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Equine Health Resource

Navicular Bursa Penetrated by Foreign Body

Synonyms: Street Nail Injury

The navicular bursa is a tiny, fluid-lined sac within the heel of the hoof. It rests between the deep digital flexor tendon and the navicular bone as the tendon passes over it. It helps smooth the deep flexor tendon’s action and reduces friction as this tendon passes passes over the bone.

Nails and screws penetrating near the frog or heel can penetrate the deep digital flexor tendon and bursa, damaging and introducing bacteria into these structures. Resulting lameness is usually very severe. In most cases, horses cannot bear weight on the limb. Within hours, swelling may migrate up the limb. These are disastrous injuries. Early diagnosis and aggressive treatment is the only hope for return to soundness.

After the nail or other foreign body has been removed, diagnosis may require a variety of techniques including radiography, ultrasound and sampling of the fluid from the navicular bursa to establish that the bursa is involved.

In the past, this injury was treated with what is known as a “street nail procedure.” In this operation, a large central window of the frog and deep digital flexor tendon is surgically removed, to allow proper drainage of the bursa. Today, this is still a possible treatment, but should be considered after other less invasive treatments are considered. In most cases, horses that undergo a street nail procedure will have some degree of chronic lameness.

Any nail puncture can cause non-weight bearing lameness. It is critical for your vet to differentiate a simple abscess from infection of this area because rapid and correct treatment is important.

Prognosis & Relevant Factors

The prognosis is poor to grave if not promptly diagnosed and treated. Even with prompt diagnosis and treatment, the prognosis is guarded. There is always a possibility of long-term lameness.

Arthroscopic approaches to management of this problem have improved the prognosis by allowing more meticulous cleanup of the area without removal of the flexor tendon and frog tissues.

QUESTIONS TO ASK MY VET

  • With the different treatment options, what are the odds my horse will return to prior level of performance?
  • What will aftercare entail?
  • What are the predicted costs associated with treatment?
  • PREVENTION

    Keep stables and pastures clean of nails, screws and other metallic foreign bodies. If your horse steps on a nail or screw, consider it a life threatening emergency. Involve your vet from the beginning.

    Leave the nail in the hoof if your vet recommends this, and they can get to you quickly. This way your vet can radiograph the hoof with the nail in place and quickly determine whether or not the nail has penetrated important structures.

    Author: Doug Thal DVM Dipl. ABVP

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