Splints
Encyclopedia
Splints is an ailment of the horse
or pony
, characterized by a hard, bony swelling, usually on the inside of a front leg, lying between the splint and cannon bone or on the splint bone itself. It may be "hot," meaning that it occurred recently and is still painful; or "cold," meaning that the splint has completely recovered and there is no longer any swelling or pain associated with it. Bucked shins are sometimes called 'shin splints,'
which involve small stress fractures of the dorsal cannon bone, often seen in race training, and discussed elsewhere.
s of prehistoric horses
, run down either side of the cannon bone. They narrow as they go from the carpal or tarsal joint down, and form a "button" at the bottom or their length, a few inches above the fetlock. Splint bones are attached to the cannon by the interosseous ligament, providing some mobility in the young horse. As the horse ages, the interosseous ligament is typically replaced by bone. In some older horses, the cannon and splint bones may become completely fused.
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. The splints may occur in a front leg or hind, in one leg or both. Severe enough trauma can fracture the splint bone. If minimally displaced, and in the lower portion, some heal well. 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.
Bench-kneed conformation causes excess loading of the medial splint bone, which can lead to splints.
of the splint bone where the interosseous ligament attaches. The horse will then lay down new bone and the area will become inflamed. "Blind splints" are named because the bony reaction happens on the inside border between the splint bone and cannon bone, where it can not be seen, and is usually not palpable. Besides causing pain as any active splint reaction can, the swelling can impinge on the suspensory ligament. This condition is difficult to diagnose, but ultrasound
is generally diagnostic. MRI and CT also show these well.
(a grade of 1–2 out of 5). The injured area is hot, painful, and inflamed with a small bony swelling. However, splints do not always cause lameness, especially once "cold". More severe lameness is sometimes associated with a fractured splint bone, or soft tissue injury adjacent to the splints.
"Blind splints" usually produce mild lameness that is difficult to pinpoint because there is no obvious swelling, pain, or bony changes related to the exterior of the splint bone. At times, bone proliferation on the axial border of the splint bone can be seen radiographically, but ultrasound is much more sensitive for detecting blind splints.
The body will eventually absorb some of the bone it placed down in the splint, flattening out the splint over several months and possibly making it completely disappear. A splint involving the cannon alone is more likely to disappear than one involving the splint bone itself.
Several days of cold therapy, sweats, and NSAIDs can help a "hot" splint. NSAIDs can help reduce the inflammation and help the bone growth by doing so. However, none of these treatments are incredibly effective. The most important factor is time. Counter-irritants, which increase inflammation, only hinder the formation of bone and can actually prolong the healing process.
Surgery to remove the fractured end of the splint bone, particularly in the lower third, is typically successful. However, surgical removal of the bone growth in large splints, performed by chiseling it away, usually does not produce satisfying results. Often, bone growth is stimulated by the surgery, and the size of the splint is increased. Only about a third of the time is surgery at all successful.
Horse
The horse is one of two extant subspecies of Equus ferus, or the wild horse. It is a single-hooved mammal belonging to the taxonomic family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today...
or pony
Pony
A pony is a small horse . Depending on context, a pony may be a horse that is under an approximate or exact height at the withers, or a small horse with a specific conformation and temperament. There are many different breeds...
, characterized by a hard, bony swelling, usually on the inside of a front leg, lying between the splint and cannon bone or on the splint bone itself. It may be "hot," meaning that it occurred recently and is still painful; or "cold," meaning that the splint has completely recovered and there is no longer any swelling or pain associated with it. Bucked shins are sometimes called 'shin splints,'
which involve small stress fractures of the dorsal cannon bone, often seen in race training, and discussed elsewhere.
Anatomy
The splint bones, (metacarpal or metatarsal II and IV), which are remnants of two of the five toeToe
Toes are the digits of the foot of a tetrapod. Animal species such as cats that walk on their toes are described as being digitigrade. Humans, and other animals that walk on the soles of their feet, are described as being plantigrade; unguligrade animals are those that walk on hooves at the tips of...
s of prehistoric horses
Evolution of the horse
The evolution of the horse pertains to the phylogenetic ancestry of the modern horse from the small dog-sized, forest-dwelling Hyracotherium over geologic time scales...
, run down either side of the cannon bone. They narrow as they go from the carpal or tarsal joint down, and form a "button" at the bottom or their length, a few inches above the fetlock. Splint bones are attached to the cannon by the interosseous ligament, providing some mobility in the young horse. As the horse ages, the interosseous ligament is typically replaced by bone. In some older horses, the cannon and splint bones may become completely fused.
Causes
Direct trauma, such as from an interference injury or a kick from another horse, is a common causes of splints. The periosteumPeriosteum
Periosteum is a membrane that lines the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of all bones....
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. The splints may occur in a front leg or hind, in one leg or both. Severe enough trauma can fracture the splint bone. If minimally displaced, and in the lower portion, some heal well. 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.
Bench-kneed conformation causes excess loading of the medial splint bone, which can lead to splints.
Blind splints
Because the splint bone does have some mobility independent of the cannon bone, it can cause tension and strain on the periosteumPeriosteum
Periosteum is a membrane that lines the outer surface of all bones, except at the joints of long bones. Endosteum lines the inner surface of all bones....
of the splint bone where the interosseous ligament attaches. The horse will then lay down new bone and the area will become inflamed. "Blind splints" are named because the bony reaction happens on the inside border between the splint bone and cannon bone, where it can not be seen, and is usually not palpable. Besides causing pain as any active splint reaction can, the swelling can impinge on the suspensory ligament. This condition is difficult to diagnose, but ultrasound
Ultrasound
Ultrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
is generally diagnostic. MRI and CT also show these well.
Symptoms
Splints usually cause mild lamenessLameness (equine)
Lameness in horses and other equidae is a term used to refer to any number of conditions where the animal fails to travel in a regular and sound manner on all four feet...
(a grade of 1–2 out of 5). The injured area is hot, painful, and inflamed with a small bony swelling. However, splints do not always cause lameness, especially once "cold". More severe lameness is sometimes associated with a fractured splint bone, or soft tissue injury adjacent to the splints.
"Blind splints" usually produce mild lameness that is difficult to pinpoint because there is no obvious swelling, pain, or bony changes related to the exterior of the splint bone. At times, bone proliferation on the axial border of the splint bone can be seen radiographically, but ultrasound is much more sensitive for detecting blind splints.
The body will eventually absorb some of the bone it placed down in the splint, flattening out the splint over several months and possibly making it completely disappear. A splint involving the cannon alone is more likely to disappear than one involving the splint bone itself.
Treatment
The horse should have a reduced workload for 1–3 weeks. If a trainer does not decrease the workload sufficiently, and the splint bone continues to receive concussion, the injury is likely to continue or worsen. Light exercise on soft ground is best for a horse with splints, as work can help encourage the needed bone growth to heal the splint. Those trainers concerned with the cosmetic appearance of their horse usually prefer to hand-walk twice daily and keep the animal stalled until the splint is resolved, eliminating the chance that the splint will accidentally be knocked during work and the swelling increased.Several days of cold therapy, sweats, and NSAIDs can help a "hot" splint. NSAIDs can help reduce the inflammation and help the bone growth by doing so. However, none of these treatments are incredibly effective. The most important factor is time. Counter-irritants, which increase inflammation, only hinder the formation of bone and can actually prolong the healing process.
Surgery to remove the fractured end of the splint bone, particularly in the lower third, is typically successful. However, surgical removal of the bone growth in large splints, performed by chiseling it away, usually does not produce satisfying results. Often, bone growth is stimulated by the surgery, and the size of the splint is increased. Only about a third of the time is surgery at all successful.