Toxic plants are a concern in equine management as they pose health risks to horses when ingested. These plants contain various compounds that can lead to adverse effects ranging from mild discomfort to severe illness or death. Horses may encounter toxic plants in pastures, hay, or during foraging. Common toxic plants include ragwort, yew, and oleander, each containing specific toxins that affect equine physiology differently. Understanding the identification, distribution, and toxicological impact of these plants is important for prevention and management. This page compiles peer-reviewed research studies and scholarly articles that explore the identification, toxic mechanisms, and management strategies of toxic plants in relation to equine health.
Westermann CM, van Leeuwen R, van Raamsdonk LW, Mol HG.Atypical myopathy (AM) in horses is caused by the plant toxin hypoglycin A, which in Europe typically is found in the sycamore maple tree (Acer pseudoplatanus). Owners are concerned about whether their horses are in danger if they graze near maple trees. Objective: To measure hypoglycin A in the most common maple tree species in the Netherlands, and to determine whether concentration of toxin is a predictor of AM in horses. Methods: A total of 278 samples of maple tree leaves, sprouts, and seeds were classified by species. Mean concentrations of hypoglycin A were compared for the type of sampl...
Puschner B, Chen X, Read D, Affolter VK.Photosensitization, also known as photodermatitis, occurs when phototoxic or photoactive substances accumulate in the skin and interact with sunlight to result in an often severe, crusting, itching or painful dermatitis in unpigmented and/or lightly haired areas of the skin. Primary photosensitization, caused by direct ingestion of photosensitizing agents, has been reported anecdotally in horses after ingestion of alfalfa hay. Between 2004 and 2014, several large outbreaks of primary photosensitization in horses fed primarily alfalfa hay were investigated in California. Alfalfa hay samples wer...
Sander J, Cavalleri JM, Terhardt M, Bochnia M, Zeyner A, Zuraw A, Sander S, Peter M, Janzen N.Hypoglycin A (2-amino-3-(2-methylidenecyclopropyl)propanoic acid) is the plant toxin shown to cause atypical myopathy in horses. It is converted in vivo to methylenecyclopropyl acetic acid, which is transformed to a coenzyme A ester that subsequently blocks beta oxidation of fatty acids. Methylenecyclopropyl acetic acid is also conjugated with carnitine and glycine. Acute atypical myopathy may be diagnosed by quantifying the conjugates of methylenecyclopropyl acetic acid plus a selection of acyl conjugates in urine and serum. We describe a new mass spectrometric method for sample volumes of <0...
Swerczek TW.Unexplained clinical signs of weight loss and emaciation were reported in a herd of Thoroughbred horses grazing spring pastures on a central Kentucky farm, even though supplemental grain and hay were provided. Results: A buttercup plant, Ranunculus bulbosus L, was abundantly present in all pastures and paddocks on the farm. All horses, especially lactating mares and their foals, had mild to severe weight loss as assessed by body condition. Seven mares on the farm had been confirmed pregnant between 30 and 45 days of gestation, but were later found to have aborted. Two 2-year-old fillies develo...
McKenzie RK, Hill FI, Habyarimana JA, Boemer F, Votion DM.During April and May 2014 four horses aged between 5 months and 9 years, located in the Canterbury, Marlborough and Southland regions, presented with a variety of clinical signs including recumbency, stiffness, lethargy, dehydration, depression, and myoglobinuria suggestive of acute muscle damage. Two horses were subjected to euthanasia and two recovered. In all cases seeds of sycamore maple (Acer pseudoplatanus) or box elder (A. negundo) were present in the area where the horse had been grazing. Unassigned: The samaras (seeds) of some Acer spp. may contain hypoglycin A, that has been associat...
Cortinovis C, Caloni F.Alkaloids, nitrogen-containing secondary plant metabolites, are of major interest to veterinary toxicology because of their occurrence in plant species commonly involved in animal poisoning. Based on epidemiological data, the poisoning of cattle and horses by alkaloid-containing plants is a relatively common occurrence in Europe. Poisoning may occur when the plants contaminate hay or silage or when forage alternatives are unavailable. Cattle and horses are particularly at risk of poisoning by Colchicum autumnale (meadow saffron), Conium maculatum (poison hemlock), Datura stramonium (jimson wee...
Huybrechts B, Callebaut A.Pyrrolizidine alkaloids (PAs) are widely distributed plant toxins with species dependent hepatotoxic, carcinogenic, genotoxic and pneumotoxic risks. In a recent European Food Safety Authority (EFSA) opinion, only two data sets from one European country were received for honey, while one feed data set was included. No data are available for food or feed samples from the Belgian market. We developed an LC-MS/MS method, which allowed the detection and quantification of 16 PAs in a broad range of matrices in the sub ng g(-1) range. The method was validated in milk, honey and hay and applied to hon...
Baise E, Habyarimana JA, Amory H, Boemer F, Douny C, Gustin P, Marcillaud-Pitel C, Patarin F, Weber M, Votion DM.Ingestion of sycamore seeds (Acer pseudoplatanus) is the likely source of hypoglycin A in atypical myopathy (AM) but ingestion of seedlings in spring might also contribute to intoxication. Objective: To test for hypoglycin A in seeds and seedlings collected on pastures where AM cases were reported and compare its concentration in serum of affected and healthy horses. Methods: Field investigation of clinical cases. Methods: Whenever present, samaras (the winged nuts that each contain one seed) and/or seedlings were collected from pastures of 8 AM cases and 5 unaffected horses from different pre...
Lotstra RJ, van den Broek J, Power T, Marr CM, Wijnberg ID.Atrial fibrillation is a common equine arrhythmia. Quinidine alone, or with digoxin are common treatments. Studies on outcome in Warmblood populations in which duration of the AF is often unknown are limited. Objective: To identify the factors that are associated with the success of full treatment cardioversion with oral medication, and establish whether there are differences in these factors between institutions. Methods: Retrospective case series using patient records of Equine University Clinic of Utrecht University and Rossdales Equine Hospital, Newmarket. Methods: Forty-nine horses treate...
Bochnia M, Ziegler J, Sander J, Uhlig A, Schaefer S, Vollstedt S, Glatter M, Abel S, Recknagel S, Schusser GF, Wensch-Dorendorf M, Zeyner A.Hypoglycin A (HGA) in seeds of Acer spp. is suspected to cause seasonal pasture myopathy in North America and equine atypical myopathy (AM) in Europe, fatal diseases in horses on pasture. In previous studies, this suspicion was substantiated by the correlation of seed HGA content with the concentrations of toxic metabolites in urine and serum (MCPA-conjugates) of affected horses. However, seed sampling was conducted after rather than during an outbreak of the disease. The aim of this study was to further confirm the causality between HGA occurrence and disease outbreak by seed sampling during ...
Bockisch F, Aboling S, Coenen M, Vervuert I.Vitamin-D intoxication by yellow oat grass is often reported under the syndrome of enzootic calcinosis in ruminants in the upper regions of the Alps. The intake of Trisetum flavescens in ruminants and horses induces calcification of soft tissue, including vessels, tendons and ligaments, lung, heart and kidneys. Clinical symptoms, including a reluctance to move, inappetence, body-weight loss and impaired organ function, are frequently observed. To date, there are only a very few case reports about yellow-oat-grass intoxication in horses. The present case report describes Vitamin-D intoxication ...
Żuraw A, Dietert K, Kühnel S, Sander J, Klopfleisch R.Evidence suggest there is a link between equine atypical myopathy (EAM) and ingestion of sycamore maple tree seeds. Objective: To further evaluate the hypothesis that the ingestion of hypoglycin A (HGA) containing sycamore maple tree seeds causes acquired multiple acyl-CoA dehydrogenase deficiency and might be associated with the clinical and pathological signs of EAM. Methods: Case report. Methods: Necropsy and histopathology, using hematoxylin and eosin and Sudan III stains, were performed on a 2.5-year-old mare that died following the development of clinical signs of progressive muscle stif...
Hertzsch R, Emmerich IU, Lachenmeier DW, Sproll C, Monakhova YB, Aboling S, Bachmann U, Vervuert I.Opioid alkaloids were identified in the urine of horses during an anti-doping control and in a case of intoxication. In both cases, it was suspected that the horses had ingested poppy-contaminated feed. To verify this suspicion, possible opioid alkaloid sources in Germany were identified through a literature research. Additionally, the contaminated feed was botanically and chemically analysed. The results indicated that both cases were most probably caused by the poppy in the feed. This highlights the previously underestimated risk of an intake of poppy-contaminated feed in horses. Recommendat...
Holbrook TC, Gilliam LL, Stein FP, Morgan SE, Avery AL, Confer AW, Panciera RJ.Caley Pea (Lathyrus hirsutus) is potentially toxic to horses, but large case series are not reported. Objective: To describe the clinical signs of horses intoxicated with Lathyrus hirsutus and speculate on the neuroanatomical lesion localization and pathogenesis based upon the observed clinical signs. Methods: Twenty-two of 25 horses ranging in age from 6 to 34 months were affected. Five affected horses were presented to the OSUCHVS for evaluation and treatment after having been attended at the ranch by a local veterinarian (ALA). An additional horse that had been euthanized was also presented...
Robinson B, Gummow B.A disease outbreak investigation was conducted in western Queensland to investigate a rare suspected outbreak of pyrrolizidine alkaloid (PA) toxicosis in horses. Thirty five of 132 horses depastured on five properties on the Mitchell grass plains of western Queensland died in the first six months of 2010. Clinical-pathological findings were consistent with PA toxicosis. A local variety of Crotalaria medicaginea was the only hepatotoxic plant found growing on affected properties. Pathology reports and departure and arrival dates of two brood mares provided evidence of a pre wet season exposure ...
Smith S, Naylor RJ, Knowles EJ, Mair TS, Cahalan SD, Fews D, Dunkel B.Acorn toxicity has been anecdotally reported to cause fatal colitis and colic in horses but reports in the scientific literature are sparse. Objective: This study reports the diagnosis, treatment, prognosis and outcome of 9 cases with suspected acorn toxicity admitted to 2 referral hospitals. Methods: Retrospective case series. Methods: Case records from 2004 to 2013 were reviewed. Horses were included in the study if they met 3 of 4 criteria: exposure to acorns; clinical and laboratory data suggesting alimentary or renal dysfunction; acorn husks in the faeces or gastrointestinal tract; and ne...
Davis TZ, Stegelmeier BL, Hall JO.Horses are very susceptible to chronic selenosis if grazed on seleniferous forages for a prolonged period. In this study, mane and tail samples from horses that exhibited classical hoof lesions of chronic selenosis were analyzed by inductively coupled plasma mass spectrometry for selenium (Se) content. The horses had grazed for 6 months, from approximately May 15 until November 15, each year for three grazing seasons in a pasture containing seleniferous forages and water sources with elevated Se concentrations. The segmented hair samples showed a cyclic pattern in Se concentrations in the mane...
Unger L, Nicholson A, Jewitt EM, Gerber V, Hegeman A, Sweetman L, Valberg S.Hypoglycin A, found in seeds of Acer negundo, appears to cause seasonal pasture myopathy (SPM) in North America and is implicated in atypical myopathy (AM) in Europe. Acer negundo is uncommon in Europe. Thus, the potential source of hypoglycin A in Europe is unknown. Objective: We hypothesized that seeds of Acer pseudoplatanus were the source of hypoglycin A in Europe. Our objective was to determine the concentration of hypoglycin A in seeds of A. pseudoplatanus trees located in pastures where previous cases of AM had occurred. Methods: None. Methods: University of Berne records were searched ...
Brewer K, Dirikolu L, Hughes CG, Tobin T.Scopolamine (L-hyoscine) identifications, often in small-number clusters, have been reported worldwide in performance horses over the last 30 years. Scopolamine is an Association of Racing Commissioners International (ARCI) class 3, penalty class B, substance with potential to affect performance. As such, scopolamine identification(s) in race or performance horses can result in significant penalties for the connections of the horse(s). Reviewed here is the worldwide distribution of scopolamine containing plants (primarily Datura spp.), with estimates of their potential toxicity to horses throu...
Votion DM, van Galen G, Sweetman L, Boemer F, de Tullio P, Dopagne C, Lefère L, Mouithys-Mickalad A, Patarin F, Rouxhet S, van Loon G, Serteyn D....It is hypothesised that European atypical myopathy (AM) has a similar basis as seasonal pasture myopathy in North America, which is now known to be caused by ingestion of hypoglycin A contained in seeds from the tree Acer negundo. Serum from horses with seasonal pasture myopathy contained the conjugated toxic metabolite of hypoglycin A, methylenecyclopropyl acetic acid (MCPA). Methods: Retrospective study on archived samples. Objective: 1) To determine whether MCPA-carnitine was present in serum of European horses confirmed to have AM; 2) to determine whether Acer negundo or related Acer speci...
Davis TZ, Stegelmeier BL, Lee ST, Green BT, Hall JO.Rayless goldenrod (Isocoma pluriflora) sporadically poisons horses and other livestock in the southwestern United States. Similar to livestock poisoning by white snakeroot (Ageratina altissima) in the midwestern United States, previous research suggests that benzofuran ketones (BFK: tremetone, dehydrotremetone, 6-hydroxytremetone, and 3-oxyangeloyl-tremetone) are responsible for the toxicity of rayless goldenrod. However, experimental reproduction of rayless goldenrod-induced disease and detailed descriptions of poisoning in horses with known concentrations of tremetone and other BFK has not b...
Abutarbush SM.The objective of this observational study is to describe clinical, haematological and serum biochemical findings of horses affected with alfalfa dodder (Cuscuta campestris) toxicity. Twenty horses naturally exposed to alfalfa dodder toxicity were examined and information was collected on history and clinical signs. Physical examination was done on horses in the premises (n=20), and venous blood samples of 12 horses were submitted for haematology and serum biochemical examination for each horse. Abnormal clinical signs started around 36 hours after horses were fed the contaminated alfalfa. Abno...
Pessoa CR, Pessoa AF, Maia LA, Medeiros RM, Colegate SM, Barros SS, Soares MP, Borges AS, Riet-Correa F.The effects and susceptibility of donkeys to Crotalaria juncea and Crotalaria retusa poisoning were determined at high and low doses. Seeds of C. juncea containing 0.074% of dehydropyrrolizidine alkaloids (DHPAs) (isohemijunceines 0.05%, trichodesmine 0.016%, and junceine 0.008%) were administered to three donkeys at 0.3, 0.6 and 1 g/kg body weight (g/kg) daily for 365 days. No clinical signs were observed and, on liver and lung biopsies, the only lesion was a mild liver megalocytosis in the donkeys ingesting 0.6 and 1 g/kg/day. Two other donkeys that received daily doses of 3 and 5 g seed/...
Sander J, Terhardt M, Janzen N.Plants from the Sapindaceae family that are consumed by horses (maple) and humans (ackee and litchi) are known to contain the toxins hypoglycin A and methylenecyclopropylglycine which cause seasonally occurring myopathy in horses and entero-encephalopathic sickness in humans. Vertical transmission of these toxins from a mare to her foal has been described once. However the mare's milk was not available for analysis in this case. We investigated mare's milk in a similar case. Objective: We hypothesized that hypoglycin A and methylenecyclopropylglycine, like other amino acids' are secreted into ...
Renaud B, François AC, Boemer F, Kruse C, Stern D, Piot A, Petitjean T, Gustin P, Votion DM.Equine atypical myopathy (AM) is seasonal intoxication resulting from the ingestion of seeds and seedlings of the sycamore maple (Acer pseudoplatanus) that contain toxins, among them, hypoglycin A (HGA). Literature mentions several cases of AM among gravid mares and in unweaned foals. The objective of this study was to determine whether HGA and/or its metabolite are present in milk from grazing mares exposed to sycamore maple trees as confirmed by detection of HGA and its metabolite in their blood. Four mare/foal couples were included in the study. Both HGA and its metabolite were detectable i...
Kellam LL, Johnson PJ, Kramer J, Keegan KG.Signs of mild colic, intermittent lethargy, and weight loss of 6 weeks' duration in a 2-year-old Quarter Horse gelding were attributed to persimmon (Diospyros virginiana) phytobezoar formation. Diagnosis of the phytobezoar was facilitated by gastric endoscopy. Signs of gastrointestinal tract obstruction were associated with a large phytobezoar in the lumen of the stomach, gastric ulceration, and obstruction of the small intestine (as a consequence of fragmentation of the primary bezoar). Conservative treatment, using mineral oil and dioctyl sodium sulfosuccinate, was unsuccessful. A celiotomy ...
Alward A, Corriher CA, Barton MH, Sellon DC, Blikslager AT, Jones SL.Ingestion of wilted red maple leaves by horses can result in severe hemolytic anemia and methemoglobinemia. Little is known about what factors influence the outcome of red maple leaf toxicosis in horses. Objective: Our hypothesis was that physical examination findings, clinicopathologic variables or therapeutic modalities may predict outcome in horses with red maple leaf toxicity. Methods: Horses with red maple leaf toxicosis presented to referral hospitals in the southeast region of the United States. Methods: A multi-institutional retrospective study was designed to identify factors that pre...
Pfister JA, Stegelmeier BL, Gardner DR, James LF.Spotted locoweed (Astragalus lentiginosus var. diphysus) is a toxic, perennial plant that may, if sufficient precipitation occurs, dominate the herbaceous vegetation of pinyon-juniper woodlands on the Colorado Plateau. Six cow/calf pairs and four horses grazed a 20-ha pasture with dense patches of locoweed in eastern Arizona during spring 1998. Locoweed density was 0.7 plants/m2 in the pasture. Locoweed averaged 30.4% NDF and 18.4% CP. Concentrations of the locoweed toxin, swainsonine, fluctuated from 1.25 to 2 mg/g in locoweed. Horses ate more (P < 0.01) bites of locoweed than did cows (15...
Krook L, Wasserman RH, Shively JN, Tashjian AH, Brokken TD, Morton JF.A chronic debilitating disease is described in Florida horses. There is progress weight loss and lameness of increasing severity. Plasma calcium is elevated to moderate or severe degree. Anatomical changes include dystrophic calcinosis of elastic tissues, viz. major arteries, tendons and ligaments. A generalized osteopetrosis is present and may be related to hypoparathyroidsim and hypercalcitoninism. The presence of Cestrum diurnum (day-blooming jessamine, day cestrum, wild jasmin) in areas accessible to affected animals, the observation that leaves of the plant were stripped in these areas, a...
Moore RE, Knottenbelt D, Matthews JB, Beynon RJ, Whitfield PD.Ingestion of the poisonous weed ragwort (Senecio jacobea) by horses leads to irreversible liver damage. The principal toxins of ragwort are the pyrrolizidine alkaloids that are rapidly metabolised to highly reactive and cytotoxic pyrroles, which can escape into the circulation and bind to proteins. In this study a non-invasive in vitro model system has been developed to investigate whether pyrrole toxins induce specific modifications of equine blood proteins that are detectable by proteomic methods. Results: One dimensional gel electrophoresis revealed a significant alteration in the equine pl...
Ray AC, Post LO, Hurst JM, Edwards WC, Reagor JC.An analytical method for cantharidin, using high performance liquid chromatography, was applied to field specimens from horses and sheep with blister beetle (Epicauta lemniscata) poisoning. Stomach content and urine proved to be valuable aids in diagnosis. One incident of cantharidin toxicosis in ruminants (sheep) was confirmed.
Maylin G, Fenger C, Machin J, Kudrimoti S, Eisenberg R, Green J, Tobin T.Aminorex, (RS)-5- Phenyl-4,5-dihydro-1,3-oxazol-2-amine, is an amphetamine-like anorectic and in the United States a Drug Enforcement Administration [DEA] Schedule 1 controlled substance. Aminorex in horse urine is usually present as a metabolite of Levamisole, an equine anthelmintic and immune stimulant. Recently, Aminorex identifications have been reported in horse urine with no history or evidence of Levamisole administration. Analysis of the urine samples suggested a botanical source, directing attention to the Brassicaceae plant family, with their contained GlucoBarbarin and Barbarin as p...
Johnstone LK, Mayhew IG, Fletcher LR.Perennial ryegrass staggers is purported to be a common neurological mycotoxicosis of horses but the case description lacks detail and evidence. Objective: To describe the clinical syndrome of lolitrem B intoxication in horses, limiting tests to those that are applicable to clinical practice, and to assess the potential value of enzyme-linked immunosorbent assay (ELISA) tests for lolitrem B in horse body fluids. Methods: Seven horses in 2 separate groups were fed perennial ryegrass seed and hay containing 2 ppm lolitrem B. Paired data were collected prior to and after 2 weeks exposure to lol...
Sykes CA, Uzal FA, Mete A, Ochoa J, Filigenzi M, Poppenga RH, Asin J.A presumptive postmortem diagnosis of oleander () poisoning is made based on the histological observation of cardiomyocyte degeneration and necrosis, which is considered to be a reliable diagnostic marker, and can be confirmed via the detection of oleandrin in tissues or fluids. However, cardiac lesions may not be present in every case, and autolysis can often preclude the identification of subtle changes in the cardiomyocytes. Several studies of experimental oleander poisoning have noted the presence of renal lesions in multiple mammalian species, and case studies of accidental exposure have ...
McKenzie RK, Hill FI, Habyarimana JA, Boemer F, Votion DM.During April and May 2014 four horses aged between 5 months and 9 years, located in the Canterbury, Marlborough and Southland regions, presented with a variety of clinical signs including recumbency, stiffness, lethargy, dehydration, depression, and myoglobinuria suggestive of acute muscle damage. Two horses were subjected to euthanasia and two recovered. In all cases seeds of sycamore maple (Acer pseudoplatanus) or box elder (A. negundo) were present in the area where the horse had been grazing. Unassigned: The samaras (seeds) of some Acer spp. may contain hypoglycin A, that has been associat...
Butler J, Khan S, Scarzella G.Two young American miniature horses from the same farm were evaluated by a veterinarian due to presence of lethargy, anorexia, and cardiac arrhythmias. Both horses were treated aggressively with IV fluids and other supportive measures. The first horse died approximately 72 hr after the start of clinical signs and the second horse was humanely euthanized due to poor response to treatment. Oleander toxicosis was suspected based on the types of clinical signs present and due to several oleander plants and dried leaves present on the property. Oleander toxicosis was confirmed by the presence of ol...
Kalashnikov V, Zaitsev A, Atroschenko M, Miroshnikov S, Frolov A, Zavyalov O.Elemental status of 214 mares aged 3-7 years from 11 breeds was studied: Arabian purebred (n = 20), Bashkir (n = 20), Kabarda (n = 20), Vyatka (n = 20), Tuva (n = 19), Yakutsk (n = 30), Mezenskaya (n = 20), Thoroughbred (n = 20), Akhal-Teke (n = 20), Russian trotter (n = 15), Soviet Heavy Draft (n = 10) bred in 13 regions of Russia. The research objective is to study the content of chemical elements in hair from the horse's mane, depending on the sum of toxic elements in animal hair expressed in moles. The elemental composition of the hair was defined by atomic emission and mass spectrometry (...
Norman TE, Chaffin MK, Norton PL, Coleman MC, Stoughton WB, Mays T.Representatives from a herd of horses with acute onset of neurologic signs after administration of ivermectin presented for evaluation and treatment. Objective: Describe clinical signs of horses intoxicated by ingestion of Solanum sp. and administered ivermectin. Methods: Six of 11 affected unrelated horses presented for evaluation and treatment. The remaining 5 affected horses were treated at the farm. Four additional horses, housed separately, were unaffected. Methods: Case series is presented. Serum ivermectin concentrations were evaluated in the 6 hospitalized horses. The remnants of the t...
McGorum BC, Fry SC, Wallace G, Coenen K, Robb J, Williamson G, Aruoma OI.To investigate the etiology of equine dysautonomia (ED), a degenerative polyneuropathy affecting grazing horses, the biochemical composition and antioxidant/prooxidant activities of aqueous extracts of plants collected from ED pastures were determined. Plants collected immediately after an outbreak of ED had reduced antioxidant and weak prooxidant activities when compared with control plants (plants collected from ED pastures out of ED season and control plants from ED pastures that were grown under favorable conditions). ED plants also had significantly increased concentrations of fructose an...
Johnson AL, Divers TJ, Freckleton ML, McKenzie HC, Mitchell E, Cullen JM, McDonough SP.Fourteen horses at a boarding stable in Virginia were diagnosed with hepatic disease and locally grown hay was implicated as the cause. Objective: Panicum dichotomiflorum, the predominant grass species in the hay, is hepatotoxic to horses. Methods: Naturally occurring cases were adult horses of various breeds. Two healthy adult horses and 2 healthy adult sheep were used in feeding trials. Methods: Blood and liver specimens collected from affected animals during the outbreak were analyzed. Some of the affected animals were treated supportively; the main intervention was hay withdrawal. Feeding ...
Lessard P, Wilson WD, Olander HJ, Rogers QR, Mendel VE.Twenty horses of various ages had inadvertently ingested alfalfa hay contaminated with Senecio vulgaris. Among them, 4 died of liver disease. Blood was collected from affected horses at monthly intervals for 7 months and at the 9th and 14th months. The following serum enzymes and chemical items were assayed: aspartate aminotransferase, lactate dehydrogenase, alkaline phosphatase, gamma-glutamyl transferase, sorbitol dehydrogenase, total bilirubin, BUN, glucose, cholesterol, inorganic phosphate, calcium, total protein, and albumin. Amino acid profiles, conjugated bile acids, sulfobromophthalein...
Wimmer-Scherr C, Taminiau B, Renaud B, van Loon G, Palmers K, Votion D, Amory H, Daube G, Cesarini C.Equine atypical myopathy (AM) is caused by hypoglycin A (HGA) and methylenecyclopropylglycine (MCPG) intoxication resulting from the ingestion of seeds or seedlings of some Acer tree species. Interestingly, not all horses pasturing in the same toxic environment develop signs of the disease. In other species, it has been shown that the intestinal microbiota has an impact on digestion, metabolism, immune stimulation and protection from disease. The objective of this study was to characterize and compare fecal microbiota of horses suffering from AM and healthy co-grazers. Furthermore, potential d...
Petzinger E.Pyrrolizidine alkaloids belong to a class of phytotoxins which are present in more than 6000 plant species. The disease seneciosis in farm animals represents the severe poisoning by pyrrolizidine alkaloids from plants of the genus Senecio. This form of poisoning has been known since the end of the 19th century in Germany, the USA, Canada and New Zealand, and is mainly caused by Senecio jacobaea and related Senecio spp. in farm animals, including poultry. Animal poisoning by pyrrolizidine alkaloids is of worldwide importance. In Germany poisoning of horses and cattle by Senecio jacobaea, which ...
Curran JM, Sutherland RJ, Peet RL.To evaluate various biochemical tests as indicators of subclinical liver disease in horses exposed to pyrrolizidine alkaloid toxicosis. Methods: A clinical pathology field study. Methods: Twenty-two clinically normal horses from four properties in the Kimberley region of Western Australia. Methods: Serum samples from each horse were assayed for gamma glutamyltransferase, alkaline phosphatase and aspartate aminotransferase activities, and for serum bile acid concentration, albumin and total protein. Serum protein electrophoresis was performed and their amino acid profiles determined. Bromosulph...
Arzt J, Mount ME.Since 1984, a significant number of privately owned and feral horses on Easter Island have died of a syndrome consisting of progressive anorexia, weight loss, obtundation, and other central nervous system abnormalities. A single horse experiencing clinical signs of the reported syndrome was identified, examined and necropsied. Clinical signs included inappetence, emaciation, ataxia and icterus. Gross necropsy findings included hepatic enlargement and mottling, ascites and gastric impaction. Histopathological lesions included hepatic hemorrhage and necrosis, periportal megalocytosis, portal fib...
Shmalberg J, Hill RC, Scott KC.Many Chinese herbs and herbal mixtures are fed to domestic animals for their reputed medicinal properties. These herbs could contribute to the intake of essential nutrients and toxic metals, but their composition is mostly unknown. The purpose of this study was to measure major nutrient (crude protein, crude fat, carbohydrate, fibre) and mineral (Ca, P, Mg, K, Na, Fe, Zn, Cu, Mn, Mo, S, Al, Cd, Ni, Pb) concentrations in samples of fourteen combination formulas labelled for veterinary use and commonly administered to horses and dogs. Three single herbs, Bupleurum chinense, Curcuma zedoaria and ...
Puschner B, Chen X, Read D, Affolter VK.Photosensitization, also known as photodermatitis, occurs when phototoxic or photoactive substances accumulate in the skin and interact with sunlight to result in an often severe, crusting, itching or painful dermatitis in unpigmented and/or lightly haired areas of the skin. Primary photosensitization, caused by direct ingestion of photosensitizing agents, has been reported anecdotally in horses after ingestion of alfalfa hay. Between 2004 and 2014, several large outbreaks of primary photosensitization in horses fed primarily alfalfa hay were investigated in California. Alfalfa hay samples wer...
Lacerda MDSC, Wilson TM, Argenta VLS, de Araújo Pinto ÉG, E Macêdo JTSA, Soto-Blanco B, Keller KM, Ocampos Pedroso PM, Câmara ACL.The present report describes the clinical and pathological changes induced by the consumption of oats contaminated with Crotalaria spectabilis seeds by horses. Eighty horses were exposed to oats containing 10 g/kg of C. spectabilis seeds with 0.46% pyrrolizidine alkaloids, and 21 horses died within a 6-month period. Clinical signs included jaundice, apathy, a hypotonic tongue, ataxia, hyporexia, weight loss, aimless wandering, violent behavior, and proprioceptive deficits. Pathological findings were predominant in the liver and included periportal bridging fibrosis, megalocytosis, centrilobul...
Sander J, Terhardt M, Sander S, Aboling S, Janzen N.Up to now quantification of hypoglycin A in serum and urine in the range of nmols to μmols per liter plus the measurement of accumulated acyl conjugates have been used for the diagnosis of poisoning by fruits or seeds of in humans and animals. A second poison, methylenecyclopropylglycine, however, is known to occur in this material. The objective of our study was to develop and evaluate a method for the quantification of this compound suitable for test materials obtained from animals and man. Methods: Methylenecyclopropylglycine was extracted from serum and urine of a volunteer by a methanoli...
Davis TZ, Stegelmeier BL, Lee ST, Green BT, Hall JO.Rayless goldenrod (Isocoma pluriflora) sporadically poisons horses and other livestock in the southwestern United States. Similar to livestock poisoning by white snakeroot (Ageratina altissima) in the midwestern United States, previous research suggests that benzofuran ketones (BFK: tremetone, dehydrotremetone, 6-hydroxytremetone, and 3-oxyangeloyl-tremetone) are responsible for the toxicity of rayless goldenrod. However, experimental reproduction of rayless goldenrod-induced disease and detailed descriptions of poisoning in horses with known concentrations of tremetone and other BFK has not b...
Aboling S.One of the possible roles of secondary plant metabolites, including toxins, is facilitating plant-animal communication. Lethal cases of pasture poisoning show that the message is not always successfully conveyed. As the focus of poisoning lies in the clinical aspects, the external circumstances of pasture poisoning are widely unknown. To document poisoning conditions in cattle, sheep, goats, and horses on pastures and to compile a checklist of plants involved in either poisoning or co-existence (zero poisoning), published case reports were evaluated as primary sources. The number of affected a...
