Topic:Poisoning
Poisoning in horses refers to the ingestion, inhalation, or absorption of toxic substances that can adversely affect their health. These substances may include plants, chemicals, medications, or environmental toxins. Poisoning can lead to a range of clinical signs, from mild gastrointestinal upset to severe neurological or systemic effects, depending on the toxin involved. Common toxic substances for horses include certain plants like oleander and yew, heavy metals such as lead and arsenic, and specific pesticides or herbicides. This page compiles peer-reviewed research studies and scholarly articles that investigate the causes, effects, diagnosis, and management of poisoning in horses.
Acute encephalopathy with concurrent respiratory and metabolic disturbances in first known parenteral human administration of flunixin meglumine and acepromazine maleate. Flunexin is a nonsteroidal anti-inflammatory drug approved for veterinary use in horses and cattle. Acepromazine is a phenothiazine derivative used in horses, dogs, and cats. Human exposure to these substances is rare. Methods: We report a case of a human injection of two equine medications, flunixin and acepromazine, which resulted in altered mental status, respiratory alkalosis, gastrointestinal bleeding, and elevation of liver transaminases in a 43-year-old woman who worked as a horse trainer. The patient intentionally self-injected these medications and subsequently presented to the Emerge...
Indigofera spicata (creeping indigo) poisoning of three ponies. Three ponies continuously grazed a pasture containing an estimated 24% Indigofera spicata (wet weight basis) for 4-6 weeks in April and May 2004. They developed ataxia, paresis, depression, muscle fasciculations, dysphagia, ptyalism and halitosis. Two also developed corneal opacity. One pony recovered with supportive treatment, but the other two were euthanased and necropsied. Neuropathology was not present in either case, but both livers had periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid-zonal hepatocytes, with mild to moderate periacinar necrosis also ev...
Oleander toxicosis in equids: 30 cases (1995-2010). To determine clinical, laboratory analysis, and necropsy findings for equids with oleander toxicosis and to identify factors associated with outcome. Methods: Retrospective case series. Methods: 30 equids. Methods: Medical records of equids with detectable concentrations of oleandrin in serum, plasma, urine, or gastrointestinal fluid samples and equids that had not received cardiac glycoside drugs but had detectable concentrations of digoxin in serum were identified via a medical records database search. Descriptive statistics were calculated for medical history, physical examination, laborato...
Identification of protoxins and a microbial basis for red maple (Acer rubrum) toxicosis in equines. The leaves of Acer rubrum (red maple), especially when wilted in the fall, cause severe oxidative damage to equine erythrocytes, leading to potentially fatal methemoglobinemia and hemolytic anemia. Gallic acid and tannins from A. rubrum leaves have been implicated as the toxic compounds responsible for red maple toxicosis, but the mechanism of action and toxic principle(s) have not been elucidated to date. In order to investigate further how red maple toxicosis occurs, aqueous solutions of gallic acid, tannic acid, and ground dried A. rubrum leaves were incubated with contents of equine ileum,...
[Vigilance for veterinary medicinal products: reports of adverse reactions in the year 2011]. 167 adverse reactions of Swissmedic-authorized veterinary medicinal products were reported during the year 2011 (2010: 160). Species and drug classes remain comparable with previous years: most of the reactions occurred following the use of antiparasitic products (39 %), antiinfectives (20 %) or non-steroidal antiinflammatory drugs (11 %) in companion animals (85 dogs and 27 cats) followed by cattle/calves (37). We received 15 cases of adverse reactions following reconverted use, 8 of them in treated cats. Additionally the Swiss Toxicological Information Centre in Zürich processed 84 enquirie...
Flow-mediated K(+) secretion in horses intoxicated with lolitrem B (perennial ryegrass staggers). To investigate the effects of lolitrem B intoxication on renal K(+) secretion in response to increased tubular flow rates. Methods: Results are derived from a repeated measure pilot study of seven horses fed non-perennial ryegrass feed for a week prior to exposing them to perennial ryegrass seed and hay that contained an average of 2 ppm lolitrem B. At the end of the control and treatment period frusemide (1 mg/kg I/V) was administered and serial fractional excretion of K(+)(FEK(+)) and fractional excretion of Na(+)(FENa(+)) calculated. Baseline concentration of aldosterone in plasma, serum K(...
Crotalariosis equorum (“jaagsiekte”) in horses in southern Mozambique, a rare form of pyrrolizidine alkaloid poisoning. Twenty-eight horses in southern Mozambique died after exhibiting severe respiratory distress. At necropsy, the overinflated lungs did not collapse, had prominent rib impressions, and were fibrotic and emphysematous. Microscopically, prominent proliferation of nonciliated epithelial (Clara) cells in the terminal bronchioles and pulmonary fibrosis were observed, indicative of chronic pneumotoxicity. Transmission electron microscopy demonstrated hyperplasia, desquamation, and apical bulging of Clara cells into the bronchiolar lumen. The outbreak was attributed to ingestion of Crotalaria dura J.M....
Concurrent ivermectin and Solanum spp. toxicosis in a herd of horses. 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...
Hepatoencephalopathy syndrome due to Cassia occidentalis (Leguminosae, Caesalpinioideae) seed ingestion in horses. Cassia occidentalis is a bush from the Leguminosae family, subfamily Caesalpinoideae, and is a toxic plant of veterinary interest due to the occasional contamination of animal rations. This report describes the clinical and histopathological findings of an outbreak of C. occidentalis poisoning in horses. Twenty mares were poisoned after consuming ground corn contaminated with 8% of C. occidentalis seeds. Of the 20 animals affected, 12 died: 8 mares were found dead, 2 died 6 h after the onset of clinical signs compatible with hepatic encephalopathy and the 2 other animals were subjected to euth...
Poisoning by Indigofera lespedezioides in horses. Poisoning by Indigofera lespedezioides is reported in horses in the state of Roraima, northern Brazil. The main clinical signs are anorexia, sleepiness, unsteady gait, severe ataxia, weakness, stumbling, and progressive weight loss. To induce the disease experimentally, a 7-year-old horse was introduced in a small paddock invaded by the plant. The first nervous signs were observed 44 days from the start of grazing. The animal was euthanized on day 59. No significant gross lesions were observed upon necropsies of the experimental horse as well as one spontaneously affected horse. Upon histologi...
Acute and long-term cardiomyopathy and delayed neurotoxicity after accidental lasalocid poisoning in horses. Horses are extremely susceptible to ionophore intoxication. Although numerous reports are available regarding monensin, little is known about lasalocid toxicity. Objective: To describe accidental lasalocid poisoning on a farm in Belgium. Methods: Eighty-one horses, of which 14 demonstrated clinical signs from day 0-21 after being fed a new concentrate batch. One horse died on day 20 and another on day 27. Methods: The most severe cases (n = 7), admitted to the clinic on day 29-46, underwent cardiac examination and blood biochemical analysis, including determination of plasma cardiac troponin...
Methiocarb poisoning of a horse in Australia. Snail bait poisoning is rare in horses. Cases have been reported, but clinical signs and subsequent prognostic indicators have been poorly documented and must be extrapolated from cases in companion animals. We describe in detail the poisoning of a horse that consumed a lethal dose of the carbamate, methiocarb. There are currently no guidelines for treating equine methiocarb toxicoses, but the principles of management are based on supportive therapy.
Nigropallidal encephalomalacia in horses grazing Rhaponticum repens (creeping knapweed). Nigropallidal encephalomalacia was diagnosed in two horses in northern Victoria that had a history of long-term pasture access to a dense growth of Rhaponticum repens. The region in which the affected horses lived had received well above average rainfall for several months preceding the poisoning. Affected horses had sudden onset of subcutaneous oedema of the head, impaired prehension and mastication, dullness, lethargy and repeated chewing-like jaw movements. Diagnosis was confirmed at necropsy, with characteristic malacic lesions in the substantia nigra and globus pallidus of the brain. This...
Equine poisoning by coffee husk (Coffea arabica L.). In Brazil, coffee (Coffea arabica) husks are reused in several ways due to their abundance, including as stall bedding. However, field veterinarians have reported that horses become intoxicated after ingesting the coffee husks that are used as bedding. The objective of this study was to evaluate whether coffee husk consumption causes intoxication in horses. Six horses fed coast cross hay ad libitum were given access to coffee husks and excitability, restlessness, involuntary muscle tremors, chewing movements and constant tremors of the lips and tongue, excessive sweating and increased respirat...
[Pyrrolizidine alkaloids and seneciosis in farm animals. Part 2: clinical signs, species-specific sensitivity, food residues, feed contamination, limit values]. At the forefront of pyrrolizidine alkaloid (PA) poisoning is the chronic ingestion of contaminated hay, which causes liver damage resulting in an ongoing fatal liver cirrhosis or in the veno-occlusive disease in liver or lung, respectively. The symptomatology of PA-poisoning is not identical for all animal species, and also includes central nervous symptoms. In affected horses significantly elevated levels of hepatogenic serum enzymes and an increase of the retention time for bromosulfophthalein indicates the fatal outcome of the intoxication. Chronic seneciosis of horses is incurable. Rabbits...
[Pyrrolizidine alkaloids and seneciosis in farm animals. Part 1: occurrence, chemistry and toxicology]. 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 ...
Outbreaks of equine grass sickness in Hungary. Equine grass sickness (EGS) occurs mainly in Great Britain, but has once been reported in Hungary. The stud which was affected by EGS in 2001 had no new cases until 2009/10, when 11 of 60 and five of 12 one- to three-year-old colts died or were euthanased due to EGS. Following a few hours in the high-risk field during the winter of 2010/11 further four cases of acute EGS were noted among these horses. The affected horses showed somewhat different clinical signs compared with the cases reported in Great Britain. Histopathological findings in these horses were consistent with EGS. In most examin...
Crotalaria medicaginea associated with horse deaths in northern Australia: new pyrrolizidine alkaloids. Crotalaria medicaginea has been implicated in horse poisoning in grazing regions of central-west Queensland, which resulted in the deaths of more than 35 horses from hepatotoxicosis in 2010. Liver pathology was suggestive of pyrrolizidine alkaloidosis, and we report here the isolation of two previously uncharacterized pyrrolizidine alkaloids from C. medicaginea plant specimens collected from pastures where the horses died. The first alkaloid was shown by mass spectometric and NMR analyses to be 1β,2β-epoxy-7β-hydroxy-1α-methoxymethyl-8α-pyrrolizidine, which, like other alkaloids previousl...
Clinical expression of lolitrem B (perennial ryegrass) intoxication in horses. 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...
Trema micrantha toxicity in horses in Brazil. After ingesting green leaves of T. micrantha, 2 horses showed apathy, locomotor deficit, blindness, recumbency, paddling, coma and death. The main gross findings were scattered haemorrhages, enhanced lobular pattern of the liver, and cerebral oedema. Histological changes included disseminated haemorrhages, massive hepatocellular necrosis, neuronal degeneration, Alzheimer type II astrocytes and cerebral perivascular oedema. Clinicopathological findings which were comparable with those observed in Trema micrantha poisoned ruminants, associated with epidemiological evidence suggested the diagnosi...
Multiple isotope forensics of nitrate in a wild horse poisoning incident. Multiple stable isotope analysis can be a powerful technique in forensic sciences. Oxygen and nitrogen isotopes were used to determine the source of nitrate that was responsible for the poisoning deaths of 71 wild horses in the Nevada desert. The nitrate was present in a water-filled hole known as 'the Main Lake depression.' Nitrate from the Main Lake depression had delta(18)O and delta(15)N values that were very positive (+32 per thousand, +37 per thousand), and Delta(17)O values of approximately +2 per thousand. The isotopic data suggested that the most probable source of the nitrate was nit...
Phosphine intoxication following oral exposure of horses to aluminum phosphide-treated feed. 66 horses were potentially exposed to phosphine (a gas) 14 hours after being fed a pelleted ration treated with aluminum phosphide. Results: 28 horses had clinical signs of profuse sweating, tachycardia, tachypnea, pyrexia, ataxia, seizures, and widespread muscle tremors. Clinically relevant laboratory findings included hypoglycemia and high plasma concentrations of lactate and ammonia and activities of gamma-glutamyl transpeptidase, aspartate aminotransferase, and alkaline phosphatase. At least 4 horses had signs consistent with hepatic encephalopathy. Necropsy findings included petechial and...
Animal poisoning in Europe. Part 2: Companion animals. This is the second in a series of three review articles on animal poisoning in Europe and focuses on cases in pet animals and horses in five European countries (Belgium, France, Greece, Italy and Spain) reported over the last decade. In the participating countries, dogs were the most commonly poisoned species, particularly younger animals. The majority of cases in companion animals resulted from exposure to insecticides, although rodenticides (especially anticoagulants and strychnine) posed a significant risk. In all five countries, horses and cats appeared to be more susceptible to plant toxi...
Incidence of animal poisoning cases in the Czech Republic: current situation. This article reports the most frequent cases of poisoning in farm animals, horses, cats, dogs, wild animals, fish and honey-bees in the Czech Republic. At present, there are fewer cases of acute poisoning caused by high doses of toxic substances but there are more and more cases of chronic poisoning as a consequence of environmental pollution.
A biological hazard of our age: bracken fern [Pteridium aquilinum (L.) Kuhn]–a review. Bracken fern (Pteridium aquilinum) is the fifth most distributed common weed species of the world. Its ecological distribution is very wide, and the plant can grow and spread successfully on many types of soil. The cover of P. aquilinum is--in some cases--remarkable (e.g., in the United Kingdom). Bracken fern contains different poisonous agents: some cyanogen glycosides, factors (agents) of antithiamine character (thermolabile thiaminase and thermostable other compounds) and factors of carcinogenic activity (first of all ptaquiloside). This paper summarises and reviews different toxicological ...
Metabolic changes associated with anaesthesia and cherry poisoning in a pony. A case of a pony with severe cyanide intoxication as a result of cherry ingestion is presented. General anaesthesia was performed for colic surgery. Severe metabolic lactate acidosis in combination with a high arterial oxygen partial pressure and clinically good peripheral perfusion parameters were the remarkable signs during anaesthesia. Severe hypothermia was obvious during recovery. Ten hours post-surgery the pony was euthanized as a result of neurological signs. The diagnosis of cyanide intoxication was made post-mortem. Conclusions: Cherry ingestion can lead to lethal cyanide intoxication...
Biomarkers for ragwort poisoning in horses: identification of protein targets. 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...
Acute lead intoxication in a pregnant mare. Lead (Pb) intoxication in horses is usually a chronic phenomenon with clinical signs associated with central nervous dysfunction. This report gives details of a case of acute Pb intoxication in a 9-year-old American Saddlebred mare with severe, progressive and ultimately fatal neurological deterioration. During the 4 days of hospitalisation, clinical signs progressed from intermittent headshaking and depression to severe, continuous, uncontrollable manic behaviour. At autopsy, three grey-coloured, hard metal particles were present in the gastrointestinal tract and subsequently found to contain...