How to Use Foot Casts to Manage Horses with Laminitis and Distal Phalanx Displacement Secondary to Systemic Disease

Foot casts have been recommended for horses with distal phalanx displacement.¹ Stabilization of the hoof capsule and more uniform weight distribution by the cast may prevent additional damage. However, the prognosis for rehabilitating a horse with distal phalanx displacement remains poor after a palpable ledge or separation is evident around the entire coronary band. Author’s address: Rood and Riddle Equine Hospital, PO Box 12070, Lexington, KY 40580-2070; e-mail: [email protected].

1. Introduction

Despite significant research and recent findings over the past decade, a complete understanding of laminitis and its complex pathophysiologic processes remains unknown. Although preventative measurements and strategies to manage this devastating disease remain largely empirical and anecdotal, with little information from evidence-based medicine, recent technological advances offer some promise for the effective treatment and/or rehabilitation of the laminitic horse.

Laminitis may result in failure of the attachment between the distal phalanx and the inner hoof wall, causing unrelenting pain and characteristic lameness. Distal displacement of the distal phalanx is a well-recognized and devastating complication that may develop. The mechanical collapse of the distal phalanx can occur at any point around the lamellar attachment of the bone to the hoof wall. Distal phalanx displacement occurs in three different patterns: dorsal rotation, symmetrical distal displacement, and uniaxial distal displacement.²  During dorsal rotation, the distal phalanx separates from the dorsal hoof capsule and rotates about the distal interphalangeal joint (rotation). Symmetrical distal displacement or sinking occurs when the lamellae mechanically collapse evenly around the entire attachment to the hoof wall and the third phalanx displaces distally into the hoof capsule. Uniaxial distal displacement occurs when the lamellae mechanically collapse on only the medial or lateral aspect of the hoof capsule. Although each type of displacement may occur independently, a combination of the three types of displacement is often exhibited in many horses.²  The region of the foot under the greatest load is usually the first area to become compromised. Most horses at stance phase load the medial toe region on the front feet and lateral toe on the hind feet.

Therefore, horses suffering from laminitis on the forelimb usually rotate and sink medially, whereas in the hindlimb, they usually sink laterally and rotate.³ 
 

In general, the specific objectives to limit displacement of the distal phalanx should include (1) reducing effective body weight, (2) recruiting all or parts of the sole and frog to bear and share weight, (3) redistributing weight-bearing from the most stressed portion of the wall to the least stressed portion of the wall, and (4) decreasing the moments around the distal interphalangeal joint.^4,5

The objective of this paper is to describe the use of foot casts for horses with laminitis and distal phalanx displacement secondary to systemic disease. Foot casts extending from the hoof to just distal to the metacarpo/tarsophalangeal joint are believed to stabilize the entire foot, decreasing independent movement of the hoof capsule and bony column, with the goal of reducing shearing and twisting of the lamellar interface. Stabilization of the hoof capsule and more uniform weight distribution by the cast may prevent additional damage by reducing the likelihood that small areas of lamellar damage may propagate to adjacent areas as the hoof capsule independently moves, creating more diffuse areas of separation. The foot cast should include axial support and ease of breakover in all directions.¹

2. Materials and Methods

Medical records from Rood and Riddle Equine Hospital from 2005 to 2011 were reviewed. Horses were selected for inclusion if they had a diagnosis of laminitis secondary to systemic illness and were treated with foot casts. Information recorded included age, sex, breed, use, primary systemic disease, feet affected with laminitis, treatment instituted before foot cast application, grade of lameness immediately before casting was performed, grade of lameness immediately after casting, grade of lameness when casts were removed, time from admission until foot cast application, time from on- set of clinical signs until deep digital flexor tenotomy was performed, hospitalization status, and outcome.

All of the horses were closely monitored daily for comfort level or any signs of lameness. 
 

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