Activated charcoal may be useful in treating horses in the early stages of atypical myopathy, or at risk of ingesting plant material containing the toxin behind the disease, according to researchers.
Atypical myopathy, also known as sycamore poisoning, is caused by the amino acid hypoglycin A, a toxin found in the seeds or seedlings of some Acer tree species, mainly the sycamore maple (Acer pseudoplatanus) in Europe.
Affected horses suffer muscle breakdown. The disease mainly affects the heart and muscles that control posture and breathing.
Signs include stiffness and muscle tremors, weakness, depression, breathing difficulties and sometimes colic. Urine can turn brown or red. The heartbeat can become irregular or fast.
Around three-quarters of horses die, often within two days. Veterinary support can increase survival chances, but there is no known antidote to the toxin.
Researchers in Germany, writing in the Equine Veterinary Journal, have described their investigation into the potential of absorbent materials to mop up the toxin in the digestive tract.
Jessika-Maximiliane Cavalleri and her colleagues said the increasing incidence of the disease and its high death rate created an urgent need for new therapeutic and preventative approaches.
In their laboratory work, they tested substances commonly used in equine practice – activated charcoal composition, di-tri-octahedral smectite, mineral oil and activated charcoal – for their binding capacity for hypoglycin A.
Activated charcoal composition and activated charcoal topped the candidates tested. They were, according to the researchers, potent hypoglycin A binding substances.
Subsequent testing using gut tissue pointed to the ability of activated charcoal to reduce intestinal absorption of the toxin, they said, although their lab work could not take into account factors such as transit time through the gut and intestinal content in live horses, which may affect the charcoal’s performance.
“For the first time, this study identifies substances capable of reducing hypoglycin A intestinal absorption,” the study team concluded.
“This might have major implications as a preventive measure in cograzers of atypical myopathy-affected horses but also in horses at an early stage of intoxication.”
However, the activated charcoal, which is specially developed for therapeutic use, will not be effective once the toxin has been absorbed through the intestine. Horses are highly unlikely to eat the charcoal directly, meaning it would have to be given through a tube into the stomach by a vet.
The research team are variously affiliated with the University of Veterinary Medicine Hannover Foundation in Halle, Germany; the Leibniz Institute of Plant Biochemistry, also in Halle; and Screening-Labor Hannover, in Hannover, Germany.
Identification of hypoglycin A binding adsorbents as potential preventive measures in co-grazers of atypical myopathy affected horses.
Krägeloh T, Cavalleri JMV, Ziegler J, Sander J, Terhardt M, Breves G, Cehak A.
Equine Vet J. 2018 Mar;50(2):220-227. doi: 10.1111/evj.12723.
The abstract can be read here.