Page 310 - The Veterinary Care of the Horse

However, the tendon only has the capacity to cope for so long and there is a limit to the

amount of damage that can be sustained before the horse goes lame.
VetBooks.ir injury. The lesion tends to occur in the centre of the tendon structure and is known as a ‘core’
The narrowest part of the SDFT is at mid-cannon level and this is the commonest site of

lesion.

ACUTE INFLAMMATORY PHASE

This typically lasts from a few days from the time of injury up to 2 weeks later, depending on
the severity of the strain. There is considerable swelling, inflammation and haemorrhage into

the tendon resulting in oedema and an increased blood supply including white blood cells
(neutrophils, monocytes and macrophages) which clear up the damaged tissue.

SUBACUTE REPAIR PHASE

During the healing process which starts a few days after the injury, cells called fibroblasts
migrate into the areas and produce new collagen. This repair (type III) collagen is randomly
arranged and it forms scar tissue which is not as strong or elastic as the original (type 1)

collagen. The tendon becomes thickened and bowed and is prone to re-injury at this stage. As
the inflammation subsides, so the lameness resolves.

REMODELLING PHASE

This phase of healing begins 2–3 months after the injury occurred and can last for up to 15
months. The type III collagen is gradually replaced by type I. Cross-links develop between

the collagen fibrils and increase the strength of the scar tissue. Controlled exercise
encourages the longitudinal alignment of the fibres. The fully healed area is thicker and
stronger but less elastic than the original tendon. This puts the adjacent areas under increased

strain and they are thus more prone to break down.

Treatment

The aims of treatment are to:
• relieve the pain

• reduce the swelling and inflammation

• provide support

• encourage successful healing with longitudinal alignment of the collagen fibrils.

A severe tendon injury is a medical emergency and treatment should be instigated straight