Summer is the season for horse shows… and also for extremely hot and humid weather. Making sure your equine partner is comfortable during summer hauling and horse showing will make for a more successful show season.

Your number one priority should be to make sure that your horse has access to clean, fresh water on a regular basis. A horse is nearly 70 percent water – in an average 1,200-pound show horse, that is nearly 100 gallons of water. That percentage takes into account the amount of water in the bloodstream, muscles, skin, other internal organs, urine and the water component in the horse’s feces.

Recognizing that many show horses are tied up during the work day at horse show, they should be given access at regular intervals to water during the show day. Depriving horses of water can cause many serious health issues, a couple of the most serious being impaction colics and electrolyte imbalances. Impaction colics are most commonly caused by systemic dehydration – the horse will not allow as much fluid to flow into the intestines and into the feces, which makes the feces become much harder and drier, and it becomes more likely to become impacted in the small intestines or large colons of the horse.

Most horses are not picky about the water they drink, and will drink readily if they are thirsty and are given access. You may have one of those picky drinkers who is fussy about the taste of his water, or you may come across a show that has highly chlorinated water or well water with an odd smell or taste.  At some fairground locations, you may be able to located a filtered water system in the barns used for dairy cattle (they prefer filtered water for milk production). You may also need to bring water from home in potable water containers, or buy water at a grocery store.

Adding electrolytes or flavors (like gelatin powder or molasses) should be practiced at home before you get to the show. It is best to stick with the same electrolyte or flavor at all times so that your horse is used to the flavor and smell. It is also a good idea to have a bucket of plain water as well as the flavored or electrolyte water for the horse as well.

Along the same theme, if your horse is not used to getting electrolytes in paste form, or is not drinking well at a show, then using a paste electrolyte at the show for the first time is not a good idea because it can unbalance the electrolytes in the bloodstream and potentially make dehydration worse. Along the same theme, if you have a horse that is HYPP N/H or H/H, the excessive potassium in some paste electrolyte preparations may be enough to cause an attack.

While at a show, if you feel your horse is not drinking well or is excessively dehydrated, having a veterinarian attend to the horse quickly is your best bet for preventing any major problems. One of the most cost effective and quick ways to provide fluid to a dehydrated horse is via nasogastric tube – a water bucket of clean, cool water, maybe with some electrolytes added, can make a huge difference in the hydration of a horse. Veterinarians will also use IV fluids as well, but be aware that it can take 15 to 20L (three to four of the large bags of IV fluids) to effectively rehydrate a horse.

Water is also essential in keeping a horse sweating effectively. Sweat is mostly water, with some electrolytes mixed in as well. Keeping air circulating on the horse’s skin with box fans attached to stall fronts will also help to reduce body temperature. Cool water baths at frequent intervals also help to keep a horse cool. Focusing your cool water bath on areas like the jugular vein grooves on either side of the neck, the lower legs and the upper insides between the hind legs – where major blood vessels are close to the surface of the skin – helps to cool a horse faster.

Anhydrosis is a phenomenon in some horses that can cause them to stop sweating. The physiological mechanism behind anhydrosis is poor understood, and many factors will be at play. A horse that has sweated effectively in the past may stop sweating at the drop of a hat, perhaps when hauled to a location where the weather is extremely hot or humid.

What we do know about anhydrosis is that horses that stop sweating have to compensate by “blowing off the heat,” or breathing very quickly and deeply, using their abdominal muscles, and with nostrils flared, while the hair coat remains perfectly dry. A horse who suddenly appears to be afflicted with anhydrosis should not have any forced exercise, and should have emergency cooling measures instituted immediately – access to fresh cool water to drink, frequent cool water or alcohol baths, along with standing in the shade, preferably in front of a fan. Ice boots may also be applied for short periods. Rectal temperatures should be obtained at regular intervals to ensure the horse is staying at a reasonable body temperature that is not setting the horse up for other issues, like laminitis.

There are also several medications and supplements that have been tried to manage anhydrosis, like ACTH Gel, clenbuterol liquid, niacin powders, or very dark beer poured over feed, but every horse seems to be an individual case and what works for some cases will not work for others. Some horses will spontaneously begin to start sweating again as quickly as they stopped, while others may never regain their ability to sweat effectively, which may limit their ability to continue to be show horses.

Tanis MacDonald Walker, DVM graduated from the Atlantic Veterinary College on Prince Edward Island and currently practices both small animal emergency and equine medicine in Delaware. You can email her at tanis_macdonald@hotmail.com or visit her at www.drtanis.com. You can also write to her in care of InStride Edition.