November 24, 2016

Do Adhesives Used on the Equine Hoof Trap Moisture?

Many people ask if the acrylic and urethane adhesives currently used on horse’s feet trap moisture resulting in adverse effects.  The answer should be no, but it’s not always that simple.

Before we can answer the bigger question, we must first understand the importance of moisture.  The equine foot naturally contains moisture generated internally from blood circulation; it keeps tissues pliable for shock absorption.  Obviously the environment also plays a huge role in maintaining moisture balance.   Dry environments dehydrate, harden and shrink the structures of the hoof, while wet environments soften, swell, and expand the hoof.  Both can have detrimental effects.  Aside from specific environmental factors, such as frequent bathing, seasonal changes can wreak havoc with feet, especially in those environments that experience quick changes from wet to dry and dry to wet.  Feet that shrink and swell repeatedly require more frequent care.

There are specific numbers associated with correct hoof moisture levels, but they are of little use to the owner and hoof care practitioner.  All we can do is determine from inspection if the hoof is too dry or too wet; fortunately, that is not too difficult.  What is harder to determine is what to do about it, and how often it needs to be done. 

Dry hooves can be hydrated simply by allowing the horse to stand in a wet environment for a short period, however, there is a big difference between relatively “clean” wet, and a wet area saturated with manure, urine, and therefore, bacteria and fungus.  Wet hooves can be harder to dry out if the horse cannot be separated from a wet environment.  Traditionally, hot fitting shoes was a good method for sealing hoof wall tubules to minimize absorption of excess moisture.  This practice is still used today, especially in the performance world where horses are bathed excessively. 

The equine market is flooded with all types of dressings and coatings that supply moisture, hold moisture in to keep it from evaporating, and/or seal out excess moisture.  For the average horse owner, wading through these products and their claims can be money well spent or money wasted. 

So when we apply adhesives to feet, there is a lot to consider: the current condition of the hoof, the condition of the environment, the activity level of the horse, hoof care regiment, and especially, a clean, dry place to do the application.

Whether gluing on shoes, making repairs, corrective extensions, or pour-in urethane pads, preparation is critical to success.  As with any adhesive, the instructions require a clean, dry surface, not always an easy task but doable.  Achieving cleanliness ranges from a good wire brushing to debridement, removal of unattached structure, and disinfection.  Drying is achieved by use of a heat gun or portable propane torch held a few inches from the surface to be dried, for perhaps a minute or two.  Although the idea of using a torch on a horse’s foot sounds alarming to some owners, when used properly, it is a superior drying tool that can also be used to kill bacteria quickly without heating up the foot.  With careful and proper preparation, adhesive applications should last weeks, or at least the cycle between trims/shoeing.

Once properly applied, adhesives do limit evaporation of moisture since they create a barrier similar to the hoof capsule itself; that can be a good thing.  In moist environments, adhesive applications can also prevent intrusion of excess moisture. Wet environments, however, can compromise the bond and trap moisture behind the application.  Adhesive applications are generally contraindicated as a barrier to wet environments because it is almost impossible to keep them bonded, and if they remain in place, can harbor moisture and pathogens.  If a horse will be standing in a wet, muddy paddock, it is often a waste of time and money to attempt adhesive applications in the first place.

The bottom line is, adhesives can be very effective for protecting and restoring the function of a hoof, and when properly applied under the right conditions, do not trap moisture.