Deep foot penetration

Wounds, lacerations and puncture wounds can affect the sole, the wall and the coronary band of the foot. Depending on the depth only the cornified tissue can be involved but deeper wounds can also involve the laminae/corium and/or underlying pedal bone, soft tissue structures (DDFT, impar ligament, digital frog cushion) or synovial cavities (DIP joint, navicular bursa, digital flexor tendon sheath). Deep wounds have an increased risk for serious complications and the need for early correct diagnosis of the affected structures and the institution of a correct aggressive medical and surgical intervention can not be overemphasized.

Common mistakes are assuming the wound is superficial, with inappropriate trimming and removal of affected tissue leading to entrapment of dirt and bacteria. Delaying an appropriate medical and meticulous surgical treatment, may be the difference between a full return to soundness and humane destruction.

This lecture will focus on

• the diagnosis of involved tissue.
• when and how treatment can be safely performed at the stable/farm.
• how to monitor succesful healing.
• which cases can not be treated at the stable and need to be referred to an orthopaedic specialist working in a hospital environment.
• what can be done in a referral centre.

Nail punctures:
Nail punctures or deep penetrations of the sole or frog are always an emergency. In general as soon as the corium has been penetrated lameness is very quickly apparent. Unfortunately the depth of the penetration is difficult to ascertain and the degree of pain/ lameness does not help to define the structures that are involved.

The first question that needs to be answered is whether the puncture wound penetrated a synovial cavity (DIP joint, navicular bursa, digital flexor tendon sheath) and/or a tendinous structure (DDFT, impar ligament). This requires a methodical examination of the foot.

• If no clean surface can be provided the horse should be transported to another examination area or referred to a hospital.
• If the nail/foreign body is still in the frog and weight bearing does not push the object deeper, the foreign body should not be removed until radiographs are taken.
• If the foreign body is not present anymore, the penetration place should be located (visual inspection, hoof tester, superficial paring of the sole and localisation of entry place).
• Make sure you have enough qualified people to help you.
• Sedate the horse and use a perineural block of the digital nerves.
• Clean sole and frog, remove dirty horn and clean sole and frog with antiseptic soap.  
• Determine depth and direction of penetrating wound with a sterile probe.
• Take LM radiographs with a probe in place.
• Ultrasonography and MRI can greatly assist with an accurate diagnosis and complete visualisation of the nail tract and the affected structures.
• If impar ligament, DDFT, navicular bursa, DIP joint or digital flexor tendon sheath is involved referral to a hospital is in the best interest of the horse.
• If P3 is injured or only corium/digital frog cushion is injured further treatment can be carried out at home.

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