And horses are just as prone to heat-induced issues as any animal, so a few precautionary steps can stave off trouble, according to Dr. Samantha Morello of the UW-Madison School of Veterinary Medicine.
When the weather turns hot, a series of events can cause a horse to suffer, Morello said. First in the series is water consumption. Heat can affect behavior, causing the horse to not drink as much as it should to keep up with water loss on a hot day.
"Losing body water can then create sub-clinical dehydration," Morello said. "The large intestine has to reabsorb extra water from the ingesta, which then becomes too dry to move easily. This can lead to an impaction of the large colon."
Impaction can set the horse up for mild colic. Symptoms include no longer passing feces, pawing, a distended belly, going off feed and laying down. Most of the time a horse will recover with proper veterinary care.
"Your veterinarian will do an exam including a rectal exam to find out if there's an impaction," she said. "Treatment usually involves fluids. A nasogastric tube, which is a hose into the stomach through the nose, can deliver fluids and/or mineral oil to help break up the impaction."
Only in extreme cases does a horse need intravenous fluids, pain medication and sedation.
Recovery from a bout of heat-induced colic requires gradually reintroducing high quality hay and pasture grass. Walk the animal frequently.
Total access to clean, fresh, cool water is essential, Morello said. Clean, cool and fresh water means maintaining water tanks and buckets. Clean the waterers routinely so they don't accumulate dirt, algae and old, foul water.
Change the water frequently. Do everything you can to encourage your horses to drink water. Access to salt and mineral blocks also helps horses maintain a good balance of electrolytes.
Pasture horses should have a shady place, whether it's a run-in building or trees. Turn on fans and add fans near stalls for horses that are in stables. Good fly and insect control also helps reduce exertion on hot days.
"Fresh pasture grass also is an excellent natural laxative," Morello said. "The grass has high water content and is readily digested and is better than hay in hot weather."
Feeding high quality hay also helps. Quality hay means the material is high in feed value and easily digested as opposed to a hay that's perhaps harvested late or has been rained on during harvest. It's a matter of keeping the horse's body working normally during a period of stress.
"When it comes to heat, think about the things you do for yourself at those times. If you're going to exercise, do it in the cooler part of the day. It's probably not good to take a hard lesson at 2:30 in the afternoon on a hot day," Morello said.
Riding indoors in a well-ventilated arena may help if you're riding in the middle of a hot spell. If you have to move horses by trailer, make sure to have all of the windows open for ventilation. If you're going on a long trailer trip, plan for frequent stops to water and move the horses around.
In general, keep the anxiety and stress levels to a minimum during hot spells for both you and your horses.