Canker and Thrush in Horses’ Hooves

Claire Dunling

Thrush in horses is a condition affecting the frog of the foot, in most cases, the horse will appear perfectly sound and untroubled. However, if left untreated it can spread to other parts of the foot like the hoof wall and heel bulb. This can lead to some pain around the affected areas, limb swelling and at worse, result in lameness.

Canker and Thrush in Horses

Thrush in horses usually develops due to poor hygiene, failure to clean out a horse’s feet regularly or if the horse is kept in damp and dirty conditions. As their hoof is continually damp and dirty it allows keratonolytic bacteria to attack the frog causing it to rot. Signs of thrush usually include a black, foul-smelling, moist discharge in the affected frog. Affected areas will be painful when palpated with the hind feet more commonly affected. There may also be some concurrent swelling of the distal part of the affected limb.

Can thrush in horses’ hooves be prevented?

This condition is easily prevented with good horse care and good hygiene – daily cleaning of the stable and regular healthy hoof inspections. Regular attention from a farrier ensures a healthy hoof and avoid the development of long heels keeping the frog healthy. It is also important that your horse has regular tetanus vaccinations, as thrush can allow tetanus to infect your horse. Advice on vaccination and good horse care can be sought from your vet.

Canker in horses

Horse canker is a more serious form of thrush in horses’ hooves and alters the normal growth of the horse hoof wall. Thankfully nowadays it is rarely seen and is most often seen in horses kept in wet tropical climates, or in large draught type horses. Canker in horses affects the hind legs primarily.

What causes canker in horses?

As for horse thrush, horse canker is predisposed to long heel conformation, which results in deep sulci (clefts) adjacent to the frog. Damp dirty conditions develop within the sulci allowing bacteria and fungi to invade. This infection then extends from the frog to the sole and wall and in advanced cases to the sensitive underlying tissues of the horse hoof.

What are the signs of canker in horses?

Horse canker generally originates in the frog and can be mistaken for horse thrush in the early stages. Whilst thrush is limited to the sulci or the base of the frog, canker in horses invades the horn of the frog anywhere throughout its structure. Horse canker also causes the horse hoof tissues to grow excessively whereas horse thrush destroys them. Lameness is not usually associated with canker in horses early on but horses may stamp their feet due to the irritation. As the disease progresses, lameness may develop depending on the severity of the condition. The lower limb may also begin to swell as deeper tissues become involved in the condition and become inflamed.

Can I prevent horse canker?

This condition can be prevented by good hygiene – daily cleaning of the stable and regular horse care and inspection. Regular attention from a farrier to maintain a healthy hoof and ensures the development of long heels is avoided, also to keep the frog healthy. It is also important that your horse has regular tetanus vaccinations as horse thrush can allow tetanus to infect your horse. Detailed advice on healthy hoof-care and vaccination can be sought from your vet.

The article is an opinion and should only be used as a guide. You should discuss any change to your horse’s care or lifestyle thoroughly with you vet before starting any program or treatment.

If in doubt contact your veterinary practice

And always keep your vet's phone number handy - just in case!