. A third case of poisoning occurred on a property in which out of 54 cattle one died with clinical signs of intoxication. In all cases, the cattle were in areas highly infested by S. madagascariensis that was in bloom. The clinical signs were diarrhea, tenesmus, opisthotonus, and progressive weight loss. Death occurred between 10 and 15 days after the onset of clinical signs. At necropsy, lesions were edema in the mesentery, in the wall of the rumen and abomasum, and in the walls of the gall bladder; the liver was firm with marbled aspect. Histologically, the liver had proliferation of fibrous connective tissue, especially in portal areas, hepatomegalocytosis, and bile duct hyperplasia. The observation of large number of S. madagascariensis in several farms in the counties of Arroio Grande, Pedro Osorio and Capao do Leao reinforces that this plant is in the process of adaptation and dissemination in this region and that other outbreaks may occur in coming years. The cases reported here apparently resulted from the consumption of the plant during the fall/winter of 2013, when it was in bloom. The quantification of alkaloids in S. madagascariensis revealed the presence of 500µg/g and 4000µg/g of pyrrolizidine alkaloids in the dry plant from two properties. It is believed that the large amount of the plant in the areas where the animals were and the amount of pyrrolizidine alkaloids found were factors that contributed to the occurrence of outbreaks.

Morte súbita em bovinos no Sul do Rio Grande do Sul: epidemiologia e diagnóstico

A survey of cases with history of sudden death in cattle was conducted in all necropsy protocols of the Regional Diagnostic Laboratory of the Veterinary School of the Federal University of Pelotas (LRD/UFPel) from 2000 to 2014. We considered animals that had died unexpectedly without prior illness or clinical signs 24 hours before death (Category 1), or before they were moved or suffered some type of management and died after falls or trembling (Category 2). We identified 72 cases (3.5%) from those two categories of a total of 2,031 materials of cattle received in LRD/UFPel. The cases occurred in all seasons of the year. In 34 cases (47.2%), affected cattle had more than four years of age, in 23 cases (31.9%) cattle had between two and three years, and in 11 cases (15.3%) they were up to one year of age. In four protocols (5.6%) age was not reported. In 62 cases (86.1%) the cattle were in an extensive grazing system, in seven (9.7%), they were in a semi-intensive grazing system, and in three cases (4.2%), they were maintained in an intensive farming system. Out of the 72 cases observed, 52 (72.2%) were classified in Category 1 and 20 (27.8%) in Category 2. The diseases that caused more often sudden death, were cerebral babesiosis (10/72), organophosphates poisoning (10/72), anthrax (7/72), bacillary hemoglobinuria (5/72), and fulguration (3/72). Out of the 18 cases considered inconclusive, just five full necropsiey were performed, and of the other 15, the material submitted was considered negative for Bacillus anthracis, and the material did not allow investigation for other diseases. The results showed that sudden deaths in southern Rio Grande do Sul are caused by diseases, mostly well-known and endemic to the region, which can be controlled or prevented by vaccination and appropriate management. Organs sent to the lab instead of the full body, limit the possibilities of conclusive diagnosis in cases of sudden death. The large number of negative cases regarding Bacillus anthracis infection was due to anthrax being a frequent suspicion when cattle appear dead without clinical signs, and the result of sending inappropriate material for the right diagnosis.

Tétano em bovinos no sul do Rio Grande do Sul: estudo de 24 surtos

Twenty-four outbreaks of tetanus occurred in 2009 in beef cattle on farms located in the region of influence of the Regional Diagnostic Laboratory (LRD), southern Rio Grande de Sul, are described. All herds were submitted to vaccination and/or application of anthelmintics between 8 and 25 days before the onset of clinical signs of tetanus. Those were prolapse of the third eyelid, stiff gait, recumbency with limbs extended and off the ground (spastic paralysis), very open eyelids, salivation, hyperexcitability, erect ears, mandibular trismus, food accumulation in the oral cavity, and presence of foam in mouth and nostrils in some cases. At postmortem some animals had necrosis, edema and hemorrhage surrounded by purulent exudate in the muscles where some medicine had been applied. Blood serum and muscle fragments of affected animals were collected for subsequent inoculation into mice. No changes were evident in histological examination. The clinical and epidemiological data associated with the absence of histological lesions allowed the diagnosis of tetanus. The infection probably occurred during the vaccination procedure, by intramuscular injections using contaminated needles. Although tetanus is not an important disease in the region, outbreaks could occur depending on epidemiological conditions. Appropriate care should be taken to avoid major economic losses as those that occurred in 2009 in the region.