A hoof abscess is an infection in the hoof that causes pain and leads to lameness. Horses that have a history of seedy toe (a separation of the hoof wall from the sole) due to chronic lameness are prone to abscesses; however, any horse is susceptible. An abscess is not life threatening; but if not treated, it can become worse and lead to serious hoof problems.
A horse will have a hoof abscess for several reasons. A penetrating injury to the sole of the foot, such as stepping on a nail or any other type of puncture wound can cause an abscess. An infected stone bruise, which occurs when a horse walks on hard ground or steps on a rock, can cause an abscess; and a stone bruise can also emerge if a rock gets wedged between the shoe and the hoof. Deep cracks in the hoof wall, allowing bacteria to enter the inner hoof, will also lead to an abscess.
The most obvious sign of a hoof abscess is severe lameness and your horse may be reluctant to walk or bear weight on the sore foot. Other signs of a hoof abscess are warmness and an elevated digital pulse of the affected foot. To check the digital pulse at the fetlock joint, place your thumb and fingers on the fetlock joint at the back of the leg. Press gently over the cordlike bundle underneath the skin, until a pulse is felt. You will feel a throbbing pulse if it is elevated. If you are uncertain, feel the digital pulse on another leg of the horse for comparison. A normal digital pulse will be faint if you can feel it at all. While checking the digital pulse, you will also be able to feel any warmness in the sore foot.
A group one abscess, or a subsolar abscess, is the result of an infection through the capsule of the hoof, which traps the infection between the epidermis and the dermis. This build-up increases pressure, pain and the spread of infection along the path of least resistance. A group two abscess results when an infection penetrates deeper into the foot structure, which is substantially more serious. A group one abscess that is left untreated can lead to a group two abscess. When an abscess has blown out, pus will discharge from the edges of the sole or frog, the coronary band or from old nail holes. Signs of a group one abscess are black, brown or grey pus and a group two abscess will discharge creamy white or yellow bloody pus.
If an abscessed hoof has not blown out on its own, it must be drained. A veterinarian or a farrier will use a pair of hoof testers to determine where the abscess is and then cut out a small hole to allow the infection to drain. As the pus drains from the abscess, it relieves pressure and pain. After opening the abscess, flush it out with an antiseptic solution such as povidone iodine, and apply a bandage to keep it clean and dry. The hoof will need to be soaked daily in Epsom salts and warm water to help pull out the remaining infection. Soak and bandage the foot daily until the pus no longer comes out while flushing.