Login to Download
PDF version

Veterinary Wounds

  The Westgate et al review summarizes current research related to equine wound healing and wound care. The review also outlines the role of microbes and associated bacterial biofilms in the delayed healing of chronic equine wounds. Biofilms are defined as a group of microorganisms that are encased within a three dimensional matrix of extracellular polymeric substances and irreversibly attached to a biological or nonbiological surface.¹ Bacteria within biofilms are resistant to traditional therapy

The biofilm concept explains many features of persistent infections and is consistent with clinical experience in treating chronic wounds. The understanding of the biofilm phenotype is important in the understanding of bacteria in vitro but it has been, and still is, difficult to translate biofilm science to the clinical setting.
  It has been known for some time that bacteria communicate with each other using quorum sensing, which involves diffusible signal molecules moving between cells. Relatively recently it has become known that quorum sensing also regulates biofilm formation. This is leading to the development of quorum sensing inhibitors such as the brominated furanones that block quorum sensing by acyl homoserine lactones, signal molecules Gram-negative bacteria use. Gram-positive bacteria use cyclic peptides for this purpose.^2,3
  In uncomplicated acute wounds such as a surgical incisional wound, the healing process is normally expected to be complete within 2 weeks with ongoing restoration of tissue tensile strength continuing for a few weeks thereafter. The chronic wound does not progress sequentially through the “normal” stages of wound healing with inhibited stages being the principle pathological processes.⁴ A more meaningful definition of wound infection is the point when the host’s immune response is stimulated. The organisms within biofilms are renowned for their resistance toward the host immune response and antibacterial agents when compared to their free-living planktonic counterparts. An impaired host immune response is not able to decrease the bacterial level within a wound sufficiently to prevent clinically significant infections from developing.
  Chronic wounds in horses have a similar pathophysiology to human chronic wounds.⁵ Management practices utilized for human chronic wounds are therefore being employed successfully in the management of equine traumatic and chronic wounds. Assessment of wound-healing kinetics in the presence of biofilm has confirmed causality between biofilm and impaired wound healing. Consequently, biofilms are of significant importance to both clinical and veterinary science. However, although bacterial infections are widely reported in animals, their association with biofilms is rarely discussed. This review gives an overview of the impact of biofilms on the healing of equine wounds, particularly those occurring at problematic anatomical sites such as the lower distal limbs where there is a relatively poor blood supply with consequent reduced tissue oxygenation compared to the thoracic region.
  It is known that an increased microbial bioburden in the lower limb, compared to thoracic wounds, significantly delays healing. The precise mechanisms for this remain unclear and is an area where major research leading to increased understanding of this important factor will significantly impact the costs of managing these wounds and improve the morbidity, and in some cases mortality, of these equine patients.

From the Welsh School of Pharmacy, University of Wales
Cardiff, Wales, United Kingdom


Address correspondence to:
Dr. Sarah Cockbill
Welsh School of Pharmacy
Cardiff University, Redwood Building
King Edward VII Avenue
Cardiff, CF10 3XF
United Kingdom
Phone: 44 029 2087 6241
E-mail: cockbill@cardiff.ac.uk