Acute necrotic hepatotoxicity caused by Melanthera latifolia (Asteraceae) in cattle.

This study aims to report a spontaneous and experimental intoxication in cattle by Melanthera latifolia (Asteraceae) for the first time, and to describe its epidemiological, clinical, and pathological findings. An outbreak of acute toxic hepatopathy in cattle occurred from December of 2021 to January of 2022 in a beef cattle farm from Rio Grande do Sul state, Southern Brazil, and resulted in 94 deaths from a herd of 430 animals. At necropsy, lesions consisted of enhanced lobular pattern of the liver, transmural gallbladder edema, and hemorrhages on the surface of multiple organs. The main microscopic lesion was marked hepatocellular necrosis in the centrilobular region associated with hemorrhage and infiltration of neutrophils. During the outbreak, multiple specimens of M. latifolia were noted in the paddocks where affected cattle were grazing and many showed signs of consumption. No other known acute hepatotoxic plants were found. Two 12-month-old steers were experimentally intoxicated with a single oral dose of the fresh plant (flowers, leaves, and less fibrous stalks). One bovine ingested a dose of 10 g/kg and was euthanized after 48 h, and the other ingested 15 g/kg and was euthanized 17 h later. Clinical signs, macroscopic, and microscopic lesions in both animals were similar to those observed in the spontaneous cases. Thus, this study demonstrates that M. latifolia was the cause of the outbreak of acute toxic hepatopathy with significant mortality in cattle. M. latifolia nor any plant of the genus Melantherahad ever been reported as toxic.

Lantana camara poisoning in cattle that took refuge during a storm in a forest invaded by this plant.

An outbreak of poisoning by Lantana camara occurred in cattle when a herd sought refuge in a Eucalyptus forest heavily infested by this plant. The animals showed apathy, elevated serum activities of hepatic enzymes, severe photosensitivity, jaundice, hepatomegaly and nephrosis. After a clinical manifestation period of 2-15 days, 74 out of 170 heifers died. The main histological changes were random hepatocellular necrosis, cholestasis, biliary proliferation and, in one animal, centrilobular necrosis. Immunostaining for Caspase 3 detected scattered apoptotic hepatocytes.

Cestrum axillare (Solanaceae) poisoning in ruminants.

Cestrum axillare poisoning causes significant economic losses in farms of ruminant production due to a fatal acute hepatic disease. The consumption of C. axillare occurs on farms or pastures with a scarcity of feed or with dry forage. Epidemiological, clinical, and pathological data of poisoning outbreaks by C. axillare from 1953 to 2021 in grazing ruminants in southeastern Brazil are reported. A total of 68 bovines, two buffaloes, and two goats exhibited clinical signs and resulted in death due to C. axillare consumption, with 79% of the cases occurring during the dry period. Clinical signs were apathy, anorexia, ruminal arrest, arched back, and constipation with hard stools, sometimes with blood or mucus. Cases with neurological signs due to hepatic encephalopathy showed excitement, aggressiveness, drooling, staggering, and muscle tremors. The pathological findings included hepatocellular necrosis in the liver and microcavitations in the brain's white matter (status spongiosus). The hepatotoxins, carboxyparquin and parquin, were detected in C. axillare leaf samples collected from paddocks grazed by cattle in three southeastern Brazilian municipalities where outbreaks of C. axillare poisoning occurred. This is the first report of parquin and carboxyparquin in C. axillare.

Pascalia glauca poisoning in ruminants: Report of 12 outbreaks in northwestern Argentina.

Pascalia glauca, a perennial herb known for its toxicity in ruminants, is one of the most important toxic plants in northwestern Argentina. This work describes several outbreaks of natural intoxication with P. glauca from different sources affecting cattle, sheep and goats in different production systems, with morbidity varying between 1% and 100%. Clinical signs included tremors in the hindquarters, recumbency and death. The liver showed swelling, congestion and a mottled appearance. Histopathologic findings included centrilobular hepatocellular necrosis with hemorrhage.

[Vetch poisoning in a Bavarian cattle herd - A case report from a pathological perspective]. / Wickenvergiftung in einem bayerischen Rinderbestand.

In a herd of 40 cattle of the Holstein-Friesian breed, 6 animals were euthanized for severe pruritus, fever and skin lesions. Pathomorphological examination of 3 animals revealed multisystemic granulomatous inflammation involving multinuclear giant cells. The content of vetch in the feed used and the characteristic histology led to the diagnosis of vetch poisoning.

Spontaneous poisoning by Baccharis vulneraria Backer in cattle / Intoxicação espontânea por Baccharis vulneraria Backer em bovinos

Baccharis vulneraria Backer is a sub-shrub frequently found in southern Brazil, which leads to gastrointestinal tract intoxication. The objective of this study is to describe epidemiological, clinical and anatomopathological aspects of two cases of B. vulneraria poisoning in cattle. Two bovines from two different municipalities in the Itajaí Valley, Santa Catarina, Brazil were necropsied and performed the histopathological evaluation and botanical classification of the plant found in the pasture. Bovine 1 had dehydration, ruminal atony, diarrhea, congested mucous membranes and hypothermia for 20 hours, and died during clinical care. At necropsy, there was moderate multifocal detachment and reddening of the forestomachs mucosa. Bovine 2 presented anorexia, dry feces, ruminal atony, vocalization and muscle tremors for ten days, unresponsive to treatments, evolving to death. At necropsy were seen loosening of the mucosa with marked diffuse reddening and transmural edema. The microscopic exam revealed degeneration, necrosis, vesiculation, and detachment of the forestomachs' mucosa, associated with moderate multifocal neutrophilic infiltrate (Bovine 1); marked diffuse transmural necrosis, edema, hemorrhage, and marked fibrinous exudation (Bovine 2). A large amount of B. vulneraria was found in the pastures, with signs of consumption. In this report, a case of subacute evolution of B. vulneraria poisoning was observed, since the poisoning by this plant is usually acute. More knowledge about poisoning by this plant is necessary for the prevention and control, avoiding new mortality cases.(AU)

Baccharis vulneraria Backer é um subarbusto frequentemente encontrado no sul do Brasil, que leva a um quadro de intoxicação nocivo ao trato gastrointestinal. O objetivo deste trabalho é descrever aspectos epidemiológicos, clínicos e anatomopatológicos de dois casos de intoxicação por B. vulneraria em bovinos. Foram necropsiados dois bovinos de dois municípios do Vale do Itajaí, Santa Catarina, Brasil, com avaliação histopatológica dos órgãos e classificação botânica dos exemplares da planta localizada nos piquetes. No exame clínico do Bovino 1 foram constatados desidratação, atonia ruminal, diarreia, mucosas congestas e hipotermia durante 20 horas, com morte durante atendimento clínico. Na necropsia, havia desprendimento e avermelhamento multifocais moderados na mucosa dos proventrículos. Já o Bovino 2 teve manifestações clínicas de anorexia, fezes secas, atonia ruminal, vocalização e tremores musculares por 10 dias, não responsivas a tratamento, evoluindo para óbito. Na necropsia, havia desprendimento da mucosa dos proventrículos, com avermelhamento e edema transmural difusos acentuados. No exame histológico havia degeneração e necrose da mucosa proventricular, vacuolização e desprendimento do epitélio, infiltrado neutrofílico multifocal moderado (Bovino 1), e necrose transmural difusa acentuada, edema, hemorragia e exsudação fibrinosa acentuados (Bovino 2). Grande quantidade de B. vulneraria foi encontrada nas pastagens dos bovinos, com sinais de consumo. É relatado um caso de evolução subaguda de intoxicação por B. vulneraria, visto que a intoxicação por essa planta geralmente tem curso agudo. Conhecimentos acerca desta planta são necessários para prevenção e controle da intoxicação, evitando novos casos de mortalidade.(AU)

Spontaneous poisoning by Baccharis vulneraria Backer in cattle / Intoxicação espontânea por Baccharis vulneraria Backer em bovinos

Baccharis vulneraria Backer is a sub-shrub frequently found in southern Brazil, which leads to gastrointestinal tract intoxication. The objective of this study is to describe epidemiological, clinical and anatomopathological aspects of two cases of B. vulneraria poisoning in cattle. Two bovines from two different municipalities in the Itajaí Valley, Santa Catarina, Brazil were necropsied and performed the histopathological evaluation and botanical classification of the plant found in the pasture. Bovine 1 had dehydration, ruminal atony, diarrhea, congested mucous membranes and hypothermia for 20 hours, and died during clinical care. At necropsy, there was moderate multifocal detachment and reddening of the forestomachs mucosa. Bovine 2 presented anorexia, dry feces, ruminal atony, vocalization and muscle tremors for ten days, unresponsive to treatments, evolving to death. At necropsy were seen loosening of the mucosa with marked diffuse reddening and transmural edema. The microscopic exam revealed degeneration, necrosis, vesiculation, and detachment of the forestomachs' mucosa, associated with moderate multifocal neutrophilic infiltrate (Bovine 1); marked diffuse transmural necrosis, edema, hemorrhage, and marked fibrinous exudation (Bovine 2). A large amount of B. vulneraria was found in the pastures, with signs of consumption. In this report, a case of subacute evolution of B. vulneraria poisoning was observed, since the poisoning by this plant is usually acute. More knowledge about poisoning by this plant is necessary for the prevention and control, avoiding new mortality cases.

Baccharis vulneraria Backer é um subarbusto frequentemente encontrado no sul do Brasil, que leva a um quadro de intoxicação nocivo ao trato gastrointestinal. O objetivo deste trabalho é descrever aspectos epidemiológicos, clínicos e anatomopatológicos de dois casos de intoxicação por B. vulneraria em bovinos. Foram necropsiados dois bovinos de dois municípios do Vale do Itajaí, Santa Catarina, Brasil, com avaliação histopatológica dos órgãos e classificação botânica dos exemplares da planta localizada nos piquetes. No exame clínico do Bovino 1 foram constatados desidratação, atonia ruminal, diarreia, mucosas congestas e hipotermia durante 20 horas, com morte durante atendimento clínico. Na necropsia, havia desprendimento e avermelhamento multifocais moderados na mucosa dos proventrículos. Já o Bovino 2 teve manifestações clínicas de anorexia, fezes secas, atonia ruminal, vocalização e tremores musculares por 10 dias, não responsivas a tratamento, evoluindo para óbito. Na necropsia, havia desprendimento da mucosa dos proventrículos, com avermelhamento e edema transmural difusos acentuados. No exame histológico havia degeneração e necrose da mucosa proventricular, vacuolização e desprendimento do epitélio, infiltrado neutrofílico multifocal moderado (Bovino 1), e necrose transmural difusa acentuada, edema, hemorragia e exsudação fibrinosa acentuados (Bovino 2). Grande quantidade de B. vulneraria foi encontrada nas pastagens dos bovinos, com sinais de consumo. É relatado um caso de evolução subaguda de intoxicação por B. vulneraria, visto que a intoxicação por essa planta geralmente tem curso agudo. Conhecimentos acerca desta planta são necessários para prevenção e controle da intoxicação, evitando novos casos de mortalidade.

Clinical, pathologic, and toxicologic characterization of Salvia reflexa (lance-leaf sage) poisoning in cattle fed contaminated hay.

Salvia reflexa (lance-leaf sage)-contaminated alfalfa hay was fed to ~500 mixed-breed beef cattle. Within hours of exposure, nearly half of the cattle developed lethargy, anorexia, depression, and recumbency, followed by bellowing, colic, and death. Even though the uneaten contaminated hay was removed the first day, nearly 100 animals died within the first 48 h. Three of these cattle were examined postmortem, and tissues and hay samples were collected for microscopic and chemical analysis. Several days later, a smaller number of the clinically poisoned cattle developed neurologic disease with aberrant behavior, aggression, icterus, blindness, exhaustion, and death. A total of 165 cattle were fatally poisoned. Poisoned cattle had swollen, dark, mottled livers that had a prominent nutmeg-like lobular pattern on cut section. Histologically, there was severe centrilobular-to-panlobular hepatic necrosis with marked hepatocellular swelling, degeneration, and necrosis. The surviving cattle developed liver disease characterized by altered serum biochemical analyses and microscopic hepatocellular degeneration and necrosis. In subsequent biopsies and analysis, these lesions resolved within 6-7 mo. After confirming toxicity of the hay in cattle, goats, and mice, followed by a mouse bioassay-guided chemical fractionation process, Salvia reflexa was identified as the contaminant in the hay responsible for the hepatotoxicity. S. reflexa has not been reported previously to cause fatal hepatotoxicity in livestock in North America, to our knowledge.

Plant and Fungal Hepatotoxicities of Cattle in Australia, with a Focus on Minimally Understood Toxins.

Plant- and fungus-derived hepatotoxins are a major cause of disease and production losses in ruminants in Australia and around the world. Many are well studied and described in the literature; however, this is not the case for a number of hepatotoxicities with economic and animal welfare impacts, such as acute bovine liver disease (ABLD), brassica-associated liver disease (BALD) and Trema tomentosa, Argentipallium blandowskianum and Lythrum hyssopifolia toxicity. Additionally, significant overlap in the clinical presentation and pathology of these conditions can present a diagnostic challenge for veterinarians. This review summarizes the current and most recently published knowledge of common plant- and fungus-associated hepatotoxins affecting cattle in Australia, with a focus on the mechanisms of toxicity and distinguishing diagnostic features. Consolidation of the current understanding of hepatotoxic mechanisms in cattle provides insight into the potential mechanisms of lesser-known toxins, including cellular and subcellular targets and potential metabolic pathways. In the absence of specific etiological investigations, the study of epidemiological, clinical and pathological features of hepatotoxicity provides valuable insights into potential toxic mechanisms and is integral for the successful diagnosis and management of these conditions.

Outbreak of Oleander (Nerium oleander) Poisoning in Dairy Cattle: Clinical and Food Safety Implications.

Oleander is a spontaneous shrub widely occurring in Mediterranean regions. Poisoning is sporadically reported in livestock, mainly due to the ingestion of leaves containing toxic cardiac glycosides (primarily oleandrin). In this study, 50 lactating Fleckvieh cows were affected after being offered a diet containing dry oleander pruning wastes accidentally mixed with fodder. Clinical examination, electrocardiogram, and blood sampling were conducted. Dead animals were necropsied, and heart, liver, kidney, spleen, and intestine were submitted to histological investigation. Oleandrin detection was performed through ultra-high performance liquid chromatography-tandem mass spectrometry in blood, serum, liver, heart, milk, and cheese samples. Severe depression, anorexia, ruminal atony, diarrhea, serous nasal discharge, tachycardia, and irregular heartbeat were the most common clinical signs. The first animal died within 48 h, and a total of 13 cows died in 4 days. Disseminated hyperemia and hemorrhages, multifocal coagulative necrosis of the cardiac muscle fibers, and severe and diffuse enteritis were suggestive of oleander poisoning. The diagnosis was confirmed by the presence of oleandrin in serum, liver, heart, milk, and cheese. Our results confirm the high toxicity of oleander in cattle and report for the first time the transfer into milk and dairy products, suggesting a potential risk for the consumers.

Spontaneous poisoning by Stryphnodendron rotundifolium var. villosum in cattle / Intoxicação espontânea por Stryphnodendron rotundifolium var. villosum em bovinos

This is a report on an outbreak of cattle poisoning by Stryphnodendron rotundifolium var. villosum (Benth.) Scalon in the state of Goiás in Brazil. In a herd of 80 cattle that consumed the mature fruit of this plant that was present in their pasture, 12 animals fell ill and died. The clinical signs that they presented were apathy, progressive weight loss, reeling, bristling, and dry stools containing seeds. The main necropsy findings were jaundice, an increased lobular pattern and orange coloration in their liver, enlarged kidneys with yellowish medullae, and pre-stomachs containing fruit peels and seeds. A histopathological examination revealed vacuolar degeneration and necrosis in the liver and kidneys and vacuolar degeneration in the rumen, omasum, reticulum, and intestine. The diagnosis of poisoning by S. rotundifolium var. villosum was based on epidemiological data, clinical findings, and pathological changes. Our results can aid in the differentiation between poisoning by S. rotundifolium var. villosum and poisoning by other toxic plants that are of interest to lifestock.(AU)

Relata-se um surto de intoxicação em bovinos por Stryphnodendron rotundifolium var. villosum (Benth.) Scalon no estado de Goiás, Brasil. De um rebanho composto por 80 bovinos, os quais consumiram frutos maduros da planta presente na pastagem, 12 animais adoeceram e morreram. Os sinais clínicos apresentados foram apatia, emagrecimento progressivo, andar cambaleante, pelo eriçado e fezes secas contendo sementes. Os principais achados de necropsia foram icterícia, fígado com padrão lobular e coloração alaranjada, rins aumentados e com amarelamento da medular e pré-estômagos com presença de cascas e sementes do fruto. Ao exame histopatológico, notou-se degeneração vacuolar e necrose no fígado e rins e degeneração vacuolar no rúmen, omaso, retículo e intestino. O diagnóstico da intoxicação por S. rotundifolium var. villosum baseou-se nos dados epidemiológicos, nos achados clínicos e nas alterações patológicas. Nossos resultados podem auxiliar na diferenciação entre a intoxicação por S. rotundifolium var. villosum e a intoxicação por outras plantas tóxicas de interesse pecuário.(AU)

Cistus salviifolius Toxicity in Cattle.

Toxicity related to consumption of Cistus sp. pl. has been described in ruminants in some countries. This report describes the clinical and pathological findings of Cistus salviifolius toxicosis in 3 beef cattle herds located in 2 different areas of Sicily, Italy. Outbreaks were observed after grazing in poor winter pasture where C. salviifolius was abundant. Mean morbidity and mortality were 29% and 21%, respectively. Most of the affected animals (6 to 36 months old) showed anorexia, weight loss, and pollakiuria culminating in recumbency and death. Occasionally, abortion and neurological signs were observed. In animals with acute signs, there was a moderate decrease of sodium and chloride concentrations in serum. Animals with chronic signs showed an increase of serum urea, creatine phosphokinase (CPK), aspartate transaminase (AST), lactate dehydrogenase (LDH), and phosphorus and a decrease in total serum protein, calcium, chloride, and magnesium concentrations. Moderate anemia and slight neutropenia, lymphocytosis, and eosinophilia were detected in all groups. At necropsy, the main lesion was severe distention of the urinary bladder with turbid hemorrhagic urine and crystalluria. Histologically, chronic cystitis, interstitial nephritis, eosinophilic enteritis, and nonsuppurative necrotizing hepatitis were observed. To our knowledge, this is the first report of C. salviifolius toxicosis in cattle in Italy.

Acute fatal poisoning by spontaneous ingestion of Enterolobium contortisiliquum (Mimosidae) pods in horses.

An outbreak of acute poisoning of horses by Enterolobium contortisiliquum pods is reported in the state of Goiás, Brazil. Three horses presented apathy, hyporexia, prostration, jaundice, recumbency and died in 24-48 hours. The main pathological findings were a yellowish liver with an enhanced lobular pattern, multifocal hepatic necrosis mostly in the midzones of lobules and sometimes with a random distribution across the hepatic lobes and swelling of hepatocytes. E. contortisiliquum trees has a wide distribution in South America and cases of poisoning have not been reported in horses.

Acute heart failure in rabbits by avocado leaf poisoning.

The aim of this paper was to report an outbreak of avocado poisoning in rabbits in Salta, Argentina. Fourteen rabbits died of congestive heart failure within 30 h of ingesting fresh avocado leaves from pruned trees. They showed clinical signs of respiratory and cardiac distress. Full necropsies of four rabbits were performed and samples were collected for histopathology. The gross pathological observation included pleural and pericardial effusion, pulmonary oedema, slight ascites; the hearts appeared flabby and markedly pale. In addition, the stomach content consisted mostly of green feed with large amounts of avocado leaves. Epidermal fragments of Persea americana were identified by microhistological analysis of gastric content to get most efficiently to a correct diagnosis. Histopathological examination revealed degeneration and necrosis of myocytes and a mononuclear cellular infiltration mainly involving the myocardium and, to a lesser extent, the liver, lung and kidneys. Our observations indicate that avocado leaves should be avoided in the green diet of rabbits.

Neurological syndrome in goats associated with Ipomoea trifida and Ipomoea carnea containing calystegines.

A disease characterized by ataxia, tremors and nystagmus had been observed in goats in Nicaragua. The main histologic lesions were loss and neuronal vacuolation of Purkinje cells and Wallerian-like degeneration mainly in the cerebellum, suggesting a glycoprotein storage disease. Ipomoea carnea and Ipomoea trifida found in the paddocks were negative for swainsonine, but contained calystegines at 0.02% and 0.06% suggesting that the disease was caused by these substances, which are competitive inhibitors of ß-glucosidase and α-galactosidase activities.

Fall panicum ( Panicum dichotomiflorum) toxicosis in three juvenile goats.

Consumption of certain grasses belonging to the genus Panicum has been found to cause hepatogenous photosensitization and crystal-associated cholangiohepatopathy in small ruminants, and liver disease in horses, in many areas of the world. We describe herein the clinical findings, microscopic lesions, and steroidal saponin analysis of Panicum dichotomiflorum associated with fatal toxicosis in 3 juvenile goats in Nebraska. The disease presentation in our case was fulminant, with anorexia, marked icterus, and death for all affected animals in less than a week. Photosensitization was not observed. The microscopic lesions consisted of severe crystal-associated cholangiohepatopathy and nephropathy, with aggregates of clear or refractile and birefringent, acicular crystals present within bile ducts, macrophages, hepatocytes, and renal tubules. High-performance liquid chromatography-mass spectrometry of the grass samples demonstrated that dichotomin was the major steroidal saponin present (0.89 µg/mg); protodioscin was also present (0.059 µg/mg). The findings were consistent with ingestion of steroidal saponins, and P. dichotomiflorum was identified as the predominant forage available.

Bovine upper alimentary squamous cell carcinoma associated with bracken fern poisoning: Clinical-pathological aspects and etiopathogenesis of 100 cases.

Upper digestive tract (UDT) cancer is rare in cattle, however in Southern Brazil, the UDT squamous cell carcinomas (SCCs) are relatively common and have been associated with bracken fern consumption and the presence of papillomas. Although a theory of pathogenesis considers bovine papillomavirus type 4 (BPV-4) as a cofactor in the development of these SCCs, some aspects of the etiopathogenesis of this disease need to be more investigated. In fact, detection of BPV-4 in UDT papillomas is scarce in other regions of the world and has not been performed in Brazil. Therefore, this study had two aims: 1) to analyze the epidemiological, clinical and pathological aspects of 100 natural cases of SCCs in the UDT of cattle grazing on bracken fern (Pteridium arachnoideum) highly contaminated areas, investigating the associations between these parameters; and 2) to investigate the presence of papillomavirus DNA by polymerase chain reaction (PCR) in the UDT papillomas (n = 47) from 30 cattle that also had UDT SCCs. There were statistically significant associations between clinical signs and tumor localization in the UDT; between histological grade of differentiation and tumor localization; and a trend towards significant association between histological grade of differentiation and presence of metastases. The average age of cattle with oropharyngeal SCCs was 7.39 years, with statistically significant difference comparing to cattle with esophageal SCCs (8.6 years). No statistical association was observed among other clinical-pathological parameters (growth pattern and primary site of the tumor) analyzed. No BPV DNA was detected in papillomas by PCR. Therefore, these results suggest the possibility that papillomas of the UDT are not necessarily associated with BPV infection.

Poisoning by Brunfelsia uniflora in sheep and donkeys.

Farmers in the State of Piauí in northeastern Brazil reported nervous signs in ruminants and donkeys after ingestion of Brunfelsia uniflora at the start of the rainy season when the plant is flowering. Leaves of the plant, collected at the start or at the end of the rainy season, were administered in single doses of 5-20 g/kg body weight to 8 sheep and 3 donkeys. Two sheep and 1 donkey that ingested 10 g/kg of the plant in November at the start of the rainy season, when the plant was flowering, developed severe convulsions and diarrhea. One sheep was euthanized and autopsied, and no significant lesions were found. The other sheep and the donkey recovered. Four sheep and one donkey that ingested 10 or 20 g/kg of leaves collected in April, at the end of the rainy season, did not show clinical signs. One donkey that ingested 5 g/kg of leaves collected in November developed diarrhea and recovered. These results demonstrate the toxicity of B. uniflora for livestock and suggest that the plant is toxic at these doses only during the start of the rainy season.

Experimental poisoning by Vernonia rubricaulis in sheep.

In order to evaluate the susceptibility of sheep to V. rubricaulis and to establish the clinical signs, serum biochemistry, and pathological findings, eight sheep were fed varying doses of V. rubricaulis. The onset of clinical signs occurred 6-48 h after the ingestion of V. rubricaulis. Clinical courses lasted 6-56 h after the ingestion of the plant. Serum activities of aspartate aminotransferase, gamma-glutamyl transferase, and alkaline phosphatase were highly elevated and glucose blood levels were low in affected sheep. Clinical signs consisted of apathy, anorexia, dry muzzle, respiratory distress, abdominal pain, and mushy feces with streaks of blood and mucus. Two sheep had neurological signs including muscle fasciculation, nystagmus, paddling movements, and blindness. Liver necrosis could be detected antemortem through liver biopsy. Five sheep died and three recovered. The liver was affected in all necropsied sheep; it increased in volume and had marked accentuation of the lobular pattern with red, depressed areas intercalated with a pale yellow network. Ascites and hydropericardium were consistent findings. Microscopically, centrilobular to massive coagulative necrosis was observed. Coagulative necrosis was also observed in a few proximal renal tubules. Microscopic lesions were not found in any other organs. The severity of liver lesions was proportional to the dose. Chemical analysis to detect carboxyatractyloside in V. rubricaulis plant material was negative. It is concluded that V. rubricaulis poisoning in sheep is clinically, biochemically, and pathologically characteristic of an acute hepatoxicosis.

Neurotoxicosis in horses associated with consumption of Trema micrantha.

BACKGROUND: Trema micrantha is a tree widely distributed throughout the Americas. The tree produces highly palatable leaves that have been associated with natural poisoning in goats, sheep and horses, in which hepatic necrosis and hepatic encephalopathy have been observed. OBJECTIVES: This study describes malacia and haemorrhage in the central nervous system (CNS) due to T. micrantha consumption, with minimal to absent hepatic lesions. STUDY DESIGN: Retrospective case series. METHODS: A total of 14 horses with a history of neurological signs and spontaneous consumption of T. micrantha leaves were submitted to necropsy and multiple samples were collected for histopathology. Details of clinical history and signs of the horses were obtained through inquiries to the owners and attending veterinarians. RESULTS: All the 14 horses had neurological signs of ataxia, severe sialorrhoea, involuntary running movements, sternal and lateral recumbency, and death after a clinical course that lasted from 24 h to 9 days. For a few days prior to onset of clinical signs, all horses had spontaneously consumed, potentially toxic doses of T. micrantha leaves. All 14 brains had diffuse yellowish discoloration affecting the rhombencephalon, mesencephalon, diencephalon, telencephalon and corpus striatum. In all cases, the most severe lesions were observed in the pons. Spinal cord lesions were observed affecting the lumbar intumescence, which was swollen with darken and depressed areas at the dorsal and ventral horns, and at the sacral level, which on cut surface displayed a friable and yellowish grey matter. The lesions observed grossly in brain and spinal cord consisted microscopically of severe vasculitis and liquefactive necrosis of white and grey matter of the brainstem, cerebellum and spinal cord. MAIN LIMITATIONS: This is a small retrospective series relying on clinical observations reported by owners and attending veterinarians. The mechanism of action of the plant toxin in the CNS is still unidentified. CONCLUSION: T. micrantha poisoning in horses causes predominantly a neurological disease, with minimal to absent hepatic lesions.