How rising temperatures and extreme weather events are affecting horse keeping, and what you can do to reduce their negative effects

For many horse owners, the mention of climate change might conjure up images of melting glaciers and super storms—events seemingly far removed from their charming little farms. However, because agriculture depends on natural resources and weather conditions, it is often cited as the sector most vulnerable to the effects of climate change.  

With weather patterns already changing, horse keepers and equine professionals are noticing differences in quality and availability of pasture, hay, feed, bedding, and other agricultural products. Additional climate change factors that might affect horse owners include spread of new diseases, emergence of new weed species in pastures, expanding geographical ranges for crop pests, and higher fuel costs, which influence product availability and purchases as well as horse hauling.

But the news isn’t all bad. Practices that horse owners currently embrace, such as rotational grazing, might offer big-picture solutions for dealing with climate change. However, developing new practices or adapting old ones sometimes requires thinking outside the box, balancing innovation with tradition.  

Seeing the Changes

Climate change trends point to weather patterns continuing to evolve over the next 10 to 50 years. Worldwide, we’ve already experienced multiple recent extreme weather events previously seen only once every 100 years. Droughts and water limitations are more widespread, such as what’s happening in California, parts of Texas, and the Southwest. So are extreme weather patterns like the super snow events the East Coast has experienced in recent years; monsoonal rain; high winds; frequent flooding; and cyclonic extremes. In North America super storms Ivan, Katrina, and Sandy might jump to mind.

These changes mean “disease-carrying insects and pathogens will be flung further along by strong winds and have broader ranges that are more habitable for them,” explains Gary Muscatello, BVSc, GradCertUnivTeach, PhD, a microbiologist and academic at the University of Sydney Faculty of Veterinary Science. It also means greater impacts on agriculture in general with less availability of hay and grain and the associated increases in costs due to crop diseases, etc.  

Climate Change and Disease  

In 2012 I was invited to Australia as the keynote speaker for a national conference on horses and land management. Muscatello was one of the speakers at the event, and he presented material that changed the way I think about climate change and horse management—specifically the link between climate change and infectious disease risk for horses.

Muscatello presented information associating some recent worldwide disease outbreaks (human and horse) with climate change. “The general principles of a warmer environment and changing weather patterns influence many factors, which encourage disease outbreaks, disease transmission, and the emergence of new diseases,” he explains. Beyond extending ranges for pathogens and their carriers, warmer temperatures mean “the disease-causing pathogens themselves replicate at a higher rate, and subsequently can potentially generate more virulent, novel strains.”  

Animals, both domestic and wild, that are already stressed by changes (less water and food available, hotter temperatures, etc.) can become even more susceptible to diseases—particularly new ones—moving into geographical areas. “This interaction of stressed animals and new pathogens,” Muscatello says, “along with animals which are immunologically naive, causes new disease outbreaks.”

He uses an example from the human world, Lyme disease, which prior to the 1990s did not occur in much of Canada, but now does. Colder regions of the country were uninhabitable for birds and ticks, the carriers of Lyme disease, Muscatello says. “But now with warmer temperatures birds and the ticks they carry are traveling further north, with ticks and their accompanied bacteria surviving and thriving in Southern Canada even during the winter period.”

He also describes the caterpillar-associated abortions seen in Kentucky in 2001 and in Australia in the mid-2000s. In Kentucky, Eastern tent caterpillars were found to have caused abortions in Thoroughbred mares, called mare reproductive loss syndrome (MRLS). Similarly, caterpillars in Australia were linked to a syndrome called equine amnionitis and fetal loss (EAFL).  

“In both cases, caterpillars, specifically their hairs (setae), which were accidentally ingested by pregnant mares, produced abortions,” says Muscatello. “The risk of exposure to caterpillars and their hairs increases during dry and windy periods seen during droughts or extreme weather events, part of the climate change model.”  

Another example in horses is recurrent airway obstruction (RAO), which researchers believe has been on the rise in horses over the past 20 years, says Muscatello. Commonly called heaves among horse owners, RAO is a chronic lung disease that produces clinical signs ranging from coughing and wheezing to reduced performance and difficulty breathing. It’s associated with poor air quality, such as dust and air pollution—again, part of 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 Rhodococcus 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 treatment 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. Consequently, Australia’s Rural Industries Research and Development Corporation has put a significant amount of funding into studying this disease.

While researching R. equi, Muscatello “began to realize the relationship between 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,” Muscatello 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 proliferates, 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 appropriate pasture management practices is probably the single most import component to preventing or counteracting some of the effects of climate change on our horses. Turning out smaller groups of horses reduces pasture traffic and prevents 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 speakers, Carlos Saviani, vice president of the World Wildlife Fund’s U.S. food team, described new opportunities for sustainable 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 -contribute to climate change as well as impact livestock health, he says.

Sandra M. Matheson, DVM, a lifelong farmer, traveling educator, filmmaker, author, and retired veterinarian who lives and ranches in Bellingham, Washington, helps put this in perspective. One of her areas of expertise is pasture management, for which she offers a holistic perspective that includes balancing natural resources, people, and finances.  

“Traditionally, agriculture has been a huge contributor to climate issues,” she explains. Overgrazed pastures and bare soils not only lead to dust and mud stressors for livestock, but they also cause soil erosion, scorched organics in the soil, and hotter ground—dark, bare ground absorbs heat from the sun that grass cover would otherwise utilize and reflect.  

“By planning our grazing, we can put animals in pasture areas for appropriate amounts of time, so that we are not beating up the ground,” she continues. “Then we can reduce dust and mud and manage the pasture in a way that produces good-quality forage (for grazing). Animals … will have less stress and fewer predispositions to diseases. Plus, if we can improve the health and biodiversity of grasslands then we are able to sequester more carbon.”  

Simply put, plants help clean the air. Industrial emissions, automobile exhaust, and burning of any sort put a tremendous amount of carbon into the air. Researchers report that carbon and those gases contribute to changing global temperatures. “The idea of sequestering carbon in active growing plants is a better long-term way to take in carbon from the atmosphere,” Matheson explains. “When you have a lot of bare ground there is not much carbon being captured from the air. When you have grasslands covered with plants, the plants are continuing to pull carbon from the air and move them into the roots and soil where it is stored.”  

These management strategies are just a few simple ways horse owners with their own acreage can help reduce the effects of climate change, as well as keep their horses healthier.  

Taking Action

Preparing for future climate change means planning now. Here are some simple management techniques you can implement on any horse property to reduce your impact on the planet and keep your horses healthier.

Reduce mud in paddocks:

• Install rain gutters and roof runoff systems on all barns, sheds, and outbuildings to divert the clean rainwater away from high-traffic areas. This will reduce the amount of nutrients from manure and urine and sediments from soil that wash into surface waters, degrading water quality and destroying the aquatic environment. It will also reduce the amount of winter mud in your paddocks.
• Use a footing material, such as coarse washed sand or crushed rock, in paddocks to help reduce soil erosion and mud problems during the rainy season.

Improve pastures:

• Create a sacrifice area or paddock to keep your pastures from becoming overgrazed, particularly during winter. Using a sacrifice area also confines manure and urine to an area where you can manage it more easily. Surround this area with a grassy buffer, such as lawn or pasture, to act as a filter for contaminated runoff.
• Cross-fence pastures and rotate horses between sections to prevent overgrazing and soil compaction. Horses are particularly hard on pastures; the pounding of hooves compacts soil and suffocates plant roots. In pastures, at least 3 inches of leafy material is needed for rapid regrowth and biofiltration of nutrients, sediments, and chemicals. Poor pasture management results in reduced grass quality and quantity and increased soil erosion, nitrogen runoff from manure and urine, and weed proliferation. It also increases feed costs because of the reduced pasture productivity and potentially increases veterinary bills if your horse eats toxic weeds.
• In the winter, keep horses off rain-soaked soils and dormant or frozen pasture plants to preserve a healthy pasture for next summer. Soggy soils and dormant plants simply cannot survive continuous grazing and trampling in winter months. When the soils are wet, horse hooves act like plungers by loosening fine particles of topsoil that are then washed away by rain.

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 removing 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 directions 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 possible, 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.

Take-Home Message

Managing horses in the face of climate change involves preparing for the variety of disease risks researchers say it can pose. Implement mud management techniques, such as placing footing in confinement areas and installing gutters and downspouts on buildings, to reduce disease-carrying organisms’ habitats. Clean waterers, buckets, and troughs regularly to reduce mosquito and insect breeding grounds. Learn and apply water conservation methods at home as well as on the farm. But above all, manage pastures so they are grassy and do not develop bare spots.