Transmammary transfer of toxicity to nursing kids from Isocoma pluriflora (rayless goldenrod) dosed to lactating goats.

Rayless goldenrod (RG; Isocoma pluriflora) poisons livestock in the southwestern U.S., west Texas, and northern Mexico. The putative toxin(s) have historically been thought to be benzofuran ketones. Goats have been used successfully as a model of RG poisoning. The transmammary transfer of toxicity to offspring from lactating goats has not been studied, thus the objective of this study was to determine if nursing kids would become poisoned via mother's milk when the dams were dosed with RG. Twelve lactating goats (6 controls and 6 treated; all with twin kids) were dosed via oral gavage with alfalfa or rayless goldenrod at 2% of BW per day for 14 days. Two kids showed overt clinical signs near the end of the study; however, no dams showed clinical signs, and none developed exercise intolerance or muscle weakness. After day 11 of treatment, the RG kids showed increased (P < 0.05) serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), and creatinine kinase (CK) activities until exposure to the plant via mothers' milk ended. Serum CK activity of kids declined rapidly over 7 days after transmammary exposure ended. Histopathology revealed that one kid had extensive myonecrosis that involved both myocardium and skeletal muscles. The other kids from RG-treated does had minimal myocyte degeneration and necrosis characterized by individual myofiber swelling, hypereosinophilia and loss of striation. Benzofuran ketones were not detected in the milk of lactating goats; further, dosing with RG did not alter milk composition. In summary, milk ingestion from does dosed with >300 mg/kg BW of benzofuran ketones from RG over 14 days increased mean CK concentrations in treated kids compared to controls; however kids rapidly recovered when exposure ended. Additional work is needed to better define benzofuran ketone metabolism, toxicity, and animal susceptibility.

Senecio madagascariensis Poir. (Asteraceae): uma nova causa de seneciose em bovinos no Sul do Rio Grande do Sul / Senecio madagascariensis Poir. (Asteraceae): a new cause of seneciosis in cattle in Southern Brazil

Descrevem-se dois surtos de intoxicação por Senecio madagascariensis Poir. diagnosticados em bovinos em outubro de 2013 na região sul do Rio Grande do Sul. A morbidade foi de 3,2% e de 6,1% respectivamente e a letalidade foi de 100%. Um terceiro caso da intoxicação ocorreu em uma propriedade na qual de 54 bovinos um morreu com sinais clínicos da intoxicação. Em todos os casos, os bovinos estavam em áreas altamente infestas por S. madagascariensis que se encontrava em floração. Os sinais clínicos caracterizaram-se por diarreia, tenesmo, opistótono e emagrecimento progressivo e a morte ocorreu entre 10 e 15 dias após o início dos sinais clínicos. Nas necropsias as lesões eram de edema do mesentério, das paredes do abomaso e do rúmen, e das paredes da vesícula biliar, além de fígado firme e com aspecto marmorizado. Histologicamente havia no fígado proliferação de tecido conjuntivo fibroso, principalmente nos espaços porta, megalocitose e hiperplasia de ductos biliares. A observação de grande quantidade de S. madagascariensis em várias propriedades nos municípios de Arroio Grande, Pedro Osório e Capão do Leão a partir do ano 2013 sugere que esta planta está em pleno processo de adaptação e disseminação nesta região e que outros surtos podem ocorrer nos próximos anos. Os surtos relatados aparentemente resultaram do consumo da planta durante o outono/inverno de 2013, quando a mesma estava já em floração. A quantificação dos alcaloides revelou a presença de 500 µg/g e 4000µg/g de planta seca de alcaloides pirrolizidínicos em duas das três propriedades com casos de seneciose. Acredita-se que a grande quantidade de planta existente nas áreas onde os animais estavam e a quantidade de alcaloides presentes na mesma foram fatores que determinaram a ocorrência dos surtos...

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 Osório and Capão do Leão 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...

Toxic equine parkinsonism: an immunohistochemical study of 10 horses with nigropallidal encephalomalacia.

Chronic ingestion of yellow star thistle (Centaurea solstitialis) or Russian knapweed (Acroptilon repens) causes nigropallidal encephalomalacia (NPE) in horses with an abrupt onset of neurologic signs characterized by dystonia of lips and tongue, inability to prehend food, depression, and locomotor deficits. The objectives of this study were to reexamine the pathologic alterations of NPE and to conduct an immunohistochemistry study using antibodies to tyrosine hydroxylase and α-synuclein, to determine whether NPE brains show histopathologic features resembling those in human Parkinson disease. Results confirm that the NPE lesions are located within the substantia nigra pars reticulata, sparing the cell bodies of the dopaminergic neurons in the substantia nigra pars compacta, and in the rostral portion of the globus pallidus, with partial disruption of dopaminergic (tyrosine hydroxylase-positive) fibers passing through the globus pallidus. No abnormal cytoplasmic inclusions like the Lewy bodies of human Parkinson disease were seen in these NPE brains. These findings indicate that equine NPE may serve as a large animal model of environmentally acquired toxic parkinsonism, with clinical phenotype directly attributable to lesions in globus pallidus and substantia nigra pars reticulata rather than to the destruction of dopaminergic neurons.

The pathology of acute Nolletia gariepina poisoning of cattle.

Toxicity in cattle by the shrub Nolletia gariepina was induced experimentally by intraruminal administration of 3 g/kg dried, milled plant material as a single dose. The animals had to be starved for 24 hours before dosing, as dosing on a full rumen did not induce any signs of toxicity during 5 days of observation and clinical pathology monitoring. Clinical signs were not specific and varied according to the duration (acute versus subacute) of the toxicological process. Clinical pathological parameters indicated renal and to a lesser extent hepatic damage, with raised serum concentrations of urea, creatinine, aspartate aminotransferase (AST) and gamma glutamyl transferase (GGT). Increased urinary sodium and potassium concentration and GGT activity, as well as proteinuria, were evident. Histological and electron microscopic examinations revealed acute renal tubular epithelial cell degeneration and necrosis, especially of the proximal convoluted tubules. Mild hepatocellular degeneration was also noticeable.

Poisoning by Centratherum brachylepis in ruminants.

A disease causing anorexia and ruminal indigestion in cattle and goats, and also edema of the lips, tongue and face in goats, was associated with the ingestion of Centratherum brachylepis in pastures containing large amounts of the plant. On 3 farms with a total of 217 cattle and 140 goats, 57 (26%) cattle and 56 (40%) goats were affected, and 11 (5%) cattle and 34 (24%) goats died. In one cow that died there were widespread and severe histologic lesions in the rumen that consisted of vacuolation and ballooning degeneration of keratinocytes, and vesicle and pustule formation in the epithelium. C. brachylepis was administered orally to 3 sheep and 11 goats. Clinical signs similar to those observed in spontaneous field cases in goats were reproduced in 2 sheep and 3 goats that ingested 30-50 g/kg body weight of the plant when administered within 48 h of it being collected. C. brachylepis collected between 2 and 13 days prior to being administered caused no clinical signs in 1 sheep and 8 goats at dose rates of 30-300 g/kg body weight of the plant. These feeding studies provide evidence that C. brachylepis is the cause of the field disease observed and that the plant loses toxicity after harvesting.

Alpaca plant poisonings: nitrate-nitrite and possible cyanide.

Nitrate-nitrite poisoning killed four adult alpacas and induced the abortion of a full-term fetus after access to oaten hay (Avena sativa) containing 3.2% KNO(3) equivalent in dry matter. Necropsy findings were cyanosis, dark-coloured blood, and pulmonary congestion and oedema. Aqueous humour from two adults contained 25 mg NO(3)/L and that from the fetus contained 10 mg NO(3)/L. Cyanide poisoning possibly killed two adult wether alpacas that ate a garden-cultivated variety of Osteospermum ecklonis (South African daisy, bietou) with a cyanide potential of 6800 mg HCN/kg dry matter.

Stringhalt in Brazilian horses caused by Hypochaeris radicata.

Two outbreaks of Hypochaeris radicata-induced Australian stringhalt involving two farms and seven horses from southern Brazil are reported here. Subsequently, the disease was experimentally reproduced in a feeding trial with one colt fed H. radicata from the suspect paddocks. Fresh H. radicata was fed to the experimental animal for 50 days at an average daily dosage of 9.8 kg. Initially, the plant was collected from the paddock where the clinical disease occurred and was fed for 19 consecutive days producing mild clinical signs. However, on days 20-23 fresh plant was collected from a neighboring farm where the disease had not been reported and fed to the colt at which time the colt appeared to recover. Therefore, plant collections from the original suspect paddock resumed and feeding trials continued with clinical signs reoccurring by day 36, and increasing in intensity from days 43-50 after which plant administration was stopped. Within 15 days after ending the feeding trial with H. radicata, the colt appeared to have recovered. This experimental reproduction of stringhalt in a single colt fed H. radicata demonstrated that the two outbreaks of the disease resulted from this plant. Interestingly, the change in location for collection of plant material 19 days into the treatment, and the subsequent recovery of the colt, would suggest that plant material may differ in toxicity depending on location.

Toxicity, pathophysiology and pathology in sheep following dosing of the nephrotoxic plant Nolletia gariepina (DC) Mattf.

Ingestion of the plant Nolletia gariepina was confirmed as the cause of acute mortalities in cattle in the Kuruman area of the Northern Cape Province of South Africa. The aim of this trial was to investigate the toxic effects of this plant with respect to clinical signs, pathophysiology and pathology using the sheep as a model. At dosages of 1.5 g dried, milled plant material/kg body mass there were no detectable abnormal findings, while at dosages of 2.8-3.0 g/kg most of the animals died acutely. In subacutely affected sheep, depression, inappetance, teeth grinding, tachycardia, weak ruminal movements and recumbency were noticed. The most prominent pathophysiological changes observed, included a sharp rise in non-protein nitrogen substances in the plasma, remarkable decline in glomerular filtration rate, increase in sodium and potassium excretion, and a rise in urine gamma glutamyltransferase activity. Macroscopically a severe nephrosis was present in all the animals. The most important findings detected histologically were necrosis of the proximal convoluted tubular epithelium and large numbers of protein casts in the lumens.

Continuous exposure to an aversive mixture as a means of maintaining aversion to vermeerbos (Geigeria ornativa O. Hoffm.) in the presence of non-averted sheep.

Continuous exposure to an aversive mixture was investigated as a means of maintaining aversion to vermeerbos in sheep subjected to the social influence of non-averted sheep. The use of an aversive mixture was based on a hypothesis that continuous exposure to an acceptable aversive mixture (containing both the aversive substance and the identification factors of vermeerbos mixed with maize meal) would tempt sheep to consume small quantities of the aversive mixture each day and that this would keep them averted to vermeerbos, despite the social influence of non-averted sheep. Persistent aversion to a vermeerbos-maize meal mixture (1:99 by mass) by sheep continuously exposed to such an aversive mixture, after an initial aversion conditioning with lithium chloride (LiCl, 160 mg/kg BM), was demonstrated. Aversion in adjacent controls not exposed to the aversive mixture only lasted for some time. A similar result was obtained when sheep were challenged for intake of a pure stand of established vermeerbos. Three sheep continuously exposed to an aversive mixture after an initial aversion conditioning totally refused grazing the vermeerbos during a 42-day trial, despite the social influence of three non-averted control sheep grazing vermeerbos on an adjacent site. These results were confirmed by a second replication the following year. Joint grazing for an hour a day by averted and non-averted sheep during the last seven days of this replication also resulted in total avoidance of vermeerbos by the averted animals, despite continued intake of vermeerbos by the control sheep

Baccharis megapotamica var Weirii poisoning in Brazilian cattle.

Three Holstein heifers died after consumption of Baccharis megapotamica var weirii in southern Brazil. Main histologic lesions included degeneration and necrosis of the epithelium from the forestomachs and of the lymphoid tissue of the spleen and lymph nodes.