Acquired flexural deformity of the metacarpophalangeal joint in five horses associated with tendonous damage in the palmar metacarpus.

The research investigates five cases of joint deformity in older horses linked to tendon damage in the lower leg. The study indicates that the prognosis for this condition in older horses and ponies is poor.

Study Overview

• The researchers studied five cases of metacarpophalangeal joint (MCPJ) deformity in horses and ponies, with an average age of nearly 15 years. These involve the joints connecting the hand (or forefoot in quadrupeds like horses) with the fingers (or toes in animals).
• The deformities observed were acquired, implying that they developed over time possibly due to factors like injury, aging, or disease rather than being present at birth.
• The deformity was characterized by a noticeable change in the joint’s shape or alignment, causing significant lameness in all cases.

Role of Tendon Damage

• In four out of five cases, the deformities appeared following inflammation or injury to two key tendons in the lower leg – the accessory ligament of the deep digital flexor tendon (ALDDFT) and the superficial digital flexor tendon (SDFT).
• The remaining case involved inflammation or injury to the SDFT alone. This indicates that damage to the SDFT, either alone or in combination with damage to the ALDDFT, seems to be a common factor in these deformities.
• Ultrasonographic examinations revealed extensive adhesion (scar tissue) between the ALDDFT and SDFT, and reduced size of the deep digital flexor tendon in each case, further reinforcing the connection between tendon damage and the deformity.

Prognosis and Treatments

• Several treatments were attempted but none helped remedy the condition, indicating that these types of joint deformities in horses may be difficult to treat.
• The prognosis, or outlook, based on this limited sample of cases, is poor for older horses and ponies with such an acquired MCPJ deformity following tendon damage in the palmar metacarpus (the back part of the animal’s lower leg).
• This suggests that prevention or early intervention may be more effective in dealing with this issue, although this research does not delve into those aspects.