By Jane King BVet Med MRCVS
A foot abscess, also known as ‘pus in the foot’, is an infection in the hoof. Bacteria enter the hoof through the sole, which leads to the development of an abscess (pus). The hoof capsule can’t expand and the pus puts pressure on the sensitive tissues within the foot as it accumulates, causing pain and lameness. The pain will continue until the pressure is released when the abscess bursts, usually through the sole of the foot but occasionally through the coronary band.
Foot abscesses are commonly seen around the white line area where foreign bodies such as grit penetrate the white line, allowing bacteria to enter the foot. Abscesses can also occur on the sole secondary to bruising of the foot, for example if the horse stands on a flint. Blood from the bruise can carry bacteria and cause an abscess to develop.
Foot abscesses can sometimes be confused with other conditions but the following section will talk you through the most common signs of a foot abscess.
The horse will usually appear severely lame very quickly and may be unwilling to put weight on the leg. However, some horses may only appear mildly or moderately lame. It is also not uncommon for a horse to go lame and come sound, only to go lame again three to four days later, with the lameness getting progressively worse.
The abscessed foot may be warmer to the touch than the normal foot.
There may be swelling around the pastern, although this is less common. The swelling can travel higher up the leg, which can sometimes make it look like an other condition such as tendonitis and cellulitis and confuse the diagnosis.
If you suspect your horse has a foot abscess, you should contact your vet for advice on the best course of action. If we suspect a foot abscess, the vet will use hoof testers to try and pin point the location of the abscess. An increased reaction to hoof testers will help to locate any part of the foot that may be sensitive or painful; this is done by applying pressure with the hoof testers from heel to toe. If your horse is shod, the shoe may need to be removed.
The white line may also be pared using a hoof knife to identify any tracts that could indicate the location of the abscess. Once the location of the abscess is known, the vet can open the abscess to allow the pus to escape (the pus may be grey/black), which will release the pressure and relieve the pain.
Once a hole has been created, treatment of foot abscesses mainly revolves around draining the pus from the foot and keeping the hole in the foot clean. Antibiotics are rarely necessary to treat a foot abscess . If your horse is not up-to-date with his/her tetanus vaccination you should let your vet know, as the abscess hole provides a perfect site for tetanus to enter. Your vet will advise you on the best treatment regime for your horse but it usually involves poulticing the foot to soften the horn and draw out the infection. See page X for further information on poulticing.
Specialist shoes or treatment plates may be necessary in certain conditions, such as when the abscess has penetrated the sole, but your vet or farrier will advise you if this is necessary.
If the lameness hasn’t improved within 2-3 days, or pus continues to drain from the hole for longer than this, you should contact your vet for further advice.
Recent research has shown that unshod horses are at greater risk of developing a foot abscess than shod horses, possibly because shoes give a greater degree of protection to the toe region. The fore feet were also more commonly affected than the hind feet. If your horse is unshod and has suffered repeated foot abscesses, it may be worth speaking to your farrier about shoes.