Topic:Toxicology
Toxicology in horses involves the study of substances that can cause adverse effects when introduced to the equine body. This field examines the sources, mechanisms, and outcomes of exposure to toxic agents, which may include plants, chemicals, drugs, and environmental toxins. Understanding toxicology is essential for identifying and managing poisoning cases in horses. Research in this area often focuses on the identification of toxic compounds, their metabolic pathways, and the clinical symptoms associated with exposure. This page compiles peer-reviewed research studies and scholarly articles that explore the detection, effects, and management of toxic substances in equine health.
Acute hemolytic anemia induced by oral administration of indole in ponies. Eight ponies were allotted to 2 groups of 4. Group-1 ponies (1-4) were given 0.2 g of indole/kg of body weight orally and group-2 ponies (5 to 8) were given 0.1 g of indole/kg. Various physical, hematologic, and physiologic measurements were obtained after administration of indole. Intravascular hemolysis and hemoglobinuria were detected in both groups within 24 hours of dosing. Hemolysis was reflected by decreases in PCV, hemoglobin concentration, and RBC count, and an increase in indirect bilirubin. Erythrocyte fragility appeared to increase in both groups at 8 hours after dosing and peaked ...
Detection and identification of loline and its analogues in horse urine. Several kinds of loline-type alkaloids, norloline, loline, N-acetylnorloline, N-acetylloline, N-formylnorloline, N-formylloline and N-methylloline were detected in the urine of race-horses. Furthermore, a new compound of the alkaloids, N-senecioylnorloline, was also found and identified. These compounds were mainly identified by means of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-fourier transform-infrared spectrometry (GC-FT-IR). A certain plant of Gramineae containing four kinds of loline-type alkaloids was found in a bale of hay used for the horse forage. The taxono...
Survey of fumonisin production by Fusarium species. Fumonisins B1 (FB1) and B2 (FB2), two structurally related mycotoxins with cancer-promoting activity, were recently isolated from corn cultures of Fusarium moniliforme MRC 826. These toxins have been reported to be produced also by isolates of F. proliferatum. Contamination of foods and feeds by F. moniliforme has been associated with human esophageal cancer risk, and FB1 has been shown to be the causative agent of the neurotoxic disease leukoencephalomalacia in horses. Because of the toxicological importance of the fumonisins, the potential to produce FB1 and FB2 was determined in a study of ...
Urinary excretion of theobromine in horses given contaminated pelleted food. A high pressure liquid chromatographic (HPLC) method for measuring the theobromine content in cocoa husks, pelleted food and horse urine is described. Starting with 2 ml of urine, concentrations of 500 ng/ml could easily be detected. When feed containing 38.4 mg of theobromine was given twice daily to horses for 2 1/2 days, two days were needed after the last intake before the theobromine concentrations fell below the threshold value of 2 micrograms/ml. The time at which the peak excretion rate occurred varied from 2 to 12 h after the last administration, while the excretion rate seemed to be ...
[Ethical and analytical problems in man and greater mammals]. Toxicomania and doping give rise to an increasing number of drug measurements in the body fluids. Consequently the analysts have to face, at one and the same time, ethical and analytical problems. Should the analyst participate to investigations organised in order to disclose a toxicomania in a working place? The author suggests a positive answer as long as the adduct person benefits to a social and medical care. What is the analytical meaning of a positive test? Taking into account the increasing sensitivity of the methods used, thresholds have to be established, at least for the blood concen...
Clinical and epidemiologic features of an epizootic of equine leukoencephalomalacia. A herd of 15 mature riding horses with a history of anorexia, weight loss, and lethargy was examined. The animals had been fed a 50/50 mixture of commercial sweet feed and corn screenings contaminated with a heavy growth of Fusarium moniliforme. Thirteen of the horses had one or more neurologic signs. The most characteristic signs were profound depression and mild ataxia. Over the 19-day course of the epizootic, the horses had increasing severe neurologic deficits, including unilateral blindness and delirium. Despite the clinical appearance of dehydration, 12 horses had low PCV (16 to 27%), he...
Clinical signs, laboratory changes and toxicokinetics of brodifacoum in the horse. Six horses gavaged with a commercial brodifacoum (BDF)-containing bait (Talone) at a dosage of 0.125 mg of BDF/kg of body weight showed weight loss, severe hypocoagulability and hemogram alterations. Four of the horses became depressed and anorectic; one required vitamin K1 therapy. Increases in clotting times were observed at 24 h in the partial thromboplastin time (PTT) followed by the thrombotest (TBT) and one-stage prothrombin time (PT) at 48 h. Elevated mean PTT, PT and TBT were observed from days 4 to 8 (p less than 0.05) with levels returning to pretreatment levels by day 12. Maximum pr...
Feed additives and contaminants as a cause of equine disease. The equine practitioner often encounters serious diagnostic and therapeutic challenges regarding the specific origin of a disease. Such challenges may occur when horses become unaccountably ill after consuming what was thought to be acceptable feed but which in fact was contaminated or contained additives intended for other species. Examples of such additives and contaminants are monensin, lasalocid, salinomycin, blister beetles, and such antimicrobics as lincomycin and clindamycin.
Mineral and vitamin intoxication in horses. Horses are subject to poisoning from many sources. This article considers poisonings from minerals and vitamins of nutritional significance and from minerals as environmental contaminants.
Absence of cadmium in the blood of horses fed oats grown on municipal sludge-amended soil. Effluents from a number of industries which are typically treated in municipal sewage plants result in cadmium-containing sludge. Disposal of such sewage sludge by application to agricultural land can result in uptake of cadmium by crops. In this study, oats were grown on soils which had been amended with sewage sludge from Syracuse, New York. The cadmium concentration in the sludge-grown oats was 1.79 ppm dry weight. Horses were fed the sludge-grown oats for 6 weeks during which time blood samples were taken for the determination of cadmium. No significant differences (p greater than 0.05) we...
Blood lead and zinc protoporphyrin levels in donkeys and mules near a secondary lead smelter in Jamaica, 1987-88. During the course of an investigation into community lead poisoning near a secondary lead smelter in Jamaica, blood lead and zinc protoporphyrin levels were measured in 8 exposed and 6 (3 Jamaican, 3 US) unexposed donkeys and mules. The blood lead levels of 6 animals in the contaminated area ranged from 7.5 to 33 micrograms/dl (mean = 17.6 micrograms/dl), compared to 1.8 and 2.4 in unexposed Jamaican animals. More striking was the difference in zinc protoporphyrin levels; all 8 exposed donkeys and mules had values between 900 and 1890 micrograms/dl, compared with a range of 34-46 micrograms/dl...
Cantharidin content of two species of Oklahoma blister beetles associated with toxicosis in horses. Cantharidin content of male and female Epicauta occidentalis and E conferta was determined. Aspects of the life cycle of blister beetles, taxonomy, pheromonal and adaptive functions of cantharidin relative to the medico-legal aspects of cantharidin poisoning, prevention and control in horses are discussed.
Application of high-performance liquid chromatography–inductively coupled plasma mass spectrometry to the investigation of cadmium speciation in pig kidney following cooking and in vitro gastro-intestinal digestion. The speciation of cadmium in retail pig kidney has been examined by size-exclusion chromatography (SEC) coupled directly to inductively coupled plasma mass spectrometry (ICP-MS). Approximately 35% of the cadmium from uncooked kidney was soluble after aqueous extraction at pH 8 and SEC - ICP-MS revealed three discrete peaks whose retention times corresponded to estimated relative molecular masses of 1.2 x 10(6), 7.0 x 10(4) and 6 x 10(3)-9 x 10(3). In the cooked kidney, 35% of the Cd was soluble and was all associated with a peak of a relative molecular mass (Mr) of 6 x 10(3)-9 x 10(3). After s...
The cadmium status of horses from central Europe depending on breed, sex, age and living area. The Cd status of animals is best reflected by kidneys and much worse by liver and hair. Breed (heavy- and warm-blooded horses) only took an insignificant effect on the Cd content of kidneys and liver. On the average, however, warm-blooded horses stored more Cd than heavy ones. Geldings from Cd-exposed living areas accumulated insignificantly more Cd in liver, kidneys and hair than mares. The influence of age on the Cd content of kidneys and liver of Cd-exposed horses was significant. The Cd exposure of a living area was very well reflected by kidneys and liver. On the average, horses from two ...
The lead status of horses from central Europe depending on breed, sex, age and living area. The breed of horses took a significant effect on the Pb content of animals with a normal Pb supply. Warm-blooded horses stored more Pb in skeleton, kidneys, liver and cerebrum than heavy horses. The sex only had the trend of influencing the Pb status. Mares with a normal Pb supply incorporated more Pb than geldings. Age only took a slight effect on the skeleton. Older horses stored more Pb in the metatarsal bone than younger ones. The Pb content of horse meat was not influenced by Pb exposure. Pb was not additionally deposited in the musculature. The Pb offer of the living area took a signific...
The nephrotoxic potential of neomycin in the horse. Neomycin was administered intramuscularly to four normal adult horses at a dose rate of 10 mg/kg bodyweight every 12 h for 10 days (21 doses). The pharmacokinetic behaviour of neomycin with multiple dosing was characterised and a range of blood chemical and urinary parameters examined for evidence of nephrotoxicity. There was evidence of physical renal tubular injury (enzymuria and cylindriuria) within four days of neomycin administration but this subsided following cessation of treatment. No significant functional nephrotoxicity was detected. More severe nephrotoxicity might be expected in il...
Variations in serum sorbitol dehydrogenase, aspartate transaminase, and isoenzyme 5 of lactate dehydrogenase activities in horses given carbon tetrachloride. Seven horses were given 0.5 mg of carbon tetrachloride/kg of body weight via a nasogastric tube. Subsequent hepatocellular damage was monitored by serum enzyme determinations of sorbitol dehydrogenase, isoenzyme 5 of lactate dehydrogenase, and aspartate transaminase activities. Creatinine kinase activity was evaluated as an indicator of muscle cell damage. Sorbitol dehydrogenase, isoenzyme 5 of lactate dehydrogenase, and aspartate transaminase activities were significantly (P less than 0.05) increased by 24 hours after carbon tetrachloride administration. Isoenzyme 5 of lactate dehydrogenase a...
Toxicity of field samples and Fusarium moniliforme from feed associated with equine-leucoencephalomalacia. Feed samples of corn, pelleted feed, and oats associated with equine leucoencephalomalacia (ELEM) were obtained from North Carolina, Illinois, Indiana, and Oklahoma. These samples contained a high colony density of Fusarium moniliforme Sheldon which ranged from 64 to 87% of the total fungi. Fifty-nine F. moniliforme strains were isolated. Isolates of F. moniliforme in feed samples from Illinois, Indiana, and Oklahoma were cultured on corn. The fermented corn, mixed with regular feed and fed to one-day-old ducklings, effected a high mortality coefficient (average 55%). Methanol extracts of corn...
Etiologic agents, incidence, and improved diagnostic methods of cantharidin toxicosis in horses. In addition to the 3-striped blister beetles (Epicauta temexa and E occidentalis), other sources of equine cantharidin toxicosis were identified at the Texas Veterinary Medical Diagnostic Laboratory and included E albida and E attrivittata and the previously incriminated E pardalis and E pennsylvanica. Improved methods for diagnosing cantharidin or blister beetle toxicosis involve partial purification of urine and gastric content extracts, using silica cartridges, followed by analysis, using capillary gas chromatography/mass spectrometry. During a 26-month period, 53 episodes of cantharidin to...
Hepatotoxicity and renal toxicity in rats of corn samples associated with field cases of equine leukoencephalomalacia. Currently there is no convenient bioassay to determine the potential toxicity of corn naturally contaminated with Fusarium moniliforme. A short-term bioassay would be useful for future investigations aimed at isolating as yet unidentified toxins produced by this fungus. Two groups of five male Sprague-Dawley rats were each fed one of two F. moniliforme contaminated corn samples, designated CS-1 and CS-2, that were associated with separate field cases of equine leukoencephalomalacia (ELEM). A control group, also consisting of five male rats, was fed uncontaminated seed corn. All animals survive...
Comparative microsomal oxidation of febantel and its metabolite fenbendazole in various animal species. A comparison has been made of the in vitro metabolism of febantel (FBT) with that of one of its pharmacologically active metabolites fenbendazole (FBZ) using microsomal preparations from liver of sheep, calf, horse, pig, rat, chicken and trout. The oxidation of FBT to the corresponding sulphoxide appeared to be far more rapid with the exception of the trout, than a similar reaction with FBZ. Indeed FBT was further metabolized in several species by cyclization and further oxidation. This observation could have toxicological significance in view of the greater tetratogenic effects of the metabol...
Effects of some calcium modulators on monensin toxicity. Monensin is extremely toxic to some domestic animals, like the equine species, if they ingest poultry or cattle rations containing the drug. From a treatment standpoint, no specific compounds are known to alleviate or interact with monensin. Effects of some cardiovascular drugs which antagonize calcium influx in cardioskeletal and smooth muscles were evaluated in mice receiving varying lethal doses (80, 100, 120 or 140 mg/kg ip). Calcium channel blockers (verapamil, diltiazem and lidocaine), a calmodulin antagonist (chlorpromazine), adrenergic receptor blockers (yohimbine, tolazoline and propr...
Pyrrolizidine alkaloid-induced liver disease in horses: an early diagnosis. Nine adult horses were fed alfalfa hay cubes containing approximately 10% Senecio vulgaris until all horses had consumed approximately the same amount of toxic components of S vulgaris, pyrrolizidine alkaloids (PA). The amount of PA consumed was determined by the amount that induced clinical signs of PA toxicosis in 3 horses. The 6 other horses were given similar amounts per kilogram of body weight. An initial decrease of feed intake was observed when horses' diets were changed from alfalfa cubes to alfalfa/Senecio cubes, and feed intake was decreased further over 89 to 98 days. From 50 to 159...
Iron toxicity in neonatal foals. Newborn Shetland foals died of acute hepatic failure following oral administration of approximately 16 mg/kg body weight ferrous fumarate. Lesions in these foals were indistinguishable from lesions in foals given an oral digestive inoculant containing ferrous fumarate and were also similar to the syndrome characterised as 'toxic hepatopathy' in foals in the United States in 1983. We conclude that foals are susceptible to toxicity from low doses of iron compounds in the first few days of life. Vitamin E and selenium deficiency may contribute to this susceptibility.
Sudden and unexpected death in horses and ponies: an analysis of 200 cases. An analysis was made of the causes of death in horses and ponies over one year of age which died suddenly (Group 1) or were found dead but were considered normal when last seen (Group 2). There were 49 animals in Group 1. Thoroughbreds were overrepresented, but there were no ponies in this group. No cause of death was found in 30.6 per cent of cases and 16.3 per cent died from each of the following causes: haemorrhage in the respiratory system, central nervous system, and adverse drug reactions. Cardiovascular lesions were the cause of death in 14.4 per cent and the remaining 3.1 per cent had ...