by Tamara Scully
Climate change has the potential to dramatically impact anyone raising livestock. Horse owners, too, will need tools to recognize and alleviate equine discomfort as a result of changes in temperature. As heat or cold events become more frequent, and extremes in temperatures are seen, equine owners need to know how to protect their horses.
“They’re not food or fiber. They are agriculture. So they have some different issues, and their physiology is quite a bit different than other livestock animals,” Dr. Cary Williams, Equine Extension Specialist, Rutgers University, said in a recent presentation “Climate Change and the Horse Industry.”
The thermoneutral range for horses depends on the climate to which they are acclimated. For horses unaccustomed to cold weather, 41 degrees Fahrenheit is about the lower limit of this range. For those raised in cold environments, a mere five degrees Fahrenheit is acceptable. The upper limit, too, has a climate-dependent range, from 68 to 86 degrees Fahrenheit, Williams said.
The condition and age of the horse, as well as the amount of exercise it is doing, will impact the thermoneutral range. Knowing what the signs of heat or cold stress are for horses is crucial when caring for these animals.
The normal equine response to heat is to sweat. Along with sweating, increased respiratory rate and an increased heart rate will occur. Their blood moves closer to the skin as capillaries are opened. Whether exercising or not, horses will show these responses when they need to cool down.
Horses do not have an evaporation system, which other animals use to cool themselves down, so anhidrosis occurs under heat stress conditions. The horses will sweat less, or stop sweating, and the skin will become hot and dry.
The heart rate will increase to 50 or more beats per minute — up from the normal 24-40, and the resting respiration rate will become rapid, up to 20 or more breaths each minute. The rectal temperature, normally ranging from 98.5 -101.5 degrees Fahrenheit, will become elevated.
Electrolytes are extremely important to horses under heat stress conditions. Electrolyte solutions should have sodium chloride as the primary ingredient.
“They don’t need to replace electrolytes when they are actually sweating,” Dr. Williams said.
Providing shelter with plenty of ventilation is important during heat stress conditions. Misting fans, which “provide water, and then provide a way of evaporation,” are recommended, she said.
Horses must be cooled down after exercise. Cold water, which can have ice added to it if the temperature are really hot, should be used. Water for drinking is also important, and horses should be given small, frequent sips of cold water, which will help to cool their systems from inside.
Obese horses have more difficulty with thermoregulation. When the weather is hot, increase energy in the diet by adding fat, not carbohydrates. Decreasing the amount of grain and increasing forage in the equine diet will help to keep the weight off, too.
If snow is melting on a horse’s back, the horse is cold. If snow forms and stays on the back, the horse is within its thermoneutral zone and is fine. Horses will use energy to shiver in an attempt to keep warm. They require 2 pounds of energy for every 10 degrees below the low temperature of their thermoneutral range. Thinner horses, or those that have been clipped, should be provided with blankets.
Precondition horses for cold weather. When cold hits, feed free choice grass hay, and provide shelter — such as tree lines, a three-sided barn, or blankets.
Cold season pasture forages aren’t going to perform well if days grow hot and dry, and producers will need to find alternatives for both grazing and haymaking. Common forages of Kentucky bluegrass and orchard grass won’t thrive in the heat.
“Crabgrass loves the warm weather,” and is an option for pasture grazing, Dr. Williams said. It will spread and fill in bare spots in the soil.
If there isn’t enough pasture to graze, or to make a last cutting of hay, producers will need to opt for alternatives. Bagged feed, beet pulp, bran, and rice hulls are all options for supplementing pasture and hay.
Beet pulp is “easily digestible for the horses,” Dr. Williams said, while rice hulls provide a good source of fiber. Small amounts of wheat or rice bran are okay as a supplement, and bagged feed offers a consistent nutritional content.
When feeding a complete feed, horses often still have a need to chew, despite all of their nutritional needs having been met. Feeding forage in combination with these feeds will prevent chewing concerns. Otherwise, horses tend to chew on wood, and can easily chew on toxic plants or other undesirable things that can cause harm.
Climate change will impact feeding strategies, and bring about changes in temperatures that can cause heat or cold stress. Horses may not be acclimated to temperature extremes, and climate change has the potential to cause major changes in weather patterns, causing heat or cold stress.
Dr. Williams left producers with one word of caution, and of wisdom: “Just because you are cold, it doesn’t mean your horse is cold.”
Knowing the signs and symptoms of heat stress, or of being cold, is the first step responsible horse owners need to take to adjust to temperature changes caused by climate change.
Equines and climate change
by Tamara Scully