Nature has a way of healing wounds in horses and for the most part, has a remarkable inherent ability to return the skin to its original state. However, horses, more so than any other species, tend to be particularly prone to a troublesome complication of wound healing referred to as ‘proud flesh.’ Whenever it appears, it prevents a wound from healing fully.
Proud flesh is the unchecked and unproductive growth of granulation tissue, a normal component of natural wound healing and which is necessary to fill in the wound bed. It is the newly formed reddish-pink granular or pebbly flesh that appears within a healing wound. It is very resistant to infection, fills the gap left by an open wound and provides the surface for skin cells to migrate and/or “crawl” across the wound.
While migrating, these skin cells produce chemical signals which encourage granulation tissue to contract. In doing so the wound edges are drawn towards each other, reducing the size of the wound. Once skin cells have covered the surface of the wound, the process of granulation tissue is switched off and remodelling and repair processes proceed at deeper levels.
Whenever the delicate balance between theses processes goes unchecked by the body, an abnormal accumulation of granulation tissue forms. The mounds of cauliflower-like pink tissue protruding beyond the surface of the wound are then referred to as proud flesh. Skin cells are no longer able to grow over the tissue bed and healing cannot continue.
Lower limbs prone
Although proud flesh can appear anywhere on the horse’s body, the lower limbs i.e. below the carpus (knee) and hock, are particularly prone to this affliction. Contamination, tension and/or movement across healing surfaces, or a history of ill-advised wound treatments, can disrupt fragile healing processes and tissues. This places a wound at an increased risk for the development of proud flesh.
A properly managed wound from the onset has fewer tendencies to develop proud flesh, even more so with wounds to the lower limbs.
If primary closure and/or suturing is not an option, the wound must heal through secondary intention with granulation tissue. Thorough cleansing of the wound as well as maintaining a clean environment for the healing tissue is ideal for productive healing. Hence bandaging of wounds on the lower limb is highly advised. In addition to maintaining a healthy environment for healing, well-placed bandages can reduce motion across the wound surface and create pressures which help prevent granulation tissue from becoming exuberant.
Fragile and delicate healing tissues can become very reactive when inappropriate dressings are applied to the wound surface. For all stages of healing, use only products labelled for use on horses. Simple dressings such as Derma Gel and moistened saline pads are recommended. Meat tenderizers, used oil, lime bluestone and other home remedies irritate and significantly affect the behaviour of the granulation tissue, often leading to its overexuberance.
Once initiated proud flesh can become quite a nuisance to resolve. If the flesh begins to grow beyond the level of the wound edges a number of options are available to the horse owner.
Mild overgrowth of tissue i.e. barely protruding above the surface of the wound, will most likely be controlled with the application of a corticosteroid cream and/or bandaging.
When the growth of proud flesh becomes moderate to severe, surgical removal is generally the preferred course of treatment. Excessive non-viable granulation tissue is excised to be level with the skin’s edges. This then allows the skin cells to crawl over the wound once again.
While there are no nerve endings in granulation tissue, it does have an extensive blood supply. Bleeding can be quite pronounced once the excessive tissue is debrided, often requiring a pressure bandage to control the bleeding. The extent of the proud flesh may or may not necessitate sedation or anesthesia of the horse.
Following surgical removal of proud flesh, a corticosteroid cream and/or ointment may be prescribed by the attending veterinarian. Topical corticosteroids have been shown to inhibit the formation of granulation tissue without inhibiting epithelialization or formation of superficial skin cells. Under certain circumstances a cast may be necessary to prevent the granulation tissue from regrowing and enable the skin edges to advance and cover the wound.
A number of caustic products are promoted to horse owners to “eat away” proud flesh. The problem with caustic substances is that they non-selectively destroy both healthy and non-healthy tissues, further damaging the wound. The surgical method of addressing proud flesh tends to result in the best overall healing and cosmetic results, as it removes the unwanted granulated tissues while leaving the healthy tissue unharmed.