From nails, screws and blackthorns to a piece of deer antler and an entire stud from a pair of cricket shoes, I have encountered a remarkable range of foreign bodies lodged in horses’ hooves.
Nails from waste wood — especially if a bonfire has been held in a paddock — are the principal offenders, although nails resulting from shoe removal can be trodden on if the floor is not swept carefully afterwards.
A pointed object that is sufficiently sharp can be driven into the sole or frog if stepped on. From there, it may be dislodged or remain embedded in the hoof. Commonly, the object is deflected into the groove in the centre or on each side of the frog, which is where most penetrations occur.
The outcome very much depends on the position in which the nail lodges and both the angle and depth of penetration. Deep penetrations through the middle third of the frog, considered the “danger zone”, can have serious consequences, as the foreign object is more likely to enter the synovial structures in the foot — namely the coffin joint or the navicular bursa.
In addition, the deep digital flexor tendon (DDFT), which runs down the back of the pastern and inserts into the underside of the pedal bone at the level of the sole, may be damaged. Penetration of these structures is associated with rapid infection, a poor long-term outcome and often incurable lameness in the horse.
Infection risk
While a puncture wound to the sole may look insignificant, the potential for infection should not be underestimated.
A study in 2013 looked at 95 cases of deep penetration of the navicular bursa or coffin, treated in four UK veterinary hospitals. Sadly, these wounds can be fatal and of those horses treated in the study, only 56% survived to be discharged, with only 36% returning to their previous level of athletic activity. The outcome was worse when there was a delay in referral, or where penetration occurred through the central frog groove.
Should the offending object penetrate the danger zone, then speedy referral to a hospital enables diagnostic investigation such as MRI or radiographs (X-rays) to take place quickly. Surgical intervention can then be performed before infection becomes established. Arthroscopy (keyhole surgery) has been shown to give a better outcome than more radical open surgery and is best performed in specialist centres.
If a “safer” area of the foot is penetrated, the horse is more likely to develop a local abscess that can be dealt with without hospitalisation. Your vet can advise whether your horse should be hospitalised for investigation and intensive treatment.
What to do…
If you find a penetrating object such as a nail in the sole, this is what to do:
- Carefully clean the horse’s foot, so you can assess the location and angle of penetration.
- Resist the temptation to remove the object if it is in the danger zone. Pending the vet’s arrival, bandage small blocks of wood on the underside of the hoof, on either side of the entry site, to prevent the nail from being driven deeper.
- If the nail is removed, note carefully the precise site it entered the foot, along with the direction, angle and depth of penetration. Retain the nail for the vet to inspect.
- While waiting for the vet to arrive, verify whether the horse is vaccinated against tetanus and has had a booster injection within the past two years.
Ref Horse & Hound; 18 April 2019
