Dr. Caity Cosentino
Yesterday your horse was perfectly fine. You had a great ride, cooled him out, groomed him and gave him treats. When you left the barn he was happy and healthy, munching hay or grazing out in the field with his friends. This morning you come down to find a crippled horse, who won’t put any weight on one of his legs. Don’t panic! If there is no sign of any trauma or injury your horse is likely afflicted with the dreaded hoof abscess. There are many scenarios in which your horse can develop an abscess (even by simply just being a horse!). An abscess is formed in the foot when bacteria enters the foot (usually through a defect) and gets between the hoof wall or sole and the sensitive laminae lying underneath. Pus builds up in a pocket, and when the pocket becomes large enough pressure builds up to the point where it is extremely painful for the horse to put any pressure on their foot.
Although abscesses are most commonly seen in wet weather (the softening of the foot allows bacteria to enter), they can occur at any time of the year and during any weather conditions. Puncture wounds in the foot, nails too close to the sensitive laminae, cracks in the feet and even bruising to the soles can trigger an abscess to form. Horses who have Cushings disease, or other concurrent illnesses that affect the bodies immune system, are more likely to develop abscesses in their feet.
Once an abscess is suspected there are a few steps that are taken to confirm the diagnosis. The pulses in the lower limbs can be taken. Often times a horse with an abscess will have an alteration in the blood flow to the foot causing a bounding pulse in that leg. The coronary band and heel bulbs will be palpated. An abscess will take the path of least resistance out of the foot and sometimes that means coming out at the coronary band (popping a gravel). Hoof testers can be used to try to pinpoint the location of the abscess and your veterinarian or farrier may try to find the tract where the abscess started and open it up to relieve the pressure. In some cases where it is not evident that an abscess is present, diagnostic nerve blocks and radiographs may be indicated. Remember that even though these signs often indicate the presence of an abscess, there are other more serious causes for significant lameness that need to be ruled out.
Treatment of an abscess centers around relieving the pressure in the foot, cleaning out the pus and keeping the area clean and dry while the defect fills in. If possible your veterinarian will create a hole in the foot to allow good drainage, apply a poultice to draw out the remaining material and apply a bandage to the foot to keep it clean and dry. Often they will prescribe soaking the foot and re-bandaging until the area is healed and hardened. The majority of horses will heal well with no long term effects from the ordeal. If an abscess becomes chronic however, there is a chance that the surrounding tissues and bony structures can be affected and long term damage can be done, resulting in permanent lameness. For this reason, all abscesses should be addressed early and good nursing care should be provided.
Preventing abscesses is not always possible, and if you own a horse long enough, you too will have the pleasure of learning how to effectively bandage a foot (diapers and duct tape will be your friend!). Keeping up with regular foot care with your farrier and cleaning out their feet is critical and your first line of defense. Making sure your horse has a clean, dry place to stand in the rainy season and picking out stalls regularly can also help. Avoiding overly dry and overly wet conditions will reduce the risk of developing an abscess, but even the most conscientious owner will experience this problem from time to time no matter careful they are. When you find yourself standing in the wash stall with your third rubber pan of water with Epsom salt (cause your horse flipped over the last two), just remember it could be worse and all the nightly soakings and bandage changes (where you duct taped yourself to your horses foot) will be worth it when your four legged friend is using all four feet again and you are once again in the saddle!