FRACTURES of the poll are relatively uncommon injuries. However, in recent years, we have seen two of these interesting cases at Mark Johnston Racing.

The poll is the bony prominence between a horse’s ears on top of its head. It acts as an insertion point for muscles to be anchored to the head.

It is, however, quite fragile hence, when it experiences blunt trauma, the bone can be fractured. Due to the elastic recoil of the muscle, once fractured, the fragment of bone is pulled away from its original position.

Both horses which fractured their polls were found to have banged their heads in their boxes. These injuries can be split into two categories, of which from our cases, we have had one of each.

Closed fractures of the poll occur where the bone is fractured but the skin does not have an open wound. The treatment required in these cases consists of anti-inflammatory drugs and a period of rest.

This allows the fragment to settle in its new position and scar tissue to form around the fracture site. During the period of rest, wearing of a bridle and any pressure on the poll are avoided to prevent causing pain until all inflammation has settled. The horse in the first X-ray, had a closed fracture which healed with a period of rest.

If there is a wound, the fractured poll is considered open. In these cases, bacteria is able to contaminate the wound and fractured bone. This sets up a grumbling infection and chronic purulent discharge persists as bacterial infection thrives on the broken bony fragments.

In these cases, the fragments must be surgically removed, the wound cleaned up and closure via suturing to speed healing if possible.

Our second case of a fractured poll was an open fracture. It was diagnosed using X-rays of the poll which showed a comminuted fracture (lots of fragments of the fractured bone). It was agreed that we would surgically remove the fragments under standing sedation and local anaesthesia.

The horse was heavily sedated. Local anaesthetic lignocaine was injected under the skin and deep into the muscle where the bone fragments were present, allowing us to carry out the surgery without the horse feeling what we were doing.

The area was cleaned using hibiscrub (chlorhexidine) to reduce the bacterial contamination of the already infected wound and the surrounding skin. X-rays were then taken using positioning aids to identify the position of the bone fragments within the muscle. These X-rays were taken from two angles to give us a multi-dimensional appreciation of their position.

Once the fragments were located, the wound was further opened with a surgical incision perpendicular to the original wound making a T-shape. We dissected through the soft muscular tissue until the fragments could be digitally palpated.

Forceps were applied to the fragments which were then worked loose from their muscular attachments using careful traction and blunt dissection.

As there were multiple fragments, X-rays were repeatedly taken during the surgery to observe the position of remaining fragments and to allow us to check we had fully removed all the fractured pieces of bone. This process of fragment removal is demonstrated on the sequential series of X-rays.

Once we were happy that all the fractured bone was removed the wound was lavaged (washed) using sterile saline to wash away any blood clots and loose tissue.

The muscular tissue was sutured using Vicryl, a suture material that breaks down and is absorbed by the body after a set period of time. This means that the sutures can be buried in the tissue and don’t need to be manually removed. The skin wound and surgical incision were then also sutured in an attempt to speed the healing process.

POST OP TREATMENT

The horse continued a prolonged period of the anti-inflammatory drug phenylbutazone and strong antibiotics, initially penicillin and gentamicin, followed by an oral course of enrofloxacin.

The wound healed well and the discharge present prior to surgery stopped quickly. As you can see from the pictures of the healing wound and surgical site a week after the operation, the wound is still healing in the middle where it could not be closed completely with sutures due to the tension on the skin from the soft tissue filling.

You can no longer see the additional surgical incision which has completely healed. This horse will now undergo a period of rest until the wound is completely healed and the fracture site is non-painful at which point he will resume ridden exercise and his training regime will return to normal.

A graduate of the University of London, Neil Mechie is a veterinary surgeon at Mark Johnston Racing. This article first appeared in the Kingsley Klarion.