How do wounds heal?
WOUND HEALING HAPPENS in several different overlapping stages. It starts with an acute inflammatory phase which lasts about four to five days. This is where the body sends inflammatory cells to the site of the wound to try clear up any bacteria or dirt contamination. This is why in the first few days the dressing often gets soaked through very quickly with what we call exudate, which is fluid and dead cells, all aiming to clean the wound and remove contamination. The dressing needs to be changed more often during this phase. Next is the proliferative phase, which is when granulation forms. This is the pink sponge-like tissue that rapidly fills in the wound – too much of this is what we call
Epithelialisation and contraction also now occur. Contraction of the wound makes it rapidly smaller – this more easily happens with wounds on the body as there is more skin available compared to the legs. Epithelialisation is what we call the very thin layer of skin growing in from the edges of the wound. This takes time to grow across the wound and explains why wounds on the legs, which can’t do much contracting, take longer to heal.
Epithelialisation can be a difficult process and can be hindered by several factors. If the wound get too dry then it will slow down. Proud flesh which bulges out over the surrounding skin will stop this layer of skin growing over the wound. Even a dressing which sticks to the wound can result in this layer being pulled off,
– this just means something present in the wound that shouldn’t be there. Soil or small splinters of wood are good examples; a clean wound is vital. Presence of necrotic(dead) tissue – this is skin, muscle or tendon that has lost its blood supply and dies off. This then acts as a foreign body. Vets will often cut off flaps that have lost the blood supply, as although it makes the wound bigger to start with, removing dead tissue actually allows healing to progress. Sometimes the flap will be left in place initially to protect the rest of the wound. A skin flap may also trap dirt at the junction with normal skin which may be another reason for it to be removed.
1. Safety for everyone is the first priority.
2. Get help, call the vet if needed.
3. Look at the whole horse not just the wound – there may be something else going on.
4. Stop any bleeding (if safe to do so).
5. Clean wounds thoroughly; saline is a good option, no strong antiseptics.
6. If veterinary attention not needed then bandage in three layers – dressing, absorptive layer, outer layer.
7. Ensure tetanus vaccination up-to-date.