Management of chronic and nonhealing wounds

Nonhealing wounds are a particular concern in horses because of the relative tension of the skin and lack of underlying soft tissues on the lower limbs. Thus, any wound at or below the carpus or tarsus is immediately problematic because of difficulties ensuring primary closure of wounds combined with a propensity to produce exuberant granulation tissue (‘proud flesh’). There are also other problem areas to consider, such as wounds over joints or in areas of high motion. In addition, a chronic nonhealing wound should be worked up as a clinical problem, with multiple differentials such as tumour formation, and underlying foreign body or open synovial structure.

Initial diagnostic approach

The initial examination should include cleansing of the wound to avoid pushing foreign material deeper into the wound during digital palpation. Wounds can be cleaned with water delivered through a hose, followed by use of sterile saline or betadine solution heavily diluted in tap water (to the colour of weak tea). Palpation may reveal deep clefts in the wound, foreign bodies, or communication with important underlying structures. Care should be taken not to overly probe wounds that may involve a joint or tendon sheath. Most chronic wounds will have what appears to be exuberant granulation tissue, and in the majority of cases it is this tissue that is in large part responsible for the lack of healing. However, exuberant granulation tissue is difficult to differentiate from tumours, particularly sarcoids. In addition, sarcoids may develop at the site of a wound. Thus, the tissue should be biopsied and sent to a veterinary pathologist for evaluation. On evaluation of this tissue, pathologists should also be alerted to the possibility of aberrant parasite migration, particularly Habronema spp. The latter has become uncommon with the advent of efficacious broad-spectrum anthelmintics such as the avermectins, but cutaneous habronemiasis is a consideration, particularly if the wound involves the external genitalia or eyelids. Consideration should also be given to culture of biopsied tissue. All wounds will culture positive for numerous organisms, so it is the magnitude of the infection that is important. […]