What Are Splints In Horses – Causes & Treatment
As equestrian’s, our minds have been deeply imbedded to always look at our horses’ legs, to run our hands over them, to look for heat, inflammation, to feel for those unusual lumps and bumps. As one of the most frequent injuries seen by equine clinicians, those lumps and bumps found along the horse’s cannon and splint bones are most likely to be a splint. The expression splint is largely used to describe a condition known as interosseous desmitis, however there are various factors that can cause splints.
Inter referring to Between
Osseous referring to Bone
Desmitis referring to the inflammation of ligament tissue
Keeping your horses’ legs healthy is essential, as the limbs are structured in such a fashion that they act as an extremely extravagant shock-absorbing system. A majority of the animal’s weight load is placed on the front legs, which is an estimated 60-65%, with the remaining on the hind legs. The horse’s front legs are not connected to the main portion of the horse’s skeletal system, mainly held in position by a girdle of muscles, which can be described like a sling. Splints are more likely to occur when the horse’s weight-bearing structure is strained and under duress or can be the result of conformational faults. Causations of splints can be from several conditions and activities, such as a poor diet, trauma, excessive workloads and poor confirmation. Splints are repeatedly seen in young horses due the elasticity of the small interosseous ligament, which later fuses the splint bone to the cannon bone.
Anatomy & Function of the Splint Bone
To understand the functionality of splint bones, it is necessary to remember the horses’ prehistoric ancestors which had multiple toes, however through evolutionary process horses now walk on a singular digit (metacarpal/metatarsal I). These remaining digits (metacarpal/metatarsal II & IIII) are still present within the horse’s limbs but have undergone monumental changes to become splint bones. Metacarpal III is commonly known as the cannon bone.
Splint bones are rudimentary metacarpal (forelimb) or metatarsal (hindlimb) bones that are located both laterally and medially to the cannon bone. Tapering down almost two-thirds of the cannon bone, the splint bone’s true function is vestigial meaning the bone has no apparent function like once it previously did for past ancestors. Splint bone’s still have kinesiological functions that fundamentally act as supports to the carpal and tarsal bones as well as the hock, this additional support allows for the extensive freedom of movement.
The splint bone forms a connection between the cannon bone with dense fibrous tissue called the small interosseous ligament. This Ligament is also known as the suspensory ligament and contains nerve receptors that alert the horses body to identify pain from an injury which was caused damage or inflammation. Therefore, injuries to this area on a horse can be extremely painful. Also see our article on horse hoof pain.
Saucer Fractures in Horse
Saucer Fractures can also be referred to as sore shins or bucked shins, that can arise when a horse experiences high levels of exertion whilst being worked or as a result of being exposed to hard and uneven surfaces when they are not fully conditioned. Generally, horses that experience Saucer fractures feel extreme pain due to the extensive inflammation of the connective tissues on the cannon bones. The result of intensified training can cause micro fractures within the cortex of the cannon bone, which can eventuate to major fractures if they are left untreated. The stress on the cannon bone reacts by trying to form new bone over the destabilised area, which is a natural response to reinforce the cannon bone. Bucked shins can also be associated with sore shins which in severe cases, will gradually form a large callous on the front of the cannon bone. The horse will usually be impacted by lameness with a shortened stride.
Horse Bone Splint
From a clinical perspective, splints occur in horses up to the age of seven, when the small interosseous ligament between the splint bone and the cannon bone becomes inflamed. The ligament can sprain or be torn by intensive work or a direct knock to the horse’s leg. The inflammation causes proliferative bone growth, which is the process of bone formation known as ossification.
Bones are coated with a thin membrane known as the periosteum. This membrane protects the bone and is utilised as the attachment for the ligament. The membrane is also responsible for containing cells that encourage the growth, development and repair of bones. These cells are responsible for the proliferation of bone, due to the increased blood supply and inflammatory response. The main concern associated with splints is generally cosmetic, however there can be severe repercussions that can result in secondary complications to the splint. It is rare for horses over the age of 8 years to develop a fresh splint due to the ligament becoming calcified, reducing its elasticity.
True splints in horses
Another form of splint, is known as a True splint. These types of splints revolve around trauma to the small interosseous ligament. Damage to the ligament can be varied, anywhere from a minor strain to a full force tear. The inflammatory response leads to edema, which is swelling due to excess fluid that is trapped within body tissues. Proliferation occurs to stabilise the area which is what causes the bony growth on the horse’s leg. The size of the bump is related to the original trauma. Commonly, True splints are found on the medial splint bone and can occur due to conformational issues, such as incorrect farrier work that leaves the animal unbalanced as well as surplus calories, dietary deficiencies, as well as excess weight from either rider or the horse.
A blind splint is the least common splint and usually occurs from associated damage to the small interosseous ligament adjacent to the medial splint bone. It results in a fibrous enlargement between the splint bone and the small interosseous ligament. This deep injury, is not normally associated with inflammation. The common symptom is lameness and to diagnose a blind splint commonly involves ultrasound, nerve blocks, and an area specific anesthesia.
A knee splint refers to bony swelling proximally in the splint bone, towards the knee. It commonly involves the lower part of the horse’s knee joint and can result in osteoarthritis.
Periostitis of the splint bone
Periostitis is the layering around the bone and when there is direct trauma to the splint bone the periostitis becomes damaged and soft tissue inflammation takes place and as a result causes the periostitis to come off the bone and to fill the open space with new bone proliferation. Periostitis of the splint bone can be on either the lateral splint bone or the medial splint bone.
Fracture of the splint bones
Direct external trauma is the frequent causation of a fracture along the splint bone. Diagnosis and prognosis of splint bone fractures are reliant upon the location. Fractures that are located to the lower end of the cannon bone can be tricky to manage without going down the pathway of surgery. Fractured fragments can be known to move; therefore, new bone formation can be delayed. Fractures that are proximal of the cannon bone can be challenging. Equine clinicians can be reserved about removing bone that is relatively close to the joint as it can cause future complications such as joint instability. Fractures that are located in the centre of the cannon bone are relatively straightforward.
Fractured Splint Bone Treatment
Fractured splint bones, can require surgery based on the locality of the fracture. The location of the fracture can be diagnosed via ultrasound and radiography of the splint bone and the interosseous ligament. The diagnosis of the fracture enables the veterinarian the opportunity to structure a rehabilitation program around the individual injury. Based on the location of the fracture determines the treatment of choice, whether that be either a surgical or medical attempt. Surgical removal of the fractures are commonly seen in horses that sustain a fracture in the proximal quadrant of the cannon bone, as this can cause future instability to the carpal bone. Prognosis is based on the individual cased and the associated damage caused by interosseous desmitis, which can have a greater impact on the horse than the splint itself.
Best treatment for splints in horses
Depending on the veterinarian, the majority of cases that involve splints treatment is based around anti-inflammatory therapy and other medications that counteract the animals natural healing response of bone proliferation. Modern technologies in veterinary medicine, have allowed owners to treat horse splints with Commonly Non-Steroidal Anti-Inflammatory Drugs are prescribed such as Bute. Topical Anti inflammatories ointments may also provide relief for most horses and stop further irritation. The injection of corticosteroids may reduce inflammation. It is normally recommended that horses be rested for at least four weeks on a soft surface. Some cases, do not require medical or surgical intervention however, it is always recommended to make contact with your equine vet before a decision is made not to persue medical and/or surgical treatment.
The prognosis for a large percentage of horses is exceptional, nevertheless prognosis can be implicated by cases that have large new bone growths or in the knee joint. At home, owners can implement hydrotherapy and cryotherapy to the area to reduce inflammation. Cold therapies can be applied multiple times throughout the day until the swelling has resolved, such as cold hosing. Pressure wraps are also used to treat splints, wraps improve circulation and promote healing to the impacted area.
Alternative treatments such as laser, ultrasound and shockwave therapy can increase the speed of healing, by stimulating new blood vessels. Pulsed Electromagnetic Therapy is an alternative non-invasive therapy which applies a magnetic field to the cells within the horse’s body. The impulses interact with the ions present within specific cells, accelerating activity and expediting the flow of oxygen and nutrients to the compromised area. PEMF therapy can assist in both kick starting and boosting the healing process at a cellular level, whilst simultaneously accelerating the disposal of toxins and waste products.
Can horses get splints on hind legs
Horses have carpal bones in all four limbs, so therefore it is possible for splints to form on any of the four legs. However, due to the horse’s suspensory system and weight baring structure, it is far more common for veterinarians to see splints form on the front legs.
How to prevent splints in horses
Splints can be prevented by conditioning your horse progressively on soft ground, especially with a young horse to allow their body’s time to adjust accordingly. Conditioning includes a consistent warm up and cool down for your horse’s leg. Protection of your horses’ legs with splint boots is another way to reduce the risk of a splint appearing. It’s also important to employ a farrier, who follows a regular appointment of trimming and/or shoeing and can maintain balanced hooves. It is encouraged that horses follow a diet that has a steady ratio between calcium to phosphorus to encourage bone development. It is also best to reduce the stress on bones and suspensory ligament by making sure the horse is not overweight.
How long do splints take to heal in horses?
Splints are not a quick fix solution, but it is to be said that early detection can significantly contribute to a positive prognosis. Variations depending on the severity of the splint controls the time it takes to heal. It can be multiple weeks and up to months on the side lines to wait for the splint to subside. Returning your horse early to work can result in further bony enlargements and so is strongly discouraged.
Can you jump a horse with splints?
Usually, a healed splint is not detrimental to a horse’s performance career. After the acute inflammatory phase and the initial healing period, horses are normally left with a cosmetic blemish. In regards to jumping, the causation of the splint should be investigated, to prevent further injury. That can mean changing boots to something more protective if the animal has a tendency to interfere.
Splints in horses are extremely common and usually subside after treatment. Splints can be seen in horses of all ages; however, it is far more likely that horses under the age of eight are to be impacted with the injury. Splints can occur as a result of direct trauma, poor conformation and nutritional deficiencies and owners should avoid overworking young horses.
Treatment plans are recommended to be followed and generally include minimal exercise ( a treadmill or walker is suitable), rest, anti-inflammatory medication and other assisted therapies. Surgery in extreme cases can be a necessity. It is always recommended to speak to your veterinarian as each case is different and they can form an accurate diagnosis that allows for the fastest recovery with the least number of complications.
If you have a horse who has been diagnosed with splints and want to find some treatment methods to help them you can explore our range of therapy options for your performance horse here and help them to perform at their best.
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Also be sure to check out our article on treatment options for arthritis in horses.