Topic:Toxic plants
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.
Relationship of age and season and consumption of Senecio vulgaris to LH/hCG receptors in the stallion testis. Testes were obtained from 70 colts and stallions and were pooled according to age (4 months to 23 years) to determine the relationship of age to LH/hCG receptor kinetics. The receptor concentration (Rt) increased from 0.069 x 10(-11) M/mg crude membrane fraction (CMF) for the 4-14-month pools to 0.464 x 10(-11) M for the 2-3-year-old pools. A 10-fold increase in testicular size also occurred, and so the total number of receptors per testis was significantly increased. A further increase to 1.237 x 10(-11) M/mg CMF was observed for stallions older than 5 years. No differences in binding affinit...
Clinicopathologic study of horses surviving pyrrolizidine alkaloid (Senecio vulgaris) toxicosis. 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...
Paralysis and lipofuscin-like pigmentation of farm stock caused by the plant, Trachyandra laxa var. laxa. A paralytic condition of farm stock in South West Africa, characterized by prominent neuronal and some mild extraneuronal pigmentation, is described. The distribution of the pigment, which was mainly located in the larger neurones of the brain and spinal cord, is given. Experimental evidence, obtained by feeding the plant, is presented that the condition is caused by Trachyandra laxa var. laxa. The histochemical features of the pigment proved to be compatible with a lipofuscin.
Primary gastric impaction in a pony. Primary gastric impaction developed in a pony as a result of the ingestion of persimmon seeds and mesquite beans. Clinical signs included mild abdominal pain, prolonged recumbency, anorexia, and lethargy. When medical therapy was unsuccessful, an exploratory laparotomy was performed. Previously, gastric impaction has been associated with signs of severe abdominal pain. Gastric impaction should be considered in cases of abdominal crisis of long duration and mild pain.
Haemolytic crisis associated with ragwort poisoning and rail chewing in two thoroughbred fillies. Events leading to the deaths of two fillies at pasture are described. Pasture hay containing the flowering stages of Senecio jacobea (ragwort) had been fed three to four months earlier. Paddocks were subdivided with posts and rails treated with copper chrome arsenate. Six horses on the property chewed rails spasmodically. Both fillies presented with haemoglobinurea. Values in liver of 83 mg Cu kg and kidney 35 mg Cu kg wet weight and serum 1.4 mg Cu/l together with histophathology of seneciosis support a sequence of ragwort poisoning followed by copper accumulation in liver and kidney terminat...
A review and some observations on stringhalt. A review of the literature on stringhalt in horses is presented, including the aetiology, clinical signs, pathology and treatment of this disease. Three New Zealand outbreaks of stringhalt are reported and discussed. The occurrence of these (and most previously reported outbreaks) in the late summer and autumn, and the association of the disease with various weeds, indicates a likely toxic aetiology.
[Enzootic calcinosis in the horse]. Cases of enzootic calcinosis in breeding mares in a Southwest German highland area are reported. The symptoms increased in the latter part of summer and existed in disturbances of movement, moderate kyphosis, sensitivity to palpation in the flexor tendons and, especially, the suspensory ligament, weight loss in spite of good food intake during summer-time and painful costal percussion; less clinical signs of renal and cardiac disorders were established. The sickness was caused by a high percentage of Trisetum flavescens in the feeding plants.
Suspected tremetol poisoning in horses. Of 10 horses in a heavily overgrazed pasture, 4 died within 1 week. Clinical signs included muscle tremors, ataxia, reluctance to walk, heavy sweating, and myoglobinuria. Serum creatine kinase, aspartate transaminase, and alkaline phosphatase activities were high. Histopathologic findings were nonspecific. On the basis of clinical signs, clinicopathologic findings, nonspecific histopathologic findings, the condition of the pasture, the identification of numerous white snakeroot plants from which trematone was extracted, and evidence that these plants had been heavily browsed, it was believed t...
Cynoglossum officinale (hound’s-tongue)–a cause of pyrrolizidine alkaloid poisoning in horses. The death of 10 horses was attributed to feeding dried grass hay containing hound's-tongue, Cynoglossum officinale. Affected horses developed weight loss, icterus, photosensitization, and hepatic encephalopathy. Histologic examination of the liver of 3 of the horses revealed megalocytosis, biliary hyperplasia, and fibrosis characteristic of pyrrolizidine alkaloid poisoning. Hound's-tongue was found to contain large quantities (0.6% to 2.1%, dry matter basis) of toxic pyrrolizidine alkaloids, which, when fed to a pony for 20 days, caused liver fibrosis and biliary hyperplasia.
Practical toxicologic diagnosis. Strychnine toxicosis is characterized by inducible tetanic seizures and metaldehyde poisoning by fine fasciculations progressing to generalized tremors and seizures. Intoxication with 1080 causes seizures, random running movements, vomiting, defecation, urination, acidosis and hyperglycemia. Intoxication with rodenticides causing coagulopathy is characterized by hemorrhage into body cavities but not necessarily external hemorrhage. Anticholinesterase insecticides cause salivation, urination and defecation, while chlorinated hydrocarbon insecticides cause CNS disturbances. Ethylene glycol intox...
The toxicity of Datura stramonium (thorn apple) to horses. Meal contaminated by Datura stramonium seeds at the rate of 0.5% by weight was fed to two horses. Both horses showed clinical signs of depression, anorexia, weight loss, rapid heart and respiration rates, mydriasis, polyuria, polydipsia and diarrhoea. Both recovered with treatment. Maize screenings contaminated by the seeds had been used in the manufacture of the meal.
Effects of dietary supplementation with butylated hydroxyanisole, cysteine, and vitamins B on tansy ragwort (Senecio jacobaea) toxicosis in ponies. Dried tansy ragwort, which contains pyrrolizidine alkaloids, was fed as 10% of a complete diet to ponies, with and without a mixture of additives. The additives provided a dietary supplement equivalent to 1% cysteine, 0.75% butylated hydroxyanisole, 200 micrograms of vitamin B12/kg of feed, and 5 mg of folic acid/kg of feed. The additives did not alter tansy ragwort toxicity, as assessed by survival time, liver changes, sulfobromophthalein (BSP) clearance rate, serum gamma-glutamyl transpeptidase activity, and plasma amino acid patterns. In ponies fed tansy ragwort, BSP clearance rate was a se...
The toxicity of Datura stramonium (thorn apple) to horses. Meal contaminated by Datura stramonium seeds at the rate of 0.5% by weight was fed to two horses. Both horses showed clinical signs of depression, anorexia, weight loss, rapi heart and respiration rates, mydriasis, polyuria, polydipsia and diarrhoea. Both recovered with treatment. Maize screenings contaminated by the seeds had been used in the manufacture of the meal.
Native American medicinal plants. Anemonin from the horse stimulant Clematis hirsutissima. Anemonin, the dilactone of cyclobutane-1,2-diol-1,2-diacrylic acid derived from the cyclodimerization of protoanemonin, a known blistering agent, was isolated from Clematis hirsutissima, a plant used by the Nez Perce and Teton Sioux nations as a horse stimulant.
Outbreak of ragwort (Senecio jacobea) poisoning in horses. Five out of 20 horses (25 per cent) on one farm died from an acute hepatic encephalopathy typical of ragwort toxicosis. Circumstantial evidence implicated pasture rather than hay as the principal source of the toxic alkaloids. Plasma levels of gamma glutamyl transferase (GGT) were determined on three occasions in all surviving ragwort-exposed horses. Elevated GGT levels were a useful early indicator of hepatic damage although not all horses with this biochemical sign developed clinical disease.
Fatal acorn poisoning in a horse: pathologic findings and diagnostic considerations. Acorn poisoning was diagnosed in an 11-year-old Quarter Horse with signs of severe colic, tachycardia, hyperpnea, abdominal borborygmus, rectal tenesmus, and hemorrhagic diarrhea. The diagnosis was based on history and predisposing factors, clinical signs, laboratory data, acorn husks in the feces, the urinary gallic acid equivalent concentration, and necropsy findings. The most striking pathologic changes were gastrointestinal and mesenteric edema, ulcerative enterocolitis, and nephrosis.