Updated: Mar 13
The fracture of a splint bone in a horse is a reasonably common occurrence. The splint bone plays an important role in the support and stability of the knees and hocks. Therefore it is important that all fractures involving the splint bone are treated immediately.
The Causes of Splint Bones Fractures:
The fractures of the bottom third of the splint bone are what is the most common and they are usually the result of internal trauma by the over-extending of the fetlock joint. This trauma will occur when the affected leg is fully weight-bearing and the fetlock is at its lowest point of the horse's stride.
This results in stress being placed on the bone, between the attachments to the cannon bone at the one end and the attachments to the fetlock at the other end. These fractures will usually occur in horses at around 5 to 8 years of age when the splint bone has lost some of its flexibility.
The strain of the suspensory ligament will often occur hand in hand with these bottom-third fractures because similar stress is being placed on the ligament.
Another possible way that the splint bone will break is when the suspensory strain will be what causes the splint bone to fracture as the injured suspensory ligament will push the splint bones outwards during the flexion of the fetlock.
Conformation, which can lead to interference, will predispose a horse to fracture its inside splint bones. An excellent example is knocked-kneed horses where the limb angles outwards below the knee. Horses with unbalanced feet (where the inside and outside hoof walls are different lengths ) may be more likely to suffer lower splint fractures.
The Warning Signs Of A Fracture:
Look for swelling over the inside and/or outside of the cannon bone, pain to the touch, heat, and lameness which are all signs that a splint bone may have been fractured.
Simple fracture lameness isn’t always noticeable in a straight-line trot, where lunging or faster work may be required to detect any lameness.
Diagnosing A Splint Bone Fracture:
The signs of a splint bone fracture, as described above, will suggest a fracture may have happened. X-rays will need to be taken to give a positive diagnosis of the injury.
An ultrasound scan should also be done to see if there is any suspensory ligament damage that may have occurred at the same time as the fracture of the bottom third of the splint bone.
The Treatment Of The Injury:
If there is an obvious swelling of the leg when the initial injury occurs, place ice on the area for twenty minutes before placing a very well-padded pressure bandage over the area until your vet can examine your horse. Also, on the advice of your veterinarian, administer an inflammatory drug, such as phenylbutazone (bute), to assist in decreasing the swelling.
Low fractures: The usual treatment for bottom third fractures is to surgically remove the broken bottom piece of bone and round off the end of the remaining portion. This is still the most preferred way of treating this type of fracture in most cases. This allows the horse to be back to work fairly quickly after surgery. In most of these cases, there is no suspensory injury.
If the fractured portion of bone is not displaced and is stable, then stall rest along with a pressure bandage will heal the injury perfectly. The recovery period will be a bit longer for the horse with this treatment.
Higher fractures: The more complicated fractures that involve the upper third of the splint bone will require surgery to repair the top portion of the splint bone in place so that downwards pressure from the knee or hock does not cause continual movement of the splint bone, which will cause irritation and increased lameness. This is achieved by using stainless steel screws - which attach the splint bone to the cannon bone - or sometimes a combination of screws along with a steel plate will be used.
If there is an open wound over the fractured area, the wound and bone often become infected. Therefore, treatment with antibiotics and antibiotic dressings is necessary to control the infection before any surgery can take place. If the horse is given the proper amount of time, these fractures could possibly heal themselves and surgery may not even be necessary.
Your Horse's Recovery:
After the treatment is completed, the chances of your horse returning to its previous level of work are usually very good. If the suspensory ligament has also been strained, then the "off time" will be much longer, possibly many months, and there is a higher likelihood of lameness reoccurring to their suspensory ligament.
When starting a horse back to work again their exercise needs to be built up gradually. Start with just walking your horse twice per day and then slowly working up from there.
Recap - Immediate Action:
If you suspect that your horse has a fractured splint bone, then follow this three-step procedure:
Put your horse in its stall and restrict their movement.
If your horse has an open cut or wound, clean it, dress it then put a pressure bandage on its leg.
Call your veterinarian to assess the horse's situation.