From Horse and Rider - UK JAN. 2016
MAKE OR BREAK
Modern veterinary techniques are making fractures in horses ever more treatable. Vet Suzy Hall from Liphook Equine Hospital explains
Suzy Hall BVetMed MRCVS
graduated from the Royal Veterinary College in 2010. She joined Redwings Horse Sanctuary in Norfolk before moving into private equine practice in Kent. She joined Liphook Equine Hospital in March 2013.
In the past, the diagnosis of a fracture left very few options for the future of the affected horse, with most cases having to be put to sleep. But thanks to recent advances in equine fracture treatment, the prognosis for certain fractures has improved greatly, meaning that many horses can now be saved, and the number of horses recovering from fractures is continually increasing.
The low-down on bone
Bone is the third hardest substance in the body behind enamel and dentin (found in teeth). It is responsible for the protection of vital organs and provides structure to the body, facilitating attachment muscles to generate forces and allow movement. It is also the largest reservoir of calcium and phosphate in the body. There are two broad types of bone - cancellous and cortical bone. Cortical bone is in the shaft of long bones whereas cancellous bone occupies the cavities within the bone.
Bone is dynamic and undergoes constant renewal through a remodelling process, influenced by the stresses and strains placed on the skeleton during exercise. It is unique in that it can repair itself without a scar following fracture.
How to spot a fracture
Areas where bone is immediately underlying the skin, such as the scapular spine (the long ridge that runs down the outer side of the scapula) or the major tubercle of the humerus (a prominent ridge at the top of the bone) are particularly vulnerable to fracture, so bear this in mind when you're checking your horse for possible bone damage.
The most common clinical sign of a fracture is acute or sudden onset of severe lameness. There may also be an overlying wound, perhaps a kick wound. If you suspect a fracture, check the whole leg and feel for any areas of swelling or instability. If the leg is unstable, it is important to keep your horse as still and calm as possible to prevent further soft tissue damage that may be caused by bone fragments moving in the muscle.
Keeping your horse settled with feed or having other horses nearby may help to keep him calm while you're waiting for the vet. Trying to add external support to the leg may distress your horse further, so it is best to wait for your vet before attempting this. If you're in any doubt, always treat and handle your horse as a fracture patient until this can be ruled out, as some fractures can easily be overlooked.
Confirming the problem
Any injury that is associated with severe lameness should raise suspicion of a fracture if no other apparent cause of lameness can be found. However, other causes of sudden, non-weight bearing lameness include foot abscesses and infection of a synovial structure in a joint.
When your vet examines your horse, they will feel the area for any signs of heat or swelling that may indicate the cause of the lameness. Feeling bone crepitus (loose bone) under the skin can suggest the possibility of fracture.
To rule out a fracture, your vet may take X-rays, which with modern radiography equipment is now possible in your horse's field. However, non-displaced or incomplete fractures are extremely difficult to diagnose immediately following the incident, because although the bone has fractured, the two pieces of bone sit close to one another. This means that the fracture line isn't visible on X-ray.
In these cases, it may be necessary to repeat X-rays several days later, as it can take up to 14 days for a gap in the bone to be shown on X-rays. Alternatively, other specialist imaging techniques, such as ultrasonography, nuclear scintigraphy (bone scan), magnetic resonance imaging (MRI) and computed tomography (CT), can be used to diagnose a non-displaced or incomplete fracture in the early days.
Ask a vet
How bad is the break?
The severity of the fracture is determined by whether or not the skeleton becomes unstable. To understand why fracture of the long bones of the limbs in horses is so serious, we must first consider how the fracture occurred. When a horse is galloping, during each stride a single leg takes the whole weight of the horse. If a fracture occurs at speed, it tends to be explosive in nature and results in severe communition or breakage of the bone, causing extreme soft tissue damage. Technically, it may be impossible to restore the integrity of bone and soft tissue after such an injury.
With fractures of long bones, if the nature of the fracture allows surgical fixation of the bone then the method must be strong enough to withstand huge mechanical loads. The fixation is tested immediately post-surgery in the recovery period, when the horse has to stand following anaesthesia.
Some fractures don't lead to skeletal instability, such as fracture of the splint bone or pedal bone. In these cases, horses may not require surgery and just a period of box rest may be warranted.
Fractures of the pelvis and femur can be life-threatening due to the anatomy in this region. Large blood vessels sit in close proximity to these bones and a fracture of this region can lead to severe haemorrhage if a blood vessel is damaged by the bone fracture ends. However, fractures of the pelvis may heal with time and the horse may go on to return to normal athletic function.
Stabilizing the injury
If your vet has diagnosed a fracture that requires surgical correction, the most important part of their initial treatment will be to stabilize the limb to prevent catastrophic injury from occurring. The goals of stabilization are to reduce pain and anxiety to your horse, and allow partial weight-bearing of the limb and immobilization of the adjacent joints. Your vet will use a Robert Jones bandage (a multi-layered dressing that will double the circumference of the limb in order to provide support), splints or casting material in order to achieve this. Giving your horse support will make him more comfortable and less likely to cause severe injury to himself, until permanent surgical fixation can be carried out.
Region 1 contains the hoof up to the lower cannon region. This includes the foot, pastern bones and the distal sesamoid bone or navicular bone. Fractures of this region can be stabilized with a cast or splint.
Region 2 is from the lower cannon to above the knee in the forelimb and below the hock in the hindlimb. Stabilization of this region requires support from the hoof to the elbow or stifle, often best achieved with a Robert Jones bandage.
Region 3 is up to the elbow or stifle and includes fractures of the radius and tibia. This region is very difficult to stabilize due to the large amount of muscle exerting forces on the bones, which can often lead to catastrophic injury occurring. Stabilization must include the whole leg if treatment is to be attempted. For example, the vet may apply a Robert Jones bandage with a splint on the inside of the leg and one on the outside that extends to the height of the withers.
Fractures of the ulna (point of the elbow) result in failure of the passive stay apparatus (the triceps muscle apparatus), which normally allows the horse to stand for long periods of time with very little effort. Fractures of this region mean the horse stands with a dropped elbow appearance and the knee knuckles forward. Splinting of the leg holds the leg in extension and allows the horse to weight-bear on the limb.
Region 4 Fractures of the humerus anD femur. It is impossible to support these bones as they cannot be adequately immobilized to prevent further tissue damage.
Fracture healing in the horse occurs at a slower pace than in most other animals, including humans
Equine bone reacts to trauma and fracture with active new bone formation and remodelling. Fracture healing in the horse occurs at a slower pace than in most other animals, including humans - it can take 12 weeks or more before healing is complete. It's thought this is because, in some areas of the body, the small amount of soft tissue surrounding the bone leads to slow healing. Plus, horses are unable to rest up and use crutches like we do, so because they have to bear full weight on the injury, there are enormous stresses on the repairing bone. Your vet may use X-rays to monitor the bone as it heals. The success of the healing process is completely dependent on the type of repair performed and the nature of the fracture. Complicating factors include wounds and soft tissue damage. If there is an associated infection at the fracture site, this will complicate and delay healing of that area. And fractures involving a joint may increase the chance of osteoarthritis forming in the joint in the future.
Bone is a highly vascular tissue with an excellent capacity for self-repair. Callous formation or new bone formation occurs with bone healing, and the more stable the fracture is, the less callous will develop. Bone can repair and become as strong as it was prior to fracture if the bone union is achieved successfully.
A positive future
Management of fractures in horses has been revolutionized in recent years. Anaesthesia is more controlled, and recovery from anaesthetic is safer with advances in facilities and anaesthetic drugs. Developments in surgical techniques mean that fracture repair is now possible in more regions of the body, and success rates are high. So with early diagnosis and correct management, happily most fractures in horses can be successfully treated.