Toxicity in horses refers to the adverse effects that occur when horses are exposed to harmful substances, which can include plants, chemicals, medications, or environmental toxins. These toxic substances can lead to a range of clinical symptoms, from mild discomfort to severe health issues, depending on the type and amount of toxin ingested or absorbed. Common toxins affecting horses include certain plants like ragwort and yew, as well as chemicals such as pesticides and heavy metals. Veterinary diagnostics often involve identifying the toxin, understanding its mechanism of action, and determining its impact on equine health. This page compiles peer-reviewed research studies and scholarly articles that investigate the sources, effects, and management of toxicity in horses.
Georgi JR, Rendano VT, King JM, Bianchi DG, Theodorides VJ.Albendazole was effective in destroying Strongylus vulgaris larvae in verminous lesions of the cranial mesenteric artery when administered as a 20% suspension by stomach tube to ponies. Fifty mg/kg body weight administered twice a day for 2 days caused death and gradual disintegration of larvae over a period of 3 to 6 weeks with mild toxic signs appearing in 3 of 11 ponies. Higher total doses of albendazole (50 mg/kg twice a day for 4 days and 25 mg/kg three times a day for 5 days) lead to more rapid disintegration of the larvae but fatal toxicity was observed in 3 of 6 ponies so treated. In a...
Keeler RF, Balls LD, Shupe JL, Crowe MW.Cows, ewes, and mares varied considerably in susceptibility to toxicoses from the oral administration of the piperidine alkaloid, coniine. Cows were most susceptible and ewes least. Only calves had teratogenic effects from maternal administration of coniine during gestation; lambs and foals were apparently resistant. Results suggest that the marked differences between cattle and sheep are probably not due to variation in gut absorption or rumen metabolism.
Jeffcott LB, Colles CM.The clinical uses and side-effects of phenylbutazone in man, horses, and other animals are reviewed. The blood dyscrasias commonly described in man have not been reported in the horse, although several of the more minor side-effects have occasionally been seen (e.g. water retention, depression, transient staggering and phlebitis). Despite the lack of documented evidence, the toxicity of phenylbutazone in the horse is considered to be lower than that in man. This may be associated with the lower dose rates normally used, the more rapid plasma clearance rate and the comparatively younger age of ...
Ostrowski SR, Gunter EW, Matte TD.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...
van den Bogaard AE, Thijssen HH, Hemker HC.The anticoagulant, warfarin, has been reported to be effective as treatment for navicular disease in horses. Since other forms of treatment for this disease are palliative, this new anticoagulant therapy has become widely employed. Despite the fact that initiation of anticoagulant therapy is relatively simple, attending veterinary practitioners should be aware that careful monitoring of this therapy is required for both safety and efficacy. Navicular disease is an example of equine thrombotic disease, and the goal of warfarin therapy is the prevention of new thrombus formation, while at the sa...
Pinnell EF, Her J, Gordon D, Kinsella HM, Langston CE, Toribio RE.An adult American Quarter Horse mare presented for pigmenturia and lethargy of 12 hours' duration and was diagnosed with silver maple leaf toxicity. The mare had intravascular hemolysis and azotemia. The mare was treated with a transfusion of whole blood, fluids administered IV, antibiotics, oxygen insufflation, and supportive care. The azotemia persisted despite conventional medical management and hemodialysis was elected. After 2 intermittent hemodialysis treatments over 3 days, the azotemia almost resolved, clinical signs improved, and the mare was discharged. The blood urea nitrogen, c...
Snow DH, Douglas TA.The absorption characteristics of a new paste preparation of phenylbutazone were studied in ponies and thoroughbreds. The results suggested that at a similar dose rate of 5 mg/kg greater bioavailability results from the paste than from a powder preparation. Delivery of an accurate dosage of the paste was not possible using the multidose applicator. Repeated administration of the paste preparation (5 mg/kg twice daily) indicated that it is more toxic to both ponies and thoroughbreds than a powder preparation. In addition to the toxic manifestations previously reported, a neutropenia developed d...
Hovda LR.This article provides information on the toxicity of some therapeutic drugs, illicit drugs, and supplements. Medications in the therapeutic section are grouped into antibiotics, antipsychotic agents, bronchodilators, nonsteroidal anti-inflammatory drugs, opioids, and sedatives/tranquilizers. The section on illicit drugs and supplements provides information on more specific medications including commonly used or abused human medications and a few that are available only from Internet compounding pharmacies. Many drugs and supplements can be either therapeutic or illicit depending on the dosage ...
