How do wounds heal?

NZ Horse & Pony - - Our Month -

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.

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