"Pus Under Pressure"

A hard day at the farm

Pus hissed past me and hit Nancy on her leg three feet away. The mare groaned out loud as she placed weight again on her hoof.

Personally, I love abscesses. My humor as a vet often is misunderstood and when I shout with glee as I discover an abscess, people step away distancing themselves from the strange man. Until, of course, I explain that an abscess is nature’s way of getting bad things inside the body to the outside while protecting the body from being infected. The pus is the white blood cells that have come to the rescue, isolated the foreign object and bacteria, started to digest the material, and take the waste to the outside through a softening through a hole in the skin. It is an effortless miracle of all creatures on earth when you think about it.

Unfortunately, in Nancy’s mare, the white cells were having a problem finding a way out because the abscess they were forming was in the mare’s hoof. These are called sole abscesses and locally they are commonly referred to as “gravel.” They are frequently seen in horses as well as all hoofed animals. I had seen my fair share in my first year of practice working on cattle.

Unusual architecture of an arena roof

When the sole of the hoof gets a break in the surface, dirt and bacteria enter and slowly eat away at the insensitive horny hoof material. When the digestion of hoof reaches the sensitive layers, the horse starts to show signs of pain usually seen as an acute lameness in the limb.

This mare had an unusual case of gravel. The infection had entered near the toe and migrated up the hoof wall toward the coronary band. However, it never hit the sensitive tissue until it had gone half way up the hoof wall. When it finally got there, the pus pocket had grown to a large size but was constrained within the unyielding hard hoof wall. The pressure continued to build causing the horse great pain. She had gone from a mild lameness to non-weight bearing in about a day.

I took an X-ray and I could see the black hole of an abscess half way up the front of the hoof wall. I called in the farrier and asked him to bring his drill. We were going to drill through the wall into the pocket to relieve the pressure and provide a way out for the pus.

There were two problems. First, the mare was too painful. Just placing my finger on the front of the hoof sent the mare rearing straight up. Second, the farrier thought I was nuts.

I sedated the mare and then I injected the lower part of the leg with a local anesthetic. This effectively removed all sense of pain from the leg. Then I showed the farrier where to drill and he grumbled how when this went all wrong, it would be my fault and that he was just following orders. He slowly drilled at right angles to the hoof wall until we reached blood.

The beautiful courtyard of a Florida barn

The farrier gave me that look of “I told you it wouldn’t work.” The mare stood quietly and the owner asked, “Well?” I pointed to a spot about 1/2 inch to the side of the first hole suggesting the new drill location and the farrier reluctantly started to drill again.

When the bit hit the pocket, a small dribble of pus oozed around the sides. The drill was removed and immediately the pus shot out of the hole and continued for a full 5 seconds landing on Nancy’s leg. The look of shock on her face as she screamed, “Oh my God!” was replaced by the horse with the numb leg actually groaning and sinking her full weight back on the limb.

Opinions of me changed that day. My position in life rose (for about a day) in the farrier’s mind. Nancy became a client forever. Most interestingly, the mare who had been reluctant about needles and everything else veterinary, became a long time friend. Our future barn visits always started with the mare giving me a nuzzling of thanks.