Equestrian Life,  Holistic Wellness

Anhidrosis and Your Horse: Managing Symptoms

Ah, summer. The beautiful lush grass and extended daylight lead to more time in the saddle and with your favorite equine. But when your horse has anhidrosis or “no sweat”, summer can be deadly. Here are the symptoms to watch for and help with your horse.

What is Anhidrosis?

Anhidrosis in Horses

Anhidrosis refers to the inability to sweat properly and can affect certain areas of the body, or the entire horse. Commonly referred to as “no sweat” in equestrian circles, your horse may be mildly affected or severely affected resulting in the potential for heatstroke.

Horses cool themselves by sweating so when the ability to do so is compromised, exercise or high heat and humidity can result in heatstroke and even death.

Breeds such as warmbloods and thoroughbreds are more prone; however, there is no proven reason behind this as yet.

The Symptoms of Anhidrosis

Symptoms of “no sweat” can be chronic or acute. In temperature or cooler climates, the environment helps to cool your animal and often cases are few and far between. However, in areas such as Florida or even in New Jersey, the summers become hot and humid. This summer has had extended days with the heat index in the triple digits, making it too difficult for horse and rider.

No Sweat in Horses

My pony Ferrous has had anhidrosis in the past and it was something of which I was aware, especially in our first summer together. In preparation for the warmer months, I began him on the One AC supplement in May.

We started well and as the weather began to warm he sweated normally. This did not last, however, as the heat became prevalent with a break I noticed that he had sweat marks under only his saddle pad and girth.

Then the other day, Ferrous appeared lethargic. He refused to walk or trot in the outdoor ring, and he’s never been that lazy. So I walked him inside into the indoor and we had a light workout with walk, trot, canter. I was profusely sweating but he didn’t have a mark on him. No sweat AT ALL.

Alarm bells went off in my head. I immediately hosed him down, wiped off the excess water, and placed him in his stall with the fan.

His symptoms progressed and were quite common:

  • Dry coat.
  • Thinning hair.
  • Heaving, breathing heavily after exercise.
  • Limited sweating especially when compared to other horses.
  • Sweating only in the girth or saddle area.
  • No sweating at all.
  • Lack of drinking.

During the month of July, we took mild walks in the woods together while pony camp progressed and it wasn’t until we started using the ring again that I really noticed how affected he was.


Treating Anhidrosis

Common treatments for anhidrosis may include but are not limited to acupuncture, supplements, and Guinness. Yes, dark beer is a very popular solution for horses with anhidrosis, which even Boyd Martin uses. As he notes in Practical Horseman Magazine,  “Boyd credits daily beer and a nutritional supplement along with a new fitness program for getting Oscar on track to win at the 2014 Red Hills International CIC*** and hit the optimum time at the Rolex Kentucky Three-Day Event this spring.”



Acupuncture is the ancient Chinese tradition of placing small needles at critical energy points to remove blockages. According to DePaolo Equine Concepts, “Chinese medicine believes that anhidrosis is associated with an energy blockage in the spleen and lungs. Using acupuncture points to treat anhidrosis may encourage the nervous system to cause the sweat glands to increase in size and production.”


I’m a huge believer in acupuncture and Ferrous loves working with my partner, Dr. Michelle Morges. Often, he’ll stand and sleep while he’s being treated.



There are a host of nutritional supplements designed to help your horse sweat like they should. Choices can be hard to make. My own horse has been on the top-rated One AC since May but it hasn’t helped like I had hoped. That is not to say that it wouldn’t help your horse. Our temperature index has been in the triple digits for weeks, which is not helping our situation.

Some nutritional supplements are designed to be used for several weeks or months, while others are meant to jumpstart the adrenal system and boost sweating with 24 hours. A Google search results in quite a list.

While I haven’t tried them yet, I’m interested in the Equiwinner Patches, and wondering if they might help during the summer months.


Dark Beer

Dark beers, especially, Guinness have long been recommended in the horse world for horses with anhidrosis. Boyd Martin, of course, is a believer, and Zenyatta drank Guinness as well. Containing important B vitamins, such as thiamin, riboflavin, niacin, pantothenic acid, biotin, folic acid, B6. and B12 are necessary for correct functioning of metabolic pathways.

Additionally, yeast strains like Saccharomyces cerevisiae may often be found in equine pre- and probiotic supplements as yeast are thought to help stabilize the hindgut environment.



Worried about your horse getting drunk? Don’t be. According to The Horse, “As to getting drunk, horses have large amounts of alcohol dehydrogenase enzyme in their livers to process the by-products of microbial fermentation and therefore are surprisingly capable of metabolizing the alcohol present in the beer. Additionally, their large body size means that they’d have to drink substantial amounts of beer before any risk of intoxication.”

While there are a number of treatment options available, none of them are scientifically proven to help. The American Association of Equine Practitioners (AAEP) has noted:

“Many supplement manufacturers claim their products offer relief, but this is anecdotal at best, and no research supports efficacy. Owners use many other treatments with minimal scientific evidence, including dark beers, salts, vitamins/electrolytes or thyroid hormones. Most of these are not dangerous, but they also do not appear to improve anhidrosis when evaluated critically. Researchers have studied acupuncture and herbal treatments using a blinded clinical trial; response was minimal and short-lasting.” American Association of Equine Practitioners.


According to science no treatments or permanent solutions are available, and yet equestrians continue to go with what they believe helps. Ferrous worsened on a supplement alone, even when ridden early in the morning, and cooled down immediately after. I introduced Guinness to his feed recently and I’m hoping this helps. Certainly, it can’t hurt and if it is good enough for Boyd Martin, then it is good enough for me.


Managing Anhidrosis

While there are no proven treatments for no sweat in horses, there are ways to manage the symptoms and keep your horse as cool as possible.

  • Turnout at night.
  • Stall during the day.
  • Fan.
  • Baths/ Hosing Down.
  • Light exercise.
  • Essential Oils like peppermint or a specialty blend administered topically with a carrier oil can help to cool your horse and bring relief while increasing circulation.
  • Moving to a cooler climate.


Ferrous will have paddock time in the evenings and stall rest during the day while I’m away in Mongolia at The Gobi Desert Cup. He’ll be under the watchful eye of my trainer and barn owner, who love him just as I do. I’ll do my best not to worry but it will be hard.

My pony and I do not approve of summer. We are looking forward to autumn and a break from the heat.


Do you have experience with anhidrosis? What has worked for you?




  • Carla Calvo

    I just found your website, I have a horse with the same condition, and live in a tropical country, so Its a though one for me, how did the guiness work for him.

    • Heather Wallace

      The tropics are tough on horses with anhidrosis, since it’s the prolonged humidity that tends to spark it. Guinness does help a bit. I give it to him primarily in the hotter months but he gets Platinum Refresh by Platinum Performance year round. He still struggles, but it definitely helps.

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