A little more than a year ago, I was invited to travel to Australia to be the keynote speaker at a conference on horses and land management. One of the other speakers at that event presented material that changed some of my thinking on horse care. Dr. Gary Muscatello, a microbiologist and faculty at the University of Sydney Veterinary Science Department, gave a presentation on the link between climate change and infectious disease risk for horses. Let me summarize key points from his presentation.
Connecting the climate change dots with disease
Worldwide, whenever there are new disease outbreaks (human or horse), there seems to be a link between climate change and infectious disease risk. 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. Warmer temperatures enable disease-carrying organisms to extend their ranges, have a longer breeding season, and generally become more virulent. Animals (both domestic and wild) which are already stressed by changes (less water, hotter temps, less food availability, etc.) are now more susceptible to diseases, particularly to new diseases, moving into the areas. This interaction of stressed animals and new pathogens, along with animals which are immunologically naïve, causes new disease outbreaks in horses.
An example in the human world is Lyme disease, which previously did not occur in Canada, but now does. Birds and ticks, the carriers of Lyme disease, never survived in these colder areas but with warmer temperatures they are traveling further North and the pathogens are surviving.
Climate change and equine disease
In Kentucky in 2001, Eastern Tent Caterpillars were found to be the cause of abortions in Thoroughbred mares, called Mare Reproductive Loss Syndrome (MRLS). The caterpillars, when accidentally ingested by pregnant mares, produced abortions. These caterpillars are associated with drought conditions, part of the climate change model. Chronic Obstructive Pulmonary Disease (COPD), which is associated with poor air quality and air pollution (both also part of the climate change model), seems to be on the rise and is expected to continue to increase. Bacterial pneumonia, which has a big impact on foals, lives in soil and is exacerbated by dry, dusty conditions—again associated with climate change. Australia, in particular, has seen huge increases in this disease in their Thoroughbred racing industry, causing economic havoc.
Examples of other types of diseases expected to become more widespread are Pigeon fever, a bacteria spread by midges and biting flies that live and breed in mud, and rain scald or rain rot which is caused by bacteria that thrive in a wet environment, often spread around water tanks or other muddy areas.
Managing the uncertainty
The trends in climate change point to things being much different in the next 10 or 50 years. Worldwide, we are experiencing extreme weather events which were previously in 100 year cycles. Expectations are for droughts and water limitations, extreme weather patterns like monsoonal rain events, more wind, frequent flooding, cyclonic extremes like super hurricanes and super tornados, and generally warmer/dryer temperatures.
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. It means great impacts on agriculture in general with less availability of hay and grain and the associated increases in costs due to greater diseases affecting crops, etc.
What can be done?
Management is key! First, understand disease risks and what can be done to break connections. More than ever, pasture management is important to reduce bare spots and overgrazing so there’s less dust in the summer and no mud in winter. Implement mud management techniques to reduce habitat for disease carrying organisms such as using footing in confinement areas and gutters and downspouts on buildings. Clean waterers regularly to reduce mosquito and insect habitat. Learn and implement water conservation methods at home and on the farm or ranch. Future-proofing us and our horses means taking action to plan and prepare for changes in our climate.
