Granulation Tissue Management in the Horse (AAEP 2011)

There is a saying that "anything worth doing is worth overdoing." When it comes to healing lower leg wounds, some horses take this advice to heart and essentially "overheal" their injuries, resulting in the production of unsightly granulation (scar) tissue, commonly known as proud flesh. At 2011 American Association of Equine Practitioners convention, held Nov. 18-22 in San Antonio, Texas, Richard Hackett, DVM, MS, Dipl. ACVS, from the Department of Clinical Sciences at Cornell University's College of Veterinary Medicine, discussed how to prevent the development of exuberant granulation tissue.

"Horses have little extra skin in the lower limbs, so injuries to this area often need to heal by a process called second intention healing," explained Hackett. "This means that granulation tissue needs to fill in the defect and cover tendons, ligaments, bone, and other important structures before new skin cells can migrate over top of the scar tissue to repair the wound. Granulation therefore produces much-needed healing tissue, but in some horses the process continues unabated and too much granulation tissue is produced."

In these horses, excess scar tissue is produced, and the skin cells aren't able to migrate over top of the scar tissue to ultimately heal the wound. The result is a large, unsightly ball of tissue protruding from the limb.

Hackett relayed several important facts about granulation tissue production, along with techniques for preventing and managing it:

  • Exuberant granulation tissue (EGT) occurs more frequently in draft and other large breeds;
  • Wounds on the lower limb--especially in high-motion areas (e.g., heel bulbs, the front of the fetlock)--that cannot be sutured, but are left to heal by themselves, are more likely to develop EGT;
  • Wrapping wounds with a commercially available silicone gel dressing can help reduce the likelihood that the granulation tissue will become exuberant;
  • Any EGT protruding above the adjacent skin must be removed;
  • Open wounds can become neoplastic (cancerous), and biopsies might be indicated; and
  • Tissue grafting can be performed after the wound has finished contracting (closing) to help skin cells migrate over the scar tissue bed to achieve complete wound healing.

When faced with wounds that have the potential to develop EGT, Hackett recommends horse owners minimize exercise for the animal, keep the wound clean and covered with a bandage and silicone dressing, and contact a veterinarian if tissue begins to protrude above skin-level.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.

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