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
52 TheHorse.com THE HORSE August 2015 Horse chestnuts and buckeyes The horse chestnut tree and the buckeye ap- pear similar and are in the same genus, but the horse chestnut is not as hardy or tall and features leaves divided into seven smaller leaflets. Their seeds are said to resemble a buck's eye, and their leaves are green in summer, turning golden and orange in the fall. These trees are moderately to highly toxic in horses, says Williams. Poisonous parts include leaves, seeds, and young sprouts. Poisoning is more common in spring due to early sprouting, and clinical signs of poisoning include gastrointesti- nal irritation and neurologic signs. Holly tree or shrub The American holly, recognized by its evergreen prickly leaves and red berries, is moderately toxic to horses. Clinical signs after ingestion can include digestive upset or colic, leading to tremors or seizures in severe cases, says Williams. Toxic parts include but are not limited to the berries. Other potentially lethal trees and shrubs include the golden chain tree (Laburnum anagyroides), chokecherry (Prunus spp), Kentucky coffee tree (Gymnocladus dioicus), Russian olive (Elaeagnus angustifolia), and persimmon (Diospyros virginiana). Incorporating Trees on Your Farm Safely Before you go chopping down every tree in your horse's field, know that hav- ing a horse farm with plenty of shade- giving, aesthetically pleasing, safe trees is possible. There are many nontoxic trees for farms—too many to list, says Williams. First, eliminate any toxic trees and shrubs, or at least the most lethal ones, like seed-bearing female box elders. If this is not possible, avoid turning horses out in fields containing these trees (or with them nearby) during the fall or early spring when seed burdens are high. After you have cut down toxic trees, dispose of them properly (e.g., not within horses' reach). Next, realize that just because the trees were cut down does not mean they are gone for good. All hardwood trees, includ- ing oak and maple, will sprout from the stump. Some, such as black locust, will sprout from the lateral roots (which leave the tree at the ground line), says Jeffrey Stringer, Extension specialist in the Uni- versity of Kentucky's forestry department. So what are you do? Grind out the stumps or use herbicides, he says. Typi- cally, the latter involves applying 80-100% strength herbicides to the freshly cut stump. For large stumps, you only need to spray the 3 to 5 inches from the inside edge of the bark toward the center. Fence Off and Monitor If you want to keep the problem trees on your property, use strategic fencing and monitor trees to ensure branches and leaves do not fall in the pastures. The distance you fence around the tree is pri- marily based on what part of the plant is problematic, says Stringer. If the bark is the problem and not the leaves, place the fence four to five feet from the tree trunk. However, the problematic compo- nents of most toxic trees are the leaves and seeds. From that standpoint, horses should be kept—at a minimum—from under the tree's drip line (the outermost circumference of its canopy, which inevi- tably gets larger as the tree grows). While windblown leaves that fall to the ground might float into pastures and paddocks, these dried leaves often are not problematic. It's avoiding the green or wilting stages of leaves that is critical. By keeping horses from under the drip line, you help ensure that they can't easily ac- cess broken limbs that hold wilting leaves. Educate Yourself Many Extension offices offer tree and shrub guides. If you need help identifying a tree, bring samples to your local Exten- sion office, or check out this online tree identification tool from Virginia Tech: dendro.cnre.vt.edu/ dendrology/idit.htm. Further, the University of Idaho has devel- oped a database of plants toxic to equids that you can access here: webpages. uidaho.edu/range/toxicplants_horses/ Toxic%20Plant%20Database.html. h EQUINOMICS ABOUT THE AUTHOR Maureen Blaney Flietner is a freelance writer, photographer, and designer who has owned and cared for horses for more than 30 years on her Wisconsin farmette. MAUREEN BLANEY FLIETNER Eliminate lethal trees growing near where horses are stabled or turned out. Plant and Protect There are reasons beyond toxins to keep horses away from trees. Pasturing horses right next to any tree—even benign—can wound the lateral roots. The wounds allow internal rot to develop. Horse movement around trees also compacts the soil surface, which Stringer says can lead to tree decline and earlier tree mortality. If you don't fence off your trees, then check their condition regularly or have an arbor- ist evaluate them. Assess branch junctions to determine which ones might be at risk for breaking. (Bad for the tree and also dangerous for horses below it!) Large limbs weakened by rubbing, storm damage, or poor pruning develop weak spots that might give way under pressure from wind or ice. Decay can cause a branch to break at its collar, and even healthy large horizontal limbs can collapse under stress. Branches with cavities, cankers, and conks, also known as shelf fungi, indicate internal decay and should be pruned because they are at risk of breaking. Without fencing, horses might strip the bark off trees in pastures or paddocks. If horses girdle the tree (remove the bark from around the entire circumference of either a branch or trunk), they can kill it.—Maureen Blaney Flietner