SPLINTS IN HORSES

Splints are caused by injury to the interosseous ligament or to the periosteum of the splint bones or adjacent bones .

Splints can originate from tearing of the interosseous ligament, external trauma to the bone, or secondary to healing of a fracture.

Splints commonly occur in 2- to 3-year-old horses, occasionally in horses 4 years of age and older, and are usually associated with training and subsequent injury,

Splints usually occur in the medial (inside) forelimb splint, although they can occur in the lateral (outside) splint of the front or rear legs.

Four Types of Splints

1. True splint
   This is a fibrous and bony enlargement at the interosseous space secondary to inflammation or tearing of the interosseous ligament.
2. Blind splint
   The inflammation this causes results in a fibrous and bony enlargement between the splint bones and the suspensory ligament (i.e., little to no external swelling).
3. Periostitis
   This inflammation and bony reaction is secondary to trauma to the periosteum .
4. Knee splint
   This type of splint involves swelling located very proximally (toward the upper part of the splint bone, closer to the knee) and involving the lower joint in the knee, resulting in osteoarthritis.

Causes

Direct trauma, such as from an interference injury or a kick from another horse, is a common causes of splints. The periosteum is damaged by the trauma, and the horse's body lays down new bone in the injured area. Splints caused by trauma are more commonly seen lower down the leg than ones caused by strain. Severe enough trauma can fracture the splint bone. Others may need surgical removal of a portion of the damaged splint bone.

Concussion is another cause of splints. Concussive forces run from the carpus or tarsus into the splint bones. Working a horse on hard surfaces increases the concussion received by the interosseous ligament, which causes tearing. Splints caused by concussion are usually found on both front legs, most commonly on the inside of the leg a few inches below the knee.

Overworking young or unfit horses at speed or in tight circles may cause splints. The uneven loading of the limb in tight circles places excessive force on the medial splint, which can cause it to move excessively relative to the cannon bone, causing tears in the interosseous ligament and periosteal reaction.

Symptoms

The injured area is hot, painful, and inflamed with a small bony swelling. However, splints do not always cause lameness, especially once "cold

Treatments

The horse should have a reduced workload for 1–4 weeks.

Pressure bandaging to reduce swelling; oral non-steroidal anti-inflammatory drugs to reduce inflammation; and topical anti-inflammatory drugs such as DMSO (dimethyl sulfoxide)

Anti-inflammatory agents are primarily indicated for the acute phase, whereas intralesional injections of steroids may be used in the subacute case to further decrease inflammation and reduce swelling."

Some chronic or severe cases might require surgery to remove the bony swelling or to remove a portion of the splint bone

Prognosis

Prognosis is excellent in uncomplicated cases. The horse will be able to return to full work once the inflammation and pain ceases.