Wound Healing in the Horse / Fibrosis and Scarring

Horses respond to danger with a fight-or-flight instinct, predisposing them to massive skin wounds. Whereas even extensive wounds of the head and trunk usually heal uneventfully, horses display a debilitating impediment to repair of wounds of the extremities. Specifically, they suffer from chronic non-healing wounds similar to venous leg ulcers of man or, conversely, from the development of exuberant granulation tissue (EGT) which, in some ways, resembles the human keloid.


Since most horses are destined to an athletic career, defective wound repair and excessive scarring are an important economic burden to the equine industry. 


In the Theoret lab, we are studying the basic mechanisms underlying aberrant repair with the ultimate aim of identifying specific therapeutic targets to control the development of EGT. Studies to date have incriminated persistent local upregulation of profibrotic cytokines, an imbalance between collagen synthesis and lysis and deficient apoptosis of the cellular components of granulation tissue. Moreover, ongoing research strongly suggests that acute hypoxia in limb wounds promotes a feeble yet prolonged inflammatory response, thought to contribute to the development of equine dermal fibroproliferative disorders such as EGT. Indeed, in vitro studies show that the equine dermal fibroblast responds to the hypoxic situation present in vivo, by upregulating synthesis and downregulating turnover of extracellular matrix molecules, thus contributing to the fibrosis observed during wound healing.


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