Preventing Thermal Injury During Hot Weather

Now that we are almost into the “dog days of summer”, horse owners should pay attention to temperature and humidity while exercising their horses. We will likely experience the highest temperatures of the year over the next couple of months, and the humidity can be pretty high in the Southeast during the summer.

As the horse exercises in hot weather, heat builds up in the core.  Blood flow increases to transport that heat buildup to the surface (skin) where hopefully the heat is dissipated.  One way that horses dissipate heat is through sweating.  Sweat is composed of water and minerals, and helps dissipate heat through evaporation and provides evaporative cooling for the horse.  It goes to reason that the more intense the exercise, the greater the heat buildup, and the greater the loss of fluid to sweating is.

Thermal Injury is caused by animal dehydration.  A horse’s water intake can increase 300% with prolonged exercise, and there is a direct correlation between fluid loss, inability to maintain temperature, and onset of fatigue during endurance exercise.  Too much dehydration leads to electrolyte and pH imbalance, fatigue, uncoordinated gait, and increased risk of orthopedic injury or death.

To minimize the risk of thermal injury during exercise, provide plenty of water, adequate salt and minerals, and a good, balanced ration.  After strenuous exercise, allow horses a 24-hour period to rehydrate between exercise programs.

To further minimize the risk of thermal injury, pay attention to weather conditions.  Knowing the temperature and relative humidity allows us to calculate a “comfort index”.  The comfort index is the sum of the temperature in degrees Fahrenheit and the percent relative humidity.  A total less than 130 indicates that thermal injury should not be a concern.  If the score is between 130 and 150, a horse will sweat, but should not incur serious thermal injury.  If the comfort index is over 150 and the relative humidity is over 75%, heat dissipation can be a problem and horses should be monitored closely during exercise.  If the comfort index is over 180, heat dissipation will likely be a problem and the workout should be discontinued or rescheduled.

Under normal conditions, diet and mineral supplementation, along with adequate water, should be enough to maintain electrolyte balance.  However, with intense exercise programs, the horse will sweat a lot, which can lead to water and electrolyte deficiency.  Symptoms include weakness, muscle cramps, acid-base imbalance, and decreased performance. 

As the horse becomes more acclimated to the exercise level, the heat, and humidity, its mechanisms to conserve sodium and potassium improve.  Horses that are not acclimated to heat and humidity, and that are starting a vigorous exercise program should be monitored closely, and may require electrolyte supplementation to avoid thermal injury.

Much of the information in this article and additional information on the topic of thermal injury is available at http://articles.extension.org/pages/25671/responsible-horse-care-for-winter-and-summer by Steven M. Jones, Extension Horse Specialist.

Think Before You Breed

Breeding your mare for profit or for personal use is a huge undertaking both financially and physically.  If you are thinking about breeding your mare this year, here are a couple of things to consider before the deed is done.  

Once you have decided to breed, you must think of all of the potential cost. Have you prepared for the financial burden that you are about to undertake? There are a few categories to think about when trying to determine the complete cost of breeding.  There is the stud fee which can range between $500 and $5,000 depending on quality of the stud.  Next there are breeding fees, including veterinary fees, semen collection, and shipment if you choose to utilize artificial insemination.  You also have to plan for the total cost of caring for the mare throughout gestation and the cost of the foal after birth. They both will need vaccines, farrier services, and deworming. After that if the foal is for personal use, you will not have to worry about auction or selling fees, but if this foal is for profit that will need to be included in your budget.

After preparing your financial plan, you will need to assess your mare. Does your mare have the ability to get pregnant and maintain a foal throughout the entire gestational period?  To make sure you will need to perform the multi step breeding soundness exam to ensure that her body is fully equipped and healthy enough to safely carry a foal to term.

Once you know that your mare is able to foal, you can start to evaluate what stud is right for your situation. Many people often want to try and breed for color as the first priority.  However,  you should prioritize structural correctness and breeding for soundness to obtain a healthy foal.  Another factor to look for when selecting the stud and a broodmare is temperament.  Temperament is often overlooked, but is an important factor in determining how well your mare will do during pregnancy, and it will be a good indicator of the foal’s temperament as well.  

Consider why you are breeding this particular mare? Is it because you are looking for something specific in a riding horse?  If that is the case then your best option might be to purchase a horse instead.  There are many horses that are of good quality that go unwanted and then possibly fall into the wrong hands and are neglected.  Instead of breeding your mare and bringing another horse into this world, you may be better off saving another.  Chances are it will not be exactly what you are looking for, but it could be close enough, and certainly less costly than breeding.

If you are still set on breeding your mare here are several articles that go into detail about cost and knowing when your mare is ready to be bred.

Financial Success in Breeding:

http://www.horseinfo.com/info/faqs/faqbreedingQ1.html

http://www.horseinfo.com/files/FinancialSuccessinBreedingInstructions.pdf

Breeding Soundness Exam: http://www.thehorse.com/articles/12623/shed-ready-breeding-soundness-exam

Sand and Manure Ingestion

Horses that eat sand or manure normally have a reason for doing so, but figuring out what that reason is and correcting it, can be a challenge.  Horses may eat sand out of boredom, because they are not getting enough grass or hay, or because they have a mineral deficiency.  Bored horses may need some balls or other toys to entertain them.  They also probably need more exercise than they are getting.  Increasing your horses exercise time, may counter some of the sand eating.  They may also learn this behavior from other horses. 

Horses that don’t have enough access to hay or grass, will sometimes eat sand or manure because they are trying to fill their stomach’s.  Increasing intake of what they need to be eating should curb the sand and manure eating by keeping them full.  If the pasture where your horse is located is really short, sometimes they can eat the roots that are covered in sand unintentionally.  Foals that eat manure are normal because of their curious natures, but it can also be helpful for them to ingest bacteria that are healthy for their guts.  However, adult horses eating manure is not normal and an indication of a problem.

It’s good to give horses minerals even if the sand eating is not the reason.  It’s easier for horses to eat a loose mineral because it’s difficult to get enough mineral out of blocks because their tongues are different than cattle.  It should be fed free choice in a bucket or container separate from the feed, so they can eat as much as they need.  It needs to be specific for a horse and not be a trace mineral.  Trace means they are mainly getting salt and not much mineral.  Horses need both.  It needs to be kept out of the weather, so it stays dry.  Once it gets wet and clumpy, horses don’t normally eat it.  If horses don’t eat the mineral you provide, they are probably getting all the vitamins and minerals that they need from their feed.  If you have problems with one or several of your horses eating sand and manure, it’s a good idea to consult with your veterinarian about preventing it, before they end up with colic.

Please read these helpful links for more detailed information:

http://www.thehorse.com/articles/27691/coprophagy-conventional-conduct

https://www.vetary.com/horse/condition/coprophagia

http://www.sand-colic.com/wp/prevention-of-sand-colic/why-do-horses-eat-sand/