Foot Abscess

Foot abscesses are a common cause of lameness and can be quite alarming for owners as some horses go severely lame very quickly, which can look as though the horse has broken its leg. Abscesses can be managed relatively easily but if the abscess is not diagnosed and treated early it can lead to long term complications, such as infection of the pedal bone3.

This section of the website will cover the causes of foot abscesses and how they are diagnosed and treated.

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What is a foot abscess?

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 band2.

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 foot1,3. 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 develop2.

Signs of a foot abscess

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.

TYPE OF LAMENESS DESCRIPTION
Mild  Mild lameness may be intermittent, almost unnoticeable or difficult to detect. Mild lameness doesn’t usually cause the horse any obvious anxiety of loss of function.
Moderate Moderate lameness is easily recognised (by an obvious head nod or drop of the pelvis) even if the affected leg can’t be identified. The horse will have some degree of functional impairment.
Severe A severely lame horse will be in obvious discomfort/pain and have difficulty moving the affected leg (hopping lame). It may/may not be weight bearing in that leg and may be reluctant to stand.


 clyde-unwilling-to-bear-weight-on-left-hind-leg-video-thumb.jpg Video: Unwilling to put weight on hind leg

clyde-severely-lame-in-walk-video-thumb.jpgVideo: Severely lame horse

In the healthy horse you can feel a faint digital pulse and the pulse rate should be 25-48 beats per minute.

With the majority of foot abscesses, the pulse rate will be strong and fast but in some cases the pulse rate may be only slightly increased3

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The digital pulse is taken at the point where the digital artery crosses the sesamoid bones.

When you can feel the pulse, you should count the rate for 1 minute

 

  • The abscessed foot may be warmer to the touch than the normal foot2
  • There may be swelling around the pastern, although this is less common2. The swelling can travel higher up the leg, which can sometimes make it look like another condition 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. In cases of mild to moderate lameness, your vet may be happy for a farrier to look at the horse’s foot. However, if the horse is severely lame it should be seen by a veterinary surgeon urgently.

If your vet or farrier suspects a foot abscess, they may 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.

testing-to-locate-abscess-video-thumb.jpg Video: Using hoof testers to locate hoof abscess

 

 

 

 

The white line may also be lightly 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 or farrier can open the abscess to allow the pus to escape (the pus may be grey/black), which will release the pressure and relieve the pain1,2

greb-black-pus-coming-out-of-drainage-hole-in-toe-video-thumb.jpg Video: grey/black pus coming out of drainage hole

 

 

 

 

Treatment

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 clean1. Antibiotics aren’t usually given in the first instance as they tend to seal the abscess, making it more difficult to drain. 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.

To poultice a foot, you will need:

  • Animalintex or similar
  • Sofban bandage
  • Vet wrap
  • Duct tape
  • Clean sterilised bowl
  • Clean hot water
  • Poultice boot (if available)

A hot, wet poultice is applied until pus has stopped coming out of the hole, which usually takes a few days1. Wet dressings aren’t applied for more than a few days as they can weaken the hoof2.

A dry poultice can then be used to protect the foot from reinfection as the abscess will have created a tract up the foot to the deeper structures2.

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 advice1.

Preventing foot abscesses

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 feet3. If your horse is unshod and has suffered repeated foot abscesses, it may be worth speaking to your farrier about shoes.

 

References

  1. Agne, B. (2010) Diagnosis and Treatment of Foot Infections. Journal of Equine Veterinary Science, 30 (9), pp 510-512.
  2. Milner, P.I. (2011) Diagnosis and management of solar penetrations. Equine Veterinary Education, 23 (3) pp. 142 – 147.
  3. Stephenson, R. (2011) Presenting signs of foot abscessation – A practice based survey of 150 cases. Companion Animal, 16, pp. 4-7.