Dr. Galley,
Several years ago I brought you a horse that wouldn’t sweat right when it was really hot. You called him a “non-sweater” and gave me some powder to feed him from April to October every year and it helped him until I sold him three years later. Now I have a horse that can’t stand the heat. He is only 8 years old and he sweats more than any of our other horses during the summer and the other day at a USTRC roping he got what the vet called “heat stroke” and almost went down. Is there any medicine I can feed this one to prevent it?
Answer:
Heat stress in our team roping horses can be a very serious condition that not only limits their usefulness but can lead to death. This time of year we see it quite often because we don’t plan ahead for the conditions that may contribute to it.
The syndrome of heat stress occurs when the thermoregulatory system (the body’s ability to dissipate heat) is not able to keep up with the heat of the body that is produced during exercise. Logic tells us that heat stress will be more common during hot humid weather but I have seen it occur in the winter months in certain situations.
Heat stress syndrome begins with dehydration that can progress to heat exhaustion. As the condition worsens, heat stroke occurs which can ultimately lead to death.
Heat stress occurs most commonly in horses that are not as fit as they should be and are asked to exert maximal effort in hot and humid conditions. This sounds like many of our team roping horses doesn’t it?
First of all, many of us have not been roping as much during the winter so our horses have not been ridden as much and are not as fit as we might have liked. Now that spring is here it is time to crack out and go to some ropings. We hook up to our trailer and load the horses and head down the road early in the morning and as the sun comes up it begins to get hotter. Knowing that it is only another couple of hours to the roping we don’t bother to stop and water the horses or even drop down the doors on the trailer, so when we get to the arena, get our stalls, and unload, the horses are already a little warm and sweaty. We hang a bucket of water in the stall but the horse is too busy looking around and checking out his strange stall to worry about drinking.
We now have about an hour before we rope so we saddle and begin to lope the horses to get them warmed up and by now they are beginning to call for our rotation. The temperature is already getting up into the high 80’s or low 90’s. We cinch up and ride into the arena to rope. The roping started 2 days ago and, after several hundred runs, it feels really hot and humid in the arena. We get our first steer caught and ride back around to get ready for our second steer. It will only be a few more runs before we rope again so there is no need to uncinch so we just wait.
We get by the next steer in good shape. The third round doesn’t take long because a lot of teams have gone out of the average. We get back around in time for our third steer and get him tangled up to make the short round. There is one more rotation so we trot back to the stall, tie our horse up near the water bucket (that now has about 6 inches of water in it), and loosen the cinch and we take off to run back to watch some of the last rotation. By now they are calling the names that made the short round so we hurry back to the stall and tighten up the cinch and head out to lope our horse again so we don’t get turned out in the short round.
We rope a leg in the short round so we have to set there behind the stripping chute while the other teams rope to see if we place in the average with a leg. We glance down at our horse and find the he doesn’t have a dry hair on him anywhere... sweat is just dripping off of him, and he is really breathing hard. We can’t figure out what is going on... we hauled him to the roping in a closed up hot trailer, saddled him up and loped him around, roped four steers in a period of about 45 or 50 minutes in a building that has a high temperature and high humidity... and he is breathing hard and sweating a lot? What could possibly be the cause? Sound like anything that has happened to any of us? Sure has happened to me!
All of us have experienced our horses getting overheated. The heat stress syndrome doesn’t occur until the overheating becomes excessive. Horses cool themselves primarily by sweating. A horse that is exercising to its maximum potential (such as team roping) may sweat as much as 2 to 3 gallons of fluid in an hour. The evaporation resulting from the sweating reduces their elevated body temperature. High humidity makes this evaporative cooling less efficient. High temperature and high humidity combined can lead to serious trouble quickly. Heat stress, also known as heat exhaustion, usually results from protracted fluid and electrolyte loss during this exhaustive exercise. Warm air temperature and high humidity prevent a horse from adequately dissipating internal heat from his body. Around 70% of the heat of maximal exercise is normally dissipated from the body using this process.
A horse suffers both body fluid losses and electrolyte imbalances when sweating. A racehorse which sweats during a mile-long race loses lots of body water and a small amount of electrolytes, but the exertion is quickly over. In a short time, he should easily replenish what was lost. But a horse which exercises in high heat and humidity for several concurrent periods, such as a team roping horse, continues to dehydrate as heat from the continually working muscles is eliminated through sweat and evaporative cooling. This is especially true in heavily muscled horses such as those we rope on. Remember that they are losing not only water but also electrolytes as they sweat.
As the affected horse worsens and progresses toward heat stroke, they may act as if they are trying to tie-up (as you all remember from previous articles, tying-up is known as rhabdomyolosis) and will be reluctant to move when asked to.
They will be breathing heavily and not recovering as quickly as you would expect them to recover. Their heart rate will be quite rapid as will their breathing. Their rectal temperature will rise quickly and often exceed 103 degrees. If the rectal temperature approaches 105 to 107 degrees that is a very serious sign and a veterinarian needs to see this horse right away.
DO NOT try to move the horse very far. Just unsaddle him where he is and begin to hose him off with cool water over his head, neck, and body and especially between his front legs and hind legs. Offer him water and allow him to drink. Horsemen have always believed that an overheated horse should be limited to just a few sips of water but they can have a gallon or a little more at a time.
If you can get a large fan near him then keep it blowing on him to cool him more rapidly. If no fan is available then position him by an entrance door that has some air moving through it.
A horse that has ever tied-up or has experienced heat stress will often be more likely to experience either or both of these conditions again. A horse that has begun to exhibit heat stress or even heat stroke should begin to recover within about 30 to 40 minutes if you have provided drinking water (assuming that he will drink it) and have been hosing him off. If his respiration and heart rate are still very high after 30 minutes then it is time to call your veterinarian. If a horse has experienced severe heat stress or even heat stroke they should not be used again for a minimum of 10 to 14 days.
As far as prevention of heat stress syndrome, it is mostly by exercising common sense. If it is hot when you are hauling him then have maximum ventilation of your trailer with both front and rear dropdowns opened. Stop and offer him water every hour or so. If he is sweaty when you arrive at your destination then go ahead and hose him off to cool him down. Put a fan or two on his stall to keep air moving. Those big box fans are cheap, especially if you can prevent heat stress.
All of your horses should be on a good quality electrolyte powder that can be administered either orally or in the drinking water (or both). These products are cheap and will help prevent any electrolyte imbalances. You should start the electrolyte powder about the first of April and keep them on it daily until the last of October or first part of November. Check with your veterinarian for his/her recommendation.
If you see your horse getting pretty hot and have a couple of rotations between runs then go ahead and unsaddle and hose him off to help him cool off before you need him again. Good horsemanship will pay huge dividends when you are talking about heat stress. If you are entering several times and only have one horse then ask to be split up when you enter. This will allow your horse to cool off a little between runs.
Heat stress and especially heat stroke can be very serious and even deadly. Take them very seriously and do all things possible to prevent them. Thanks for the question and good luck at the ropings.