June 29, 2023

Sweatless Summers: Unraveling the Mystery of Anhidrosis in Horses!

Picture this: it's summertime in Georgia, the sun is blazing, and horses are feeling the heat. But for some equine pals, their sweat glands decide to take a vacation, leaving them high and dry. This puzzling condition, known as anhidrosis, occurs when horses can't produce enough sweat to cool down. Horses affected by anhidrosis are often referred to as "non-sweaters." This condition not only limits their performance but also puts them at risk of overheating or experiencing heat stroke.

So, what causes this sweat-less saga?

Although the exact cause of anhidrosis remains a bit of a mystery, experts believe it involves an overwhelming stimulation of the horse's sweat glands by stress hormones, particularly during the scorching summer months. It's like the sweat glands go on strike, leaving our four-legged friends vulnerable to overheating and potential heat stroke.

Horse drinking from a hose

How do you spot anhidrosis in action?

Anhidrosis can vary in severity from horse to horse. Some may experience subtle signs, such as a decrease in sweat production, while others endure a complete shutdown of their sweat system, resulting in severe hyperthermia (that's a fancy term for overheating). It's often performance horses who bear the brunt, but non-performance horses aren't immune either, especially those with darker coats.

Look out for clues like decreased performance as the temperature rises, an elevated respiratory rate, and a slow return to normal body temperature after exercise. A lackluster or dry-looking coat and lethargy during the hotter months may also raise suspicions. Has your horse started seeking shade or trying to get into the water trough? Those may also be clues.
Note: Normal Horse Temperature is between 99.5 to 101 degrees Fahrenheit. Exercise can elevate their temperature, but it should return to normal within 30 minutes after exercise cessation.

Making a Formal Diagnosis:
A more formal Diagnosis of Anhidrosis involves a combination of observation, veterinary examination, and specific tests. If you suspect your horse might be a "non-sweater," it's time to bring in the expert—your veterinarian, who will observe your horse's behavior, performance, and physical signs. He or she might perform a series of injections using dilutions of terbutaline, a substance that stimulates the sweat glands. This helps identify if there are any issues with sweating and determines the severity of anhidrosis. Your vet may also do some blood work including an electrolyte analysis. This helps paint a clearer picture of your horse's overall health and can provide valuable insights for formulating a treatment plan.

"Unfortunately there is no known cure for the disease. It's all about managing and/or treating the symptoms to make the horse as comfortable as possible," shares Dr. Dan Carter.

Treatment Options for Anhidrosis:

Treating anhidrosis can be a perplexing puzzle for horse owners, but there are options available to manage this condition and keep our equine friends comfortable. What works for one horse may not work for another.  Moving the horse to a cooler climate is the only known successful approach, but this may not always be feasible. So, how can owners effectively care for "non-sweaters" in hot weather? Let's explore some strategies and considerations.

Horse under a misting fan.
Creating a Cool Haven:

To prevent high body temperatures, it's important to provide a suitable environment for non-sweaters. Consider night turn out. Stall them or keep them in shaded paddocks during the day to help minimize heat exposure. Install fans, misters, or sprinklers in their living space to provide much-needed relief. Some horses might even take the initiative to cool off by stepping into troughs or ponds in their pastures.

"Installing the misting fan in Cole's stall has made the biggest difference from anything I have tried. It's at least 20 degrees cooler in there. Thank you for that recommendation." shared one Countryside client. When purchasing a misting fan, ensure it is high pressure, the most effective cooling for hot and humid areas such as Georgia.

Exercise safely:

Ride during the coolest hours of the day, either early morning or late in the evening. Hose your horse down with cold water before starting exercise and bring a bucket of cold water to reapply during your ride. Always scrape off excess water which, if not removed can trap heat. Give lots of breaks during your ride, leave plenty of cool down time after exercise and monitor respiration rate. Hosing their neck, legs, and body with cold water and putting them in front of a fan will help bring down the body temperature post ride. Always keep an eye out for any sign of heat distress.

Hydration is Key:

Ensure constant access to cool and clean drinking water. Non-sweaters may require extra attention to maintaining appropriate electrolyte concentrations. Supplementing their diet with electrolytes or salt mixtures, such as "Lite Salt," can aid in electrolyte balance and hydration.

Anhidrosis supplements
The Supplement Conundrum:

It's essential to approach claims of relief from various supplements with caution. While many manufacturers boast about their products' efficacy, the evidence supporting their effectiveness is mostly anecdotal. Treatments involving dark beers, salts, vitamins/electrolytes, or thyroid hormones lack substantial scientific backing, but some clients have seen improvements from supplements. Some popular supplements on the market for Anhidrosis are One AC, Platinum Refresh and Kentucky Equine Research Restore SR.

Alternative Therapies: Acupuncture

Alternative therapies like acupuncture and herbal treatments have helped some anhidrotic horses. A recent study performed at the University of Florida found that acupuncture and herbal medication may have improved sweating in recently anhidrotic horses, although the effect lasted less than four weeks after discontinuing treatment. The use of this treatment requires further investigation to fully validate its usefulness, as that study yielded very equivocal findings. Countryside's Dr. Zoe Lattimer is a certified Equine acupuncturist. Reach out if you would like to discuss acupuncture for your horse, or request an appointment online.

The Pursuit of Effective Treatments:

Researchers continue to delve into the causes and treatments of anhidrosis, aiming to unlock better solutions for affected horses. The current understanding points to a signaling mechanism at the sweat glands' level as the root of this disorder. Scientists have also observed irreversible changes in the sweat glands of chronically anhidrotic horses. This ongoing research holds promise for improving the treatment of anhidrosis in the future.

It's important to approach medical treatments cautiously, as some have shown limited success and carry potential risks. While we await further advancements in treating anhidrosis, it's vital to stay informed, rely on evidence-based approaches, and work closely with your veterinarian to develop the best management plan for your horse.