The Horse:Your Guide To Equine Health Care provides monthly equine health care information to horse owners, breeders, veterinarians, barn/farm managers, trainer/riding instructors, and others involved in the hands-on care of the horse.
Issue link: https://thehorse.epubxp.com/i/539428
50 TheHorse.com THE HORSE August 2015 C arol Elster McCleary's 4-year-old gelding, Pico, remained in the barn one Friday evening in October 2011 while his three pasturemates—his dam and another mare and gelding— wandered out to graze. The pinto fox trotter was eating and drinking normally, but McCleary thought it was odd that he did not join the others. The next morning, with a sinking feeling in her stomach, she found Pico lying in the pasture, but he got up when she approached. McCleary, who lives in Shorewood, Minnesota, contacted her veterinarian, who treated Pico for colic that morning and again in the evening when his condi- tion did not improve. Sunday morning, McCleary again called the veterinarian, who this time suggested Pico had devel- oped laminitis. But when McCleary saw blood in Pico's urine, she immediately knew something else was going on and took the horse to the University of Minne- sota veterinary hospital, 90 minutes away. Shortly after arrival and admission, her beloved Pico, whom she had owned since he was born, went down in the stall. Try as he might, he never rose again. The clinicians tested and diagnosed him with pasture myopathy. Something in his turn- out area at home had poisoned him. McCleary took her other horses off the pasture, had them tested for pasture myopathy with negative results, and asked Stephanie Valberg, PhD, DVM, director of the University of Minnesota Equine Cen- ter, to investigate her property to find the toxic culprit. Several months later, Valberg discovered the cause: box elder seeds. "I removed all box elder trees in and near my pasture to the tune of $10,000," says McCleary. She also had the pasture vacuumed to remove any seeds. It was not until the following June that she put her horses back in the pasture. McCleary says fellow horse owners need to be aware of the dangers of toxic trees, warning that poisoning from box elder seeds "is a terrible death." Here our sources will describe toxic trees and shrubs to avoid so none of your horses end up like Pico. Different Toxins, Different Signs Toxic trees and shrubs cause a variety of clinical signs when horses ingest them. Some are respiratory, some cardiac, some neurologic, and some gastrointestinal, says Carey Williams, PhD, associate pro- fessor at Rutgers' Equine Science Center, in New Brunswick, New Jersey. If an owner sees any signs of trouble, he or she needs to call a veterinarian immediately. "Some toxicities are severe enough that, even if caught early, it might be too late by the time the veterinarian arrives," says Williams. Other toxicities cause problems that don't lead to death. The degree of danger a poisonous plant poses is a function of the plant's preva- lence, toxicity, and palatability. Palat- ability is the key, though, says Williams. Some horses might find one plant more palatable than others, consume more of it, and then get sick. If good-quality forage is plentiful, horses will avoid most poisonous plants because they are unpalatable and have a bitter taste and/or smell. But during periods of drought or when pastures are overgrazed, animals might begin to Wild Cherry WIKIMEDIA COMMONS Red Maple Japanese Yew ISTOCK.COM PHOTOS EQUINOMICS MAUREEN BLANEY FLIETNER TheHorse.com/Equinomics Managing Toxic Trees on Horse Farms Some trees can kill horses, and horses can kill trees; make sure the equine-arbor relationship on your farm is a positive one MAUREEN BLANEY FLIETNER Seeds from box elder trees, such as the one seen here, can cause a deadly muscle disease in horses.