If you have ever been around horses, you will be aware of the frequency with which horses injure themselves compared to other pets. This may be partly related to the flight rather than fight response horses have to certain situations. They also have a large body mass (often in excess of 500 kg) on a relatively thin support structure (limbs) which is poorly protected by muscle coverage. Horses are athletes and these factors combined, make severe injuries in the horse inevitable. Fractures represent a serious, potentially life-threatening injury in the horse.
Try not to panic, remaining calm is essential to help prevent further injury. The first thing you will notice is likely to be severe lameness. Your horse may be reluctant to put their foot to the ground and may be trembling and/or sweating in response to the pain. Put a headcollar onto the horse and try and keep them as still as possible. If your horse is outside leave him/her where they are and avoid walking the horse to a different location.
Fractures are often non-displaced at the time of injury, ie the bone fragments are still in alignment and excessive movement without sufficient support of the limb can cause these fragments to displace. This can cause transformation of a previously repairable injury into an irrepairable one. Have a good look all over the horse, do they have any other injuries? Large wounds can often divert the eye and appear to be the most severe injury whereas the lame leg probably has far greater implications for the horse and should take priority.
Unfortunately, in some catastrophic cases the limb may appear distorted and the fractured bone ends may penetrate the skin (open fracture). In either of these cases, euthanasia is always indicated. In any emergency situation involving your horse, contact your vet immediately.
Horses are often excitable following injury due to the inability to bear weight on all four limbs, therefore sedation may be required to examine the horse fully. Your vet will assess the extent of the injuries paying particular attention to the affected limb. A localised area of swelling, pain on palpation, muscular spasm and instability of the bony structures are indications that a fracture may be present.
Many equine practices now use portable digital radiography, if this is available, radiographs of the affected area can be performed immediately. If the horse needs walking to a power source or transportation to a referral hospital, the limb will be splinted to provide support.
Radiography (x-rays) is the main diagnostic imaging modality used in the diagnosis of fractures. Multiple views may be required to determine the extent of the injury. In some cases small, non-displaced fracture lines are impossible to visualise on radiography immediately following the injury. It can take up to two weeks for a fracture line to develop, therefore radiography may be repeated at a later date.
Fractures come in various types, shapes and severity. They can range from small, hairline cracks to the more serious spiral or comminuted (multiple fragments) configuration. An important consideration in horses is the inability for us to impose restricted weightbearing. In humans, they can lie in a bed with no weight on the limb for several weeks whilst the fragments heal. In horses this is not an option. Temperament is also an important consideration. Whatever the fracture type, a prolonged period of box rest will be required, its important to assess whether the horse is amenable to management during the healing period.
Equine orthopaedic surgery has advanced considerably over the years making fracture repair of the lower limb with metal implants possible in some cases. Surgery always involves general anaesthesia which carries potential risks, especially in the fracture case. Fractures above the carpus and hock generally have a hopeless prognosis and euthanasia is the only option. Pedal bone fractures in contrast are a common occurrence and generally heal well with a prolonged period of rest. Your vet will be able to advise you on the best treatment option and the potential outcome of your horse.
The aim of the healing period is to restrict movement of the bone ends in order for osteoclasts (bone removing cells) to eliminate bone debris whilst osteoblasts (bone-producing cells) lay down new bone. This process is termed bone-remodelling and is responsible for the formation of a bridging callous within the fracture gap. If the bone ends are constantly moving fracture repair will fail.
The horse will need to be kept in a stable, and may be cross-tied for a period of time. This is when a rope is attached to either side of the halter and the ropes are tied to a fixed object. This prevents the horse from lying down and importantly, getting up from lying down and exerting excessive force on the injured limb. The limb will be supported either in a cast, a splint, or a Robert Jones bandage. Repeat radiography will be used to assess healing.
- Failure to heal – this may be as a result of poor surgical failure, excessive movement or force on the bone ends or an inadequate blood supply to the affected area.
- Bandage/cast wounds – pressure sores can develop in response to prolonged bandaging. These can occur even when extra vigilance has been implemented in an attempt to avoid them.
- Sequestrum formation – this is when a small fragment of bone separates from the main bone structure and acts as a foreign body preventing wound healing or causing a draining infectious tract. Removal of the fragment is indicated if clinical signs persist.
- Laminitis – the constant additional mechanical load placed on the sound opposite limb makes them particularly susceptible to laminitic changes. Precautions should be implemented to avoid this occurrence deep bedding, sole supports and monitoring of digital pulses.
Fractures of the equine limb are every owner’s nightmare. Due to the size and nature of the horse, treatment is a constant challenge. Horses with severe fractures or fractures of the upper limb are not amenable to treatment and will be euthanased. If your horse does sustain a treatable fracture it is important to recognise that there will be considerable expense and time involved but some do make it back to full athletic function. Whatever the case, good communication between vet and owner is the key to success!