The abscess in the horse represents a localized accumulation of pus in a cavity between or in a tissue. This pus consists of dead white blood cells and melted tissue and is well separated from healthy tissue by a capsule. Abscesses can occur in any part of the body.
They can mature acutely quickly, i.e. increase in size, warmth and painfulness, or persist chronically in unchanged form. Furthermore, superficial and deep abscesses are distinguished. These abscesses (also known as nodes) are usually accompanied by inflammation and can be painful due to the increase in pressure. Over time, the abscess can burst and release pus.
Typical symptoms are a soft, flabby swelling, which in its early stage can also feel rough and hard and can sometimes be very painful and warm. It sometimes has a bulbous appearance and the skin can be reddened. Hair may fall out on the surface. The size and spread of abscesses varies greatly. The general condition can, but need not be disturbed, after the pus is drained the symptoms usually disappear more and more.
The causes of an abscess can be manifold. Triggered by a wound or the penetration of a foreign body or an injection into the skin surface. Or also in the hoof due to an injury which can then sometimes lead to lameness.
Abscesses can also affect the organs internally. For example, abscesses in the lymph nodes are caused by bacterial inflammation, such as the bacterium Streptococcus equi, a trigger of the dangerous druse disease (inflammation of the upper respiratory tract of the horse).
In the case of superficial abscesses, the symptoms alone, based on the course of the disease, often indicate the diagnosis of abscess already at the examination. With deep abscesses the diagnosis may be more difficult.
Smaller abscesses are often resorbed (dissolved) by the body. Usually, however, an abscess matures as it increases in size and the tissue finally softens at one point due to the pressure it creates. There, the capsule begins to melt down and finally opens up and empties the pus. If the pus empties (e.g. on the skin) to the outside, healing usually occurs.
However, if it breaks open inwards, even more severe inflammation usually occurs in the neighbouring tissues. If passages form to other tissues through which the pus ultimately drains, a so-called fistula has developed. When an abscess is mature enough, it can also be opened by the veterinarian by splitting it to accelerate healing. The maturation itself can be accelerated beforehand by applying traction ointments. Since chronic abscesses in horses often do not progress in their maturation, it may be necessary to split and scrape them out (curettage).
After opening, the abscess cavity should be kept open long enough, disinfected and rinsed repeatedly to allow the remaining pus to drain. Only then may the wound be allowed to heal.