06/24/2025
📢🚩Anhidrosis Alert! 📢🚩
We had FIVE new cases of anhidrosis (non-sweating) in our patients, just today! This brutal heat is really hard on the horses, and it’s important to know the signs, symptoms, treatments, and management strategies for this potentially brutal equine condition- especially if you live in the South!
🥵Symptoms:
The first sign a horse owner often notices is a “panting” breathing pattern in warm or hot weather. Anhidrosis can occur suddenly or can happen gradually over time. When the condition happens gradually, owners may not notice the early stages, when sweat is still often present under the mane, under the saddle, and between the hind legs. We don’t know exactly why horses stop sweating, but it does seem to occur more commonly in horses that were previously “good” or “excessive” sweaters. It’s likely that the sweat glands become “exhausted” or “desensitized” in these horses.
Horses with anhidrosis can become repeat-offenders and experience this condition every summer. In the most severe cases, the horses never regain the ability to sweat, and can experience heat stress/stroke, dry skin, hair loss, decreased appetite, decreased water consumption, and significantly compromised quality of life.
💉Diagnosis:
Diagnosis of anhidrosis is often made simply by observing symptoms (rapid breathing) in combination with absent or decreased sweating. In cases in which the diagnosis is unclear (horses without a history of anhidrosis in previous years, horses with partial sweating), or if we want to assess the horse’s prognosis for recovery, we can perform a “sweat test.” This test involves injection of very small amounts of a sweat-stimulating medication into the skin of the neck, and observing for sweat from the areas within 20-30 minutes. Failure to sweat at any of the injection sites is associated with a more poor prognosis, and the horse may prove more difficult to treat. The more sites sweat, the better the prognosis.
🩹Treatment:
There is no perfect treatment for anhidrosis, and owners typically need to quickly implement several changes to decrease the chances of this becoming a severe, lifelong condition.
Treatment options include:
• Commercial supplements for sweating (Platinum Refresh and One AC): These are usually the first thing we recommend for horses with anhidrosis. These can be purchased online, and sometimes need to be given at a different dose than what’s on the label.
• Acupuncture: Many horses respond very well to acupuncture treatment for anhidrosis. Some horses begin sweating again within a day of the first treatment, but some will take 3+ treatments to see effect. Treatments are usually performed every 1-2 weeks.
• Lutalyse injection: This hormone injection, typically used in the breeding of mares, causes sweating as a side-effect. This injection can be given to mares, geldings, or stallions to produce sweating. Administering this medication can work as a diagnostic and a potential treatment. If the horse doesn’t sweat following administration, the condition is considered more severe. Some horses may experience cramping, or mild signs of colic with this injection. This medication needs to be administered by, or under supervision of a veterinarian.
• Dark beer: Giving a single dark beer (typically a stout) in the horse’s feed daily has long been recommended for anhidrosis. No one has any idea why this would work, and in our experience it’s not as effective as other potential treatments, but it doesn’t hurt anything, and some horses like it!
• Coffee grounds: Another older remedy for anhidrosis is coffee grounds added to the horse’s feed daily. There’s no specific amount, and yet again, no idea why this would work, but it also doesn’t hurt anything!
💦Management of horses with Anhidrosis:
It is critical to use many different management strategies to keep horses with anhidrosis from overheating, and to reduce the possibility that the condition becomes severe and untreatable.
All horses should have a commercial electrolyte supplement added to their feed, or administered via syringe, daily. Look for an electrolyte supplement with potassium and calcium as well as salt. If your horse has metabolic concerns, please be mindful of sugar!
Horses with anhidrosis should be kept cool as much as possible. They should be hosed off frequently during hot weather and all work/exercise should be avoided. Mister fans are very helpful for these horses, and they can be commercially purchased or constructed D-I-Y.
🚫Prevention:
Once your horse has had an episode of anhidrosis, it is more likely that they will experience this condition again. Taking care to implement multiple strategies in the spring, before hot weather arrives, offers the best chance of success for prevention of severe, recurrent anhidrosis. Starting management and supplements around March here in NC seems to have the best results.
If you notice your horse “panting” or lethargic this week (or in any hot weather), and you think they may have anhidrosis, please call us (or your vet if its not us)!
