ABSTRACT.-Costa S.Z.R., Peixoto P.V., Brust L.A.C., d' Avila M.S., Santos A.M., Driemeier D., Nogueira V. A. & França T.N. 2016. [Troponin C in the immunohistochemistry detection of early regressive changes in sheep myocardium naturally poisoned by Amaranthus spinosus (Amaranthaceae).] Troponina C na detecção imuno-histoquímica de alterações regressivas precoces no miocárdio de ovinos naturalmente intoxicados por Amaranthus spinosus (Amaranthaceae). Pesquisa Veterinária Brasileira 36(2):83-89. Curso de Pós-Graduação em Medicina Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, BR-465 Km 7, Seropédica, RJ 23890-000, Brazil. E-mail: samayzillmann@gmail.com Amaranthus spp. are nephrotoxic plants popularly known as "pigweed". In cases of poisoning by these plants, the main histopathological alteration is found in the kidneys as toxic tubular nephrosis; however, in some cases, there may be cardiac changes. ECG changes associated with hyperkalemia have been described in pigs poisoned by Amaranthus retroflexus. Degeneration and necrosis of myocytes have been described in pigs poisoned by A. caudatus and sheep poisoned by A. spinosus. There are doubts regarding cardiac changes, since in most cases they are incipient and don't exhibit inflammatory reaction, which can lead to misinterpretation. For this study, paraffin blocks with tissues from a poisoning outbreak by A. spinosus in southeastern Brazil were used. The objective of the study was to detect the presence of incipient regressive changes in the myocardium of sheep poisoned by A. spinosus using anti-troponin C antibody-based immunohistochemistry. Fragments of hearts from 8 adult sheep and 2 fetuses naturally poisoned by A. spinosus were used. In the immunohistochemistry evaluation of the 8 hearts from the adult sheep there were several groups of myocytes with significant decrease or absence of immunoreactivity for anti-troponin C antibody. In most cases, these same areas on Hematoxylin and Eosin (HE) staining exhibited changes that varied from mild cellular tumefaction to increased eosinophilia, as well as loss of striation, cell lysis and karyolysis, sometimes accompanied by inflammatory infiltrate. In four cases, it was possible to notice that several small groups of myocytes exhibited decreased immunoreactivity corresponding to cells with undetectable or very subtle alterations on HE staining. The hearts of both fetuses did not exhibit areas with loss or decreased immunoreactivity for the anti-troponin C antibody. The results of this immunohistochemical evaluation confirmed the presence of incipient regressive changes and confirmed the occurrence of well-established necrotic lesions in the myocardium of sheep poisoned by Amaranthus spinosus. There was correspondence between areas where immunostaining for troponin was absent and areas with the most marked lesions obser-1 Recebido em 24 de julho de 2015Aceito para publicação em 28 de novembro de 2015 Parte da Tese de Doutorado do primeiro autor.

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ABSTRACT.-Santos A.M., Peixoto P.V., D' Ávila M.S., Peixoto T.C., França T.N., Costa S.Z.R., Cid G.C. & Nogueira V. A. 2016 Sodium monofluoroacetate (MF) is the toxic principle of several plants that cause "sudden death" of cattle in Brazil. Groups of cardiomyocites with high cytoplasmic eosinophilia are sometimes observed in animals poisoned by MF. However, this cardiac alteration is difficult to interpret, as there is no inflammatory reaction and it must be differentiated from artifacts. The present study had the objective to detect the presence of early regressive lesions in the myocardium of sheep and cattle experimentally poisoned by MF through immunohistochemistry with troponin C (cTnC). Fragments of the heart muscle from six cattle (three received, orally, single doses of 0.5mg/kg and the others, single doses of 1.0mg/ kg) and five sheep (one received, orally, single dose of 0.5mg/kg, the other two received single doses of 1.0mg/kg, one received sublethal daily doses of 0.1mg/kg for four days, and another received daily sublethal doses of 0.2mg/kg for six days) were submitted to immunohistochemistry with antibody anti-cTnC. In the cardiomyocites of cattle and sheep, it was possible to observe reduction of the expression levels for cTnC in the cytoplasm of groups of cardiac muscle fibers. Significant reduction of immunoreactivity ocurred overall in cardiomyocites that presented high cytoplasmic eosinophilia. The decrease or absence of expression for cTnC in animals poisoned by MF allowed to estabilish the difference between coagulative necrosis of cardiomyocites and artifacts caused by fixation. This indicates that this method can be used safely to identify any lesions, early regressive or not, in the myocardium independently of the cause. It is also possible to affirm that poisoning by MF as well as the one caused by "sudden death" causing plants can progress with necrotizing myocardial lesions.

Background: Peripheral neuroblast neoplasms are considered as a group of tumors derived from primitive cells of the neural crest that are progenitors of the sympathetic ganglia and adrenal medulla. Reports of neuroblastoma in dogs are scarce in English literature, and there are no reports from Brazil due to its rare occurrence or missed diagnosis, because modern techniques are often not accessible in Brazil. The aim of the present study was reported a case of metastatic peripheral neuroblastoma in a 10-month-old bitch of Canadian Shepherd breed, attended at the Small Animal Veterinary Hospital of the Federal Rural University of Rio de Janeiro (HVPA-UFRRJ).Case: A 10-month-old female dog, Canadian Shepherd breed, presenting prostration, inappetence, emesis, progressive weight loss, and difficulties in the locomotion of the pelvic limbs was brought to the Small Animal Veterinary Hospital of the Federal Rural University of Rio de Janeiro (HVPA / UFRRJ) for treatment. Palpation of the abdominal cavity revealed a mass of approximately 14.0 cm diameter in the thoracolumbar region. After the second visit to HVPA/ UFRRJ, there was worsening of the clinical condition and onset of pain and dyspnea; hence, euthanasia was performed. The dog was referred for necropsy; the examination revealed a mass measuring 40.0 × 35.0 cm in the abdominal cavity that caused displacement of the intestines and compressed the liver against the diaphragm, as well as another mass that traversed the diaphragm through the esophageal hiatus and surrounded the esophagus, aorta, and caudal vena cava. The right adrenal gland was compressed and adhered to the mass, and the left adrenal gland was not visualized. Specimens of various organs were collected, fixed in 10% buffered formalin, and processed according to routine histological technique. Immunohistochemical examination performed on mass specimens revealed positivity for the anti-CD56, anti-synaptophysin, anti-GFAP, and anti-NSE markers and negativity for the anti-chromogranin and anti-Olig2 markers. Based on pathology and immunohistochemistry findings, a diagnosis of poorly differentiated peripheral neuroblastoma was made; in addition, presence of emboli of neoplastic cells in the hepatic sinusoids and branches of the portal vein and metastasis in the spleen, lymph nodes, lung, and meninges were confirmed.Discussion: Positive results for neural markers associated with negative results for those of other small round cell tumors was considered to indicate the presence of neuroblast tumors; glioblastoma and oligodendroglioma were ruled out based on the absence of anti-Olig2 labeling, and, especially, the possibility of occurrence of pheochromocytoma was excluded based on the absence of anti-chromogranin. During necropsy, the location of the mass at the retroperitoneal space near the thoracolumbar junction, craniomedially in relation to the left kidney, was confirmed, which is compatible with the location of the adrenal gland. Metastasis in the dura mater was determined to be present based on necropsy findings alone, and neoplastic invasion through the esophageal hiatus of the diaphragm of a large part of the thoracic cavity was observed, which, to the best of our knowledge, have not been described in reports of veterinary medicine. The high rate of tumor growth and compression and invasion of adjacent tissues and organs may be considered as potential factors for unfavorable prognosis of peripheral neuroblastoma.