The Magazine December 2017

How a wound heals

Posted 13th October 2017

 

Horses tend to be accident-prone, which means that dealing with wounds is part and parcel of being a horse owner. Vet Sally Hodgson, from Hook Norton Veterinary Group, explains how wounds repair and how you can help the process

Horses have an incredible ability to injure themselves on virtually anything and, quite often, the cause of a wound remains a mystery. But whatever the type, severity or cause, understanding more about how wounds heal will help you ensure your horse’s injury has the best chance of repairing as quickly and neatly as possible.

The healing process

For a wound to heal, three processes have to take place and they overlap in time and space – this means that different areas of a wound may be undergoing different healing processes at the same point in time.

  1. The inflammatory and debridement phase. Any dead or dying tissue has to be removed, and bacterial contamination or infection brought under control. Inflammation is the body’s initial response to a wound and it brings immune system cells to the area to start cleaning up. This produces a thick discharge. Debridement means the removal of dead or damaged tissues. This phase may last up to five days.
  2. The repair phase. Any tissue lost due to the wound is replaced in the repair phase. This usually begins within 12 hours of trauma, but it can’t be completed until the debridement phase has ended. The time taken to repair the damage depends on several factors, including how much tissue has to be replaced, how good the blood supply to the area is, and how long the inflammatory and debridement phase lasts. Lost tissue is replaced by a layer of granulation tissue that brings new blood vessels and specialised cells called fibroblasts, which make tiny strands of a type of collagen. The granulation tissue is quite weak until 5–15 days post-injury, when it becomes much stronger.
  3. The maturation phase. A new top layer of skin must grow across the granulation tissue – this is called epithelialisation. New skin cells must move inwards from the blood vessels at the edges of the wound. Epithelialisation is a very slow process – at best the new cells can migrate 1.5mm in 10 days. As the new area of skin forms, the blood supply behind the healing edge decreases and the cells shrink and become more densely packed together, forming a scar. This process is called contraction. Contraction contributes to the reduction in size of a healing wound by reducing the area needing to be covered by epithelialisation. Wounds can’t heal without producing some scarring, however massaging the scar tissue using aqueous cream may help to reduce the final size of the scar. Wound contraction continues for months after the wound has closed over.

Types of wound

There are various different types of wound your horse can sustain. The most common include lacerations, puncture wounds and incised wounds. Other types include grazes, bruises, haematomas, contusions, complicated wounds and burns. 

To find out more about different types of wounds, what can cause them and how you can help the healing process, get your copy of December Horse&Rider, out now.

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