Anhidrosis In Horses

Thankfully for the majority of horse owners anhidrosis is a condition they will never have to worry about. However, if you keep your horse in a hot and especially a hot humid climate it is a condition that you should educate yourself about as being able to identify it is vital to your horse’s well-being. 

Anhidrosis is a condition where horses either stop sweating or reduce the amount of sweat that they create. Since sweat production is their major way of cooling and maintaining their ideal body temperature, any reduction in this ability to sweat leaves them at risk of overheating and can be fatal. Owners managing horses in hotter climates should pay attention to their horse’s sweat patterns. Some horses may sweat under their saddles when worked but be unable to sweat on their necks. Or sweat patterns may be patchy. 

Horses that are unable to sweat adequately will have elevated heart rates and respiratory rates which is one reason why it is unsafe to work horses with anhidrosis if they are not sweating adequately. Therefore, the condition has major performance implications. While it generally impacts working horses, sedentary horses can develop the condition as well. In climates where it is so hot that horses sweat standing around this can be extremely challenging.

Some horses suffer from anhidrosis every summer while others may have historically been just fine or have been fine through the start of the summer and then suddenly stop sweating. For this reason, it cannot be assumed that just because your horse is sweating fine now, that he will continue to do so throughout the summer. 

Frustratingly the condition is that it is not very well understood. It appears to be more prevalent in darker colored horses and research has found that up to 20 percent of racehorses training in Florida become non-sweaters. However, our knowledge is improving. Horses have a sweat gland at the base of each hair follicle. Adrenaline stimulates the sweat gland to produce sweat. Historically veterinarians have considered the condition to be the result of an overstimulation of the sweat gland due to too much adrenaline.

More recent research at the University of Florida has found patterns within families of horses with certain breeds being more susceptible. On closer investigation an area of the equine genome using a Genome Wide Association Study suggests an area of the genome may be responsible for anhidrosis. Specifically, a region containing the KCNE4 gene. Sequence analysis shows a single nucleotide variation in a base pair of genes in the DNA sequence that may alter the KCNE4 protein function. The relevance of KCNE4 is that it codes for a portion of a potassium channel that may impact the outflow of sweat from the sweat gland. This means that anhidrosis is likely hereditary. Therefore, it is currently recommended not to breed horses that have anhidrosis. 

While it may be possible to genetically select against anhidrosis in the future this is of little help to people currently trying to actively manage horses with the condition. There are no research proven methods for preventing the condition from starting or to reinitiate sweating in a horse that has become a non-sweater. However, there are some practices that anecdotally may help. 

Ensuring adequate salt and electrolyte intake is important for all horses but may help to prevent the onset of anhidrosis in some horses. All horses should be fed 1 tbsp of salt per 500 pounds of bodyweight everyday of the year to ensure that their maintenance sodium requirements are being met. In hot weather this can be doubled, or a commercial electrolyte should be added. Such an electrolyte should have chloride or salt as the first ingredient. Salt block or free choice loose salt should also be provided. 

Some owners report good luck using B vitamins, dark beer or yeast supplements. Yeast is a rich source of B vitamins and dark beer is a source of yeast. Others use vitamin C or tyrosine even though research on these found no conclusive evidence that they work. 

Here at O3 Animal Health, we receive many positive reviews about the success of our Mega Sweat supplement. This product is designed to be administered short term (no more than 2 weeks), and to jolt the adrenal system back into function. In the case of particularly resistant individuals, it may be combined with Oxy Cleanse which provides a combination of Himalayan Sea Salt as an electrolyte with Acai Berry, a potent antioxidant.

Regardless of the supplement support systems tried, horses with anhidrosis should be kept in areas where they have access to fans and misters and if they can be worked, they should be exercised early in the day when the temperatures are the lowest. For horses that are unable to regain the ability to sweat and that suffer from the condition annually it may be necessary for them to move and live in a cooler area. 

Our Mega Sweat product has special dosing instructions. For the average sized horse, we suggest you feed 4 to 5 pumps/oz of the Mega Sweat twice daily. If you are using the Oxy Cleanse powder, you will sprinkle one half cup over the top of the Mega Sweat.

You will go through one gallon in approximately two weeks. If the horse begins to sweat normally within that time, finish the gallon and the suggested dose and then immediately move the horse onto the Equine Omega Complete product ongoing. 

If you have questions please feel free to get in touch with us. (855) 366-8822