Z.W. – VA

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With the Washington Metro area just closing the books on the hottest month ever recorded, what is and isn’t safe for us and our horses has been a serious topic.

Running a boarding stable for the past 13 years, one curiosity I’ve noticed pretty consistently is the number of calls from concerned boarders we receive about their horses’ health and comfort in the winter, but the lack of calls even when we are posting heat indices of 120 or more.

It was explained to me by our vet many years ago like this.  A thousand pound animal with an inch of fur is made for staying warm, but can have a lot of trouble keeping cool when the weather turns hot.

Heat and humidity are combined to produce what is called a “Heat Index” or what it “feels” like outside.  In climates with very low humidity a 95 degree day may actually only produce a heat index of 90 or even 85.  Crank up the humidity, though, and you can experience what we did here in the Mid-Atlantic; 95-100 degree days with heat indices of 115, 120, or even like I saw just two weeks ago, 125!  There’s a simple term for this kind of weather – Killing Heat!

In animals that cool through perspiration, the cooling process is dependent on the rapid evaporation of sweat.  As the air becomes more and more saturated with moisture, it can’t readily accept any more, thus no evaporation and no cooling.  Couple this with the fact that for most horses under saddle, a large portion of their evaporation area is covered with a saddle and pad and you’ve got a recipe for an animal that can get very, very hot, very, very fast, and can only cool very little or not at all.  Core temperature can rise in minutes to a dangerous level and no amount of simple rest will allow for enough cooling to reverse the process.

For some general rules of thumb we are going to assume a horse in average body condition that works between 2 and 5 hours a week (the average trail horse.)  You can adjust these guidelines for horses in better or poorer condition.

Through heat indices up to 90 degrees, horses can exercise normally.  From 90 – 100 begin limiting exercise to shorter bursts of trot and canter and longer cooling walks.  Try to stick to the shade when you can.  Between 100 and 105, short walks with little or no trotting and stick close to home in case you need to get you or your horse under a hose.  After 105 I’d avoid anything more strenuous for your horse than grooming or grazing.  This would be a great time to re-watch those Parelli DVD’s you’ve been meaning to get back to.

If you have ventured out, here are some signs that it is time to get your horse cooled out.  If your horse is breathing harder than normal for the activity level, or beginning to pant, or his nostrils are flaring very rapidly, and it doesn’t return to a more appropriate rate in 1 minute.  If your horse is no longer sweating he’s probably already reaching a dangerous temp, and if he/she begins to exhibit a stilted gate, lethargy or any seeming confusion you are in the beginning of a heat stroke and need to get that horse under a hose, possibly packed with ice wraps around major arteries and should be calling a vet.  Your horse may likely require IV fluids at this point.  This exact situation just occurred a couple of weeks ago at a Civil War reenactment that went forward despite a heat index of 110.

Do not fall into the myth that you shouldn’t hose a hot horse.  Remove the hose nozzle and hose the horse quickly from head to toe, spend a little extra time on his back, chest, neck and belly, then concentrate your hose on the major arteries inside the hind legs.  This will allow you to cool the greatest amount of blood in the least amount of time and hopefully drop his core temp before any major organs, including the brain, are affected.  If someone can get a second hose, continue hosing the back, neck, chest and belly.  DO NOT give electrolyte paste to a horse in this condition.  Electrolytes must be accompanied by plenty of fresh water or they will actually pull water from the blood into the gut.  Electrolytes are a great way to pre-condition your horse to hydrate in advance of a ride and also a wonderful way to disguise foreign water when away from home so that your horse will continue to drink, and electrolyte flavored water to can be offered to a horse in heat exhaustion, but NEVER administer a paste.

Heat exhaustion and heat stroke can occur in a horse startlingly fast and can be hard to get back under control.  Take it seriously, and pay attention not just to temps, but to humidity and the heat index.  When in doubt, sit it out.  Before you know it we’ll be talking about winter riding!

Keep it Natural,

Todd