Throughout history, horses have been able to perform and thrive in very hot, even desert, environments. Breeds such as the Arabian, Akhal-Teke and predecessors like Turkoman and Byerly Turk are among the many desert adapted breeds.
Sand is about as dry and abrasive an environment as you can get. To make things even worse, did you know that dirt or sand will be as much as 40 degrees Fahrenheit hotter than the air temperature? Obviously the success of desert breeds shows it takes more than hot dry weather and surface conditions to cause hoof problems. A further example of hooves’ resistance to heat is that experimentally putting blocks of hoof wall in a 140 degree Fahrenheit (60 C) oven for 2 weeks causes no change in the outer protective permeability barrier.
A major function of the hoof wall is to hold its natural moisture in while sealing excess moisture from the environment out. This is accomplished through incorporation of a variety of fats – fatty acids, waxes, cholesterol and ceramides. Poor quality of this fatty matrix surrounding and covering the cells leads to hoof dryness and cracking.
The horse’s natural protective shield can also be disrupted mechanically. Rasping the dorsal hoof wall is a common practice but it’s asking for trouble, especially in extremely hot and dry weather. The outer few cellular layers are critical to the moisture barrier. Nails from shoes mechanically disrupt the barrier function.
Stress cracks develop from unbalancing trimming or going too long between trims and allowing the hoof to become overgrown. The strength and quality of keratin protein in the horn tubules also influences how easily the hoof wall flares, deforms and cracks as it grows. Whatever the cause, once the integrity of the hoof wall is breached, it will rapidly dehydrate.
The difference between horses whose hooves stay healthy in hot and arid conditions versus those that dry, crack and peel is quite simply the health of the hoof. Research has shown that the function and strength of the barrier fats in the hoof is strongly influenced by the ceramide content. That, in turn, responds to biotin supplementation. The requirement of the horse is unknown but research has shown favorable response to a dose of 20 to 30 mg/day for the average horse.
The horse is capable of synthesizing all the fats needed for the hoof wall with the exception of essential fatty acids. No dietary minimum requirement has been set for fat in the equine diet but supplemental fat often noticeably contributes to coat and hoof quality. Other key nutrients for the hoof wall include the vitamin pyridoxine, essential amino acids methionine and lysine as well as trace minerals.
Topical hoof dressings are no substitute for a healthy hoof but if you find your horse is in trouble they can be helpful while you work toward maximizing hoof nutritional support. Pair glycerin and vegetable oils with penetrating Neatsfoot oil to boost barrier function. Turpentine, Yucca and Aloe Vera may help ease temporary sole tenderness. Iodine and essential oils help support healthy microbial levels and good circulation.
All is not lost if your horse’s hooves become dry and brittle in the heat. Careful attention to sound nutrition and temporary use of a good dressing to boost barrier function can get hoof health back on the right path.
Eleanor Kellon, VMD