Abscesses are usually caused by a bacterial infection which is localized at a certain point in the body. Dead white blood cells and bacterial matter create a build up of pus, which creates pressure. Abscesses in the hoof are especially painful, because the hoof capsule is a restricted environment – there’s little room for expansion, especially between the hoof wall and the coffin bone. To heal, abscesses need to break out to the surface of the body and drain, and they’ll follow the path of least resistance to get out. If an abscess isn’t able to break open and drain, the infection can become more widespread.
If your horse has a hoof abscess, your veterinarian is likely to recommend using a poultice to draw out infection. A poultice is a soft, moist mass that is applied to the hoof under a bandage, which can be purchased or homemade, using a variety of medicated, or natural ingredients.
Commercially-available products contain an anti-septic and a poulticing agent, such as tragacanth, a sap-like plant material, on a ready-to-use pad. You soak the pad in warm water, apply the poultice directly to the bottom of the foot, and bandage it in place. You can also use a homemade poultice such as a paste made from sugar and iodine or Betadine® solution. Sugar is osmotic, which means it will draw infection out. Iodine/Betadine® is added as a disinfectant. Another popular homemade poultice combines two parts wheat bran, one part Epsom salts and enough water to moisten the mixture.
A hot poultice applied to the bottom of the foot will soften the sole and encourage the abscess to break. After the abscess has broken, you want to keep the wound open to continue draining. If the wound closes over at the surface, but infection is still present inside, these are perfect conditions for an abscess to occur or re-occur. Poultices keep the opening moist and encourage drainage.
Changing bandages daily is recommended, as a poultice can dry the foot out if the abscess hasn’t broken. Soaking the hoof in warm water and Epsom salts (two cups to a gallon) between bandage changes is also a good practice.
When the abscess bursts, the pus will come out, but the open wound then needs to fill with granulation tissue, which takes about three to four days. Once the granulation tissue is in place you don’t need to bandage anymore.
Abscesses in Other Places
A hot pack may be used for abscesses in other areas of the body. Causes of abscesses in other areas of the body include Strangles and muscle injections or puncture wounds that have become infected and healed over at the surface. A hot pack application opens up the blood vessels in the area, increasing blood flow and leading to an increase in local inflammation, which helps encourage the abscess to open and drain. You shouldn’t use the same osmotic material directly on the surface of the skin, as you would with the hoof sole, because skin is more tender and it could cause irritation.
For a hot pack, you can put bran or mashed potatoes in a resealable plastic bag and warm it up in the microwave (not too long). Wrap the bag in a towel and bandage it against the area of the abscess. You don’t want to use anything hot directly against the skin. You can also purchase a hot/cold gel pack, the same as for humans.
Poultice vs Antibiotics
With foot abscesses and Strangles, a poultice is preferred over the use of antibiotics for several reasons. First, because you always want to be cautious to not over-use antibiotics – it’s always best to let the horse’s immune system do its job when it’s capable of doing so. Second, the use of antibiotics is contra-indicated in many instances of abscess, unless it’s accompanied by a life-threatening condition such as pneumonia. Antibiotics can cause a capsule to form around the abscess, creating a pocket of bacteria which may promote antibiotic resistance. In the case of strangles especially, the bacterium Streptococcus equi subspecies equi (Strep. equi) can travel to other places in the body and create new abscesses (called bastard Strangles).
You want an abscess to drain – that’s the primary goal for treatment. A poultice is the most effective means to do so.