Fracture of the hock joint can be a career ending injury in a racing greyhound. Statistics indicate that as few as 40% of greyhounds with fracture of the hock joint return to the race track and probably only half of these continue on racing at the class in which they raced prior to the injury.
However, over the years, experience in surgical repair techniques and physiotherapy of the hock joint during the healing process has increased the likelihood of a successful return to an active lifestyle in retirement as well and an improved rate of return to racing.
In the first 2 parts of this series on hock injuries in greyhounds, I have discussed ‘wear and tear’ type injuries and internal ligament injuries within the hock joint.
The emphasis in all bone or joint injuries affecting a racing greyhound is to access the degree of damage as quickly as possible and apply ice and a pressure or support wrap to the limb above, over and below the injured joint to reduce the risk of further damage to the joint until you can obtain expert advice from your vet.
The greyhound must be confined and kept as comfortable as possible, taking care not to aggravate the injury when lifting the greyhound into its bed or into a vehicle for transport to a vet.
In some cases, more severe damage can occur if the limb or joint is over-flexed inadvertently when attempting to move or transport the animal.
Fractures of the Hock
The hock joint is considered to be the most complex of all the lower limb joints.
The late Dr Jim Gannon, a world renowned Australian greyhound specialist vet, points out in his writings that not only are there seven bones which form the flexible hock joint, but these also articulate with the lower ends of the tibia and fibula bones of the upper limb and with the four metatarsal or ‘shin’ bones of the lower leg.
This results in 4 separate joints within the hock to provide the movement and flexion required during exercise.
Fracture or dislocation of the central tarsal bone in the right hock, often with ‘popping’ of the bone out from its position, is most common on a poorly banked turn with a shifting surface.
The right limb is subjected to high compressive forces and rotation as the greyhounds turns to the left at speed.
This is a common injury, often occurring when a greyhound loses its grip on the track surface, the track surface shears under the foot or the greyhound is bumped or suddenly checked on a turn.
The severity of the fracture depends on the number of separation areas in the central tarsal bone, with single or double fractures within the bone being the most common.
In severe cases, the bone may break into a number of pieces.
This usually is a less likely fracture to repair without arthritic changes and reduced flexion of the hock, with a risk of reduced movement and repeat fractures.
In most cases, a shattered hock results in retirement from racing.
The risk of hock fractures is also related to the conformation of the greyhound.
Greyhounds with small or excessively bent hocks are more likely to suffer from central tarsal bone fracture and dislocation as they gallop around tight bends, whereas greyhounds with more upright hocks are more prone to concussive damage and often internal ligament tearing when turning on a tight, poorly banked or loose surface.
However, this is not a definite rule, as both types of poor conformation can develop the same location and severity of hock fracture.
Ideally a greyhound with a weak conformation of the hocks, especially if it is the possible underlying cause of a hock fracture, should not be retired to breed.
In these cases, retirement as a pet is the best option.
If the decision is made at the time of examination by your vet, then simple stabilisation of the multi-fractured hock with a cast rather than expensive repair surgery is worthwhile.
But special care should be taken to avoid the animal shifting weight onto the hock joint as it repairs is essential to avoid severe bony reactions and instability within the hock.
In some severe cases, the blood supply to the hock fracture site may be compromised and the rate of healing slow and complicated.
Management of Hock Fractures
It is beyond the scope of this article to describe the management and surgical repair options for the various degrees of hock fracture.
This should be left to your vet or experienced greyhound orthopaedic surgeon to access the fracture type and severity and decide on the most appropriate form of stabilisation and aftercare.
If a greyhound has good form and racing talent, then surgical repair with screws is the most successful way of managing any single or double hock bone fracture to enable the greyhound to return to racing.
Some veterinarians have had success in stabilising a fracture or dislocation of the central tarsal bone by applying a strong rubber sleeve over the hock joint to hold the healing bones in their correct positions.
This, when combined with confinement and later physiotherapy to encourage passive flexion during the healing phase, can be a successful lower cost option to surgery.
In some cases, this technique is less likely to result in complications as can occur under a cast, especially where blood supply to the healing site is less than normal.
X-rays taken of the hock after the initial swelling has subsided under an ice pack and pressure/ support bandage, ideally within a couple of hours to evaluate the severity, position and other complications, such as 2 separate fracture sites, which can occur in the right hock in particular.
After Injury Repair
The hock joint is a joint which has to be able to flex when loaded and withstand high rotational forces, both when racing on a circle track and when turning suddenly during coursing, as well as responding to acceleration and braking during a race or course.
This requires that a rehabilitated joint must still retain its full flexion and movement, without discomfort and pain.
Over recent years a number of glucosamine joint active supplements have become available to help the function and health of all joints with minor arthritic changes and pain after exercise.
The hock joints and wrists are the joints most likely to have the higher risk of arthritic change following injury, and particularly due to internal fracture of bones or ligament sprains or tears within the joint.
The benefit of these supplements, even in humans to provide improved joint flexion and relief of minor discomfort, varies greatly relative to the formulation, dose rate and the length of the supplementary course.
Generally, joint supplements need to be given at an initial loading dose for up to 2-4 weeks, usually as twice a day doses, and then stepped back to a once daily maintenance dose to help the function of the joint cartilage surface.
This can be combined with supplementary calcium for subchondral bone strength under the joint cartilage layer on the ends of the limb bones.
The newer products contain glycosaminoglycan compounds (GAGs), such as hyaluronic acid, along with manganese and vitamin C which assist cartilage rehabilitation.
In severe cases, your vet may recommend a course of intra-articular cortisone, although excessive amounts can result in calcification of joint surfaces in the long term, combined with in feed GAG compounds.
If you have a greyhound which has suffered a wrist or hock injury, then discuss these aids to joint surface rehabilitation with your vet.
Magnetic field therapy, especially in a cage unit, is also beneficial to promote blood flow in damaged joints, particularly during the repair period following a fracture.
