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.
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21 August 2015 THE HORSE TheHorse.com the climate change model—and might also be a consequence of more frequent indoor housing of horses during extreme weather events. For Muscatello, what brought the climate change and equine health link into focus was his doctoral thesis on Rho- dococcus equi, a type of bacterium that causes bronchial pneumonia in young horses. R. equi is one of the most important infectious diseases of foals worldwide, affecting as many as 10% of this equine demographic in some countries and costing owners in endemic regions millions of dollars annually in treat- ment costs. The disease is a significant concern to stakeholders in the Australian Thoroughbred breeding industry, where increasing R. equi prevalence is affecting the quality and quantity of future racing Thoroughbreds—a huge concern to a nation whose racing industry contributes AU$8 billion to its economy. Consequent- ly, Australia's Rural Industries Research and Development Corporation has put a significant amount of funding into study- ing this disease. While researching R. equi, Muscatello "began to realize the relationship be- tween the ecology of the organism and farm management." Using a tool that measures air hygiene, he took readings of the air just above the soil surface in Thoroughbred breeding farm pastures and paddocks. Drier, dusty areas, such as overgrazed pastures, sandy paddocks, or holding areas for mares and foals, had more airborne R. equi than did healthy fields. "The bacterium has a coprophilic (manure-loving)-soil life cycle," Mus- catello explains. "So when you have an environment highly contaminated with fecal material, plus a lot of animals, and it's dry and dusty, Rhodococcus equi pro- liferates, becomes airborne, and is spread to more foals," which become infected through inhalation. Global temperature increases accelerate development of dry, dusty environments. Muscatello cites examples of other diseases becoming or expected to become more widespread: pigeon fever, caused by a bacterium midges and biting flies that live and breed in muddy conditions spread; and rain scald, often called rain rot, which is caused by bacteria that thrive in wet environments. Alas, that dust that kicks up in the dry, summer months equates to mud in the winter rainy season. What Can Be Done? Here's where we come in. Adopting ap- propriate pasture management practices is probably the single most import com- ponent to preventing or counteracting some of the effects of climate change on our horses. Turning out smaller groups of horses reduces pasture traffic and pre- vents overgrazing and bare spots, which translates to less dust (and aerosolized bacteria) and fewer bugs in the summer. This can reduce pathogen transmission to horses and the inevitable development of mud. Good manure management is another important practice. Pick up manure at least every three or four days and compost it. Get it out of the high-traffic confinement areas where dust and mud form. But, even across the many types of agriculture, the recurrring theme is pastures: In the fall of 2014 I attended the Sustainable Agriculture Symposium in Nampa, Idaho. One of the key speak- ers, Carlos Saviani, vice president of the World Wildlife Fund's U.S. food team, described new opportunities for sustain- able farming. The facts he shared were impressive: 30% of the earth is used as pasture for livestock. Of this, 70% is overgrazed and degraded, which can Implement a manure management program: ■ Pick up manure in all confinement and high-traffic areas regularly. Stockpile manure away from ditches or bodies of water, and consider constructing a composting system. Compost is a rich soil amendment that improves pasture productivity, making grasses healthier and better able to hold moisture. ■ Cover manure storage areas to prevent winter rainwater from leaching nitrogen from the manure pile and taking it to waterways. Use a tarp or plastic sheet to cover your manure pile. Protect valuable surface water: ■ Limit horse and livestock access to ditches, creeks, lakes, wetlands, and other bodies of water. Horses and other livestock tend to trample vegetation along slopes and wet areas. Trees, shrubs, and undergrowth are nature's system for filtering contaminants from runoff. They also help prevent soil erosion and provide food and shelter for fish and other aquatic wildlife. ■ Plant a buffer of native grasses or other vegetation along ditches, creeks, and water bodies. This helps stabilize stream banks, prevents soil erosion, and filters out nutrients and sediments. ■ Reduce chemical use. Minimize herbicide applications, especially near surface water, by remov- ing weeds through mechanical methods rather than with chemicals. When you do decide to use herbicides, be sure to choose the right product for the targeted weed. Your conservation district, Extension agent, or county weed control agency can help you identify your weed, choose the appropriate herbicide, and determine the best time of year to apply it. Spot spray following manufacturer directions instead of broadly spraying a large area. Always read and follow direc- tions carefully, and avoid spraying on windy days or when rain is in the forecast. ■ Keep fill, especially manure and garbage, out of ditches, wetlands, and bodies of water. Conserve water use: ■ Water landscaping and pastures efficiently. When pos- sible, water at night or early morning when it will not evaporate as quickly. Use drip irrigation, microsprays, or soaker hoses wherever possible to apply water directly to the soil with minimal evaporation or runoff. ■ Install automatic waterers, which only use as much water as your horse can drink. Look for systems with moderate-sized water pans—a large one will quickly get dirty and algae-ridden requiring you to clean and dump it frequently. The circulating water also won't provide a habitat for potentially disease-carrying mosquitoes. —Alayne Blickle Sacrifce areas (top) help keep horses and livestock from destroying pastures. Plant native grasses or other vegetation along bodies of water (left) to prevent erosion and flter out harmful nutrients and sediments. COURTESY UNIVERSITY OF KENTUCKY COLLEGE OF AGRICULTURE, FOOD, AND ENVIRONMENT