When a greyhound appears to have suffered a hock injury by the way it walks or pulls up after a race with the affected limb held off the ground, without any obvious swelling, then careful examination is required to confirm whether the injury is a primary hock injury or in the limb just above or below the hock.
Hock injuries can range from minor internal ligament sprains with swelling, discomfort and increased joint fluid to an acute injury involving fracture or displacement of the central tarsal bone, often referred to as ‘popping the hock’.
This severe type of injury occurs most often when cornering on a loose surface or a when a greyhound is bumped and put off the line of a gallop on a tight track. In the long term, both of these injuries can lead to arthritic change and reduced flexion or ability to bend the joint.
Obviously, a greyhound which ‘pops’ a hock in a race, will pull up on three legs after the race, with acute pain and rapid swelling of the hock joint.
However, minor internal sprain injuries may be missed in an early case, but if the greyhound continues to race, more severe damage and obvious symptoms will be apparent and require longer term therapy and management.
Loss of Flexion
Several years ago, in a review of common hock injuries, the late Dr. Jim Gannon of the Sandown Veterinary Clinic in Melbourne, Australia, discussed the signs and therapies for restricted hock movement.
Dr Gannon observed over his many years of examining greyhounds, that most can cope with minor hock discomfort, but if the arthritic change continues to deteriorate, they will then begin to exhibit signs of reduced hock flexion when the hind limb is lifted and flexed to put pressure on the hock joint.
Even in cases where flexion is markedly reduced and pain and withdrawal is shown, there is often no obvious swelling around the hock joint itself.
However, if the hock joint and adjacent hind limb muscles are carefully viewed from the rear and compared with the adjacent hock joint, often a loss of muscle mass is apparent in the ‘calf’ muscles over the Achilles’ tendon.
Affected greyhounds may drift-out wide on the turns, or slow down when cornering, particularly on a sand track with a loose or chopped up surface on the corners, but run to form up the straights.
As the hocks are important for the spring action of the back and hind limbs to catapult the greyhound from the traps at the race start, greyhounds with a hock injury will often develop a lower, flatter jump from the boxes, losing valuable speed and up to 2-3 lengths at least out of the traps.
The primary cause can be due to a previous, or recent minor fracture of one or more of the small bones which form the hock joint, which is similar to the human ankle. These injuries usually result in swelling and inflammation within the hock joint and pain on flexion.
Other Lower Limb Injuries
In greyhounds, a loss of flexion of the hock can also be secondary to fracture of one or more of the thin metatarsal (‘quarter’ or ‘shin’ bones) of the rear limb below the hock joint.
Often these injuries do not cause swelling at the level of the hock joint, but show as discomfort with withdrawal of the limb or a yelp when the metatarsal area is gently squeezed in the hand or manipulated with the fingers.
Other injuries in the lower limb, including fracture of the small sesamoid bones on the bottom of the toe joints, or strain of the sesamoid ligaments, can also cause discomfort and pain on manipulation of the affected joint.
These greyhounds are often reluctant to bend the hock joint or bear weight at the gallop.
Other signs include a reduced stride length and speed and they often pull up after a gallop with the hock joint flexed to take the weight off the lower foot area.
Although these symptoms can be confused with a primary hock injury, usually the hock joint can be fully flexed when standing with the limb held up, with no apparent discomfort.
Strain or internal tearing of the achilles tendon, or the three muscles which combine to form this ligament attachment to the point of the hock, can result in reduced flexion and discomfort when the hock is manipulated.
Even a ‘track leg’ or ‘Jack’ caused by the elbow hitting and bruising the area on the inside of the tibia bone just above the hock, may show some of the symptoms of pain and reduced flexion of the hock joint until the soft ‘haematoma’ swelling appears at the track leg site within a few hours after a race.
A broken or bruised thin section of the fibula bone in a young greyhound, usually located under the prominent saphenous vein on the outside of the left hind limb just above the hock, may also exhibit initially as swelling and reluctance to flex the hock when examined once the greyhound cools down after a race.
Pressing lightly on the area over the saphenous vein for 10 seconds and then walking the greyhound off will usually cause discomfort and help diagnose a fibula fracture, even before a small bone lump or callous develops as the fractured bone attempts to heal between races.
First Aid is Essential
In an obvious case where a greyhound pulls up on three legs with acute hock swelling where the central tarsal bone has ‘popped’, the displaced bone must be attended to promptly with appropriate first aid.
The hock must be iced for 2-3 minutes on the inside of the joint over the swelling and wrapped in an elastic bandage and referred to your vet for an X-ray and prompt treatment. In most cases, because the injury is acute and the symptoms easy to recognise, the trackside veterinarian will usually apply icing under an elastic pressure bandage as an initial form of first aid.
Once the swelling is reduced after 3-4 minutes, an elastic conforming bandage is best applied to support the joint and keep the bones within their normal relationships until the degree of injury can be assessed by careful examination and an X-ray of the joint.
Although therapy to reposition the displaced central tarsal bone can vary from elastic bands to repositioning the ‘popped’ bone during the time it takes to repair, to more extensive surgical correction, the treatment has to be carried out as soon as possible to avoid further devitalisation of the bone and development of severe bone reaction and osteoarthritis in the joint.
Where a greyhound only exhibits a mild degree of reduced flexion of the hock, especially when there is no obvious swelling, it is important to refer the greyhound to your vet for a careful examination of the metatarsals, sesamoid bones and ligaments, and the achilles tendon and its associated muscles. It is also wise to examine the track leg area on the inside just above the hock or for a fibula fracture on the outside of the limb above the hock.
If inflammation is present over a bone surface, such as the metatarsals, then your vet will normally take an X-ray to determine the degree of bone surface reaction (called periostitis) or actual fracture of a bone or bones.
However, the type of therapy and management is similar for ligament strains or mild fractures when combined with an adequate rest period ranging from 2-4 weeks relative to the location, type and degree of the injury.
In Part 2, we will discuss other supportive therapy for hock and ‘look alike’ lower limb injuries.
