What happens when a horse's foot abscess becomes serious

Steph Cook BVM&S MRCVS, from Scott Mitchell Associates, a member of Equine XLVets, explains what happened when she met a horse whose foot abscess had taken a turn for the worse...  

I met Daisy, an eight-year-old warmblood, when she was suffering from severe lameness on her left hind. On closer inspection, Daisy was found to have an abscess in her foot.

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Abscesses happen when a crack forms in the sole of the hoof and allows moisture, dirt and bacteria to get in.

Infection sets in and you get a build up of black pus. The hole then closes over and the pus is stuck in the hoof cavity with nowhere to go, causing a painful foot.

In simple cases, you can find the abscess tract while examining the foot and open it up with a paring knife. This lets the pus drain out through the hole, relieving pressure.

We then apply a poultice to draw out any remaining pus and the lameness soon resolves.

Difficulties with Daisy

Sadly, Daisy’s case was more serious. Her abscess was located just below the point of her frog and towards the outside of her foot, but it went rather deep and she had an underrun sole.

This is where there's a separation of the sole between the abscess, and it forms two layers of sole.  

I decided to par her foot out, but Daisy also needed X-rays of her foot to check how far into her foot the abscess was going.

When Daisy came back in for X-rays, I pared out her foot again and there was yet more pus in the hole.

The X-rays showed a slightly mottled edge to the pedal bone, lying under the area where the abscess was tracking. This showed us that the infection had spread to involve the bone. She was going to need this infected area of bone removed.

We prepared Daisy by soaking and scrubbing her foot in iodine. She was sedated and an intravenous catheter was placed so that she could have a constant flow of low-dose sedation to keep her calm, still and sleepy throughout the procedure.

I injected local anaesthetic into a nerve above her foot to prevent her feeling anything during the procedure. We put a catheter into a small vein above her foot and placed a tourniquet above this to stop the blood from her foot going around her body.

We then injected antibiotic straight into this vein. This enables a high concentration of the antibiotic to get to where it's needed and stay there for some time, rather than going around her whole body in her blood stream.  

We donned gowns and gloves and scrubbed the site of the abscess to ensure it was sterile. After this, we removed the infected area of bone from the abscess site and applied a sterile poultice.

After the operation

In the days following Daisy's operation, her poultice was changed daily until the bone had started to granulate (this is where it gets a hardened edge).

At this stage, she could go back to normal poultice dressings without them needing to be sterile, as the bone was healing over.

She was sent home and her owner continued with the poulticing as normal and kept her in her stable out of the mud.

We then went back to see her a few days later and met with the farrier who placed a shoe on with a sole pad underneath.

This pad would protect the hole from getting anything in it and give it cushioning until it completely grows and fills in again.

Now Daisy's allowed back out in the field and very pleased about this she was too!

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