The hock is not a simple joint. Rather, it consists of several different joints. The uppermost and the largest of these is the tarsocrural joint, or the true hock, and this is where most of the joint’s flexion takes place. Adjacent to this joint is the calcaneus bone, which forms the point of the hock. Below the tarsocrural joint are three smaller joints in which occur very little motion.
A good hindlimb and joint anatomy chart will illustrate all the details of this complicated joint. Visit the Gladstone Equine library for books that provide more extensive information on hock conditions.
- Bog Spavin: Swelling of the talocrural or the upper, main joint in the hock.
- Bone Spavin One of the most common causes of lameness in the hind legs.
- Capped Hock: Usually caused by the horse’s kicking a solid structure.
- Luxations and Fractures: dislocations of the hock are relatively common.
og Spavin is characterized by swelling of the tarsocrural or the upper, main joint in the hock. Unlike Bone Spavin, this condition usually occurs in younger horses, showing up at six months to two years of age. The condition usually results from Osteochondritis dissecans (OCD) or subchondral bone cysts. OCD, the genesis of which is unknown, is characterized by large flaps of cartilage or the presence of loose cartilaginous bodies. Some authorities theorize that the condition is caused by nutritional factors.
Other causes of Bog Spavin can be trauma and poor conformation. It seems that horses with straight hocks seem more likely to develop Bog Spavin and most likely to carry the swelling for their entire lives. Degree of lameness will vary, and in many cases, the animal may not be lame at all.
Visit the Gladstone Equine library for books that provide more extensive information on bog spavin. There is also an excellent anatomy chart that illustrates general hind limb and joint anatomy as well as a specific hind leg conformation chart.
Swelling in the hock joint is the main characteristic of Bog Spavin. The swelling has a predictable appearance: A soft, movable swelling on the inside front portion of the hock, and another, slightly higher on the outside of the hock. If one of these swellings is compressed, the other will expand proportionally since both swellings are out-pouchings of the same bursar sac.
Your veterinarian will have to examine the animal in order to determine if OCD is evident. Treatment of this condition depends on the cause. If OCD is present, removal of the cartilage via arthroscopy should be considered; your vet can make that determination. If there is no OCD, then the goal is to reduce the swelling, and the best ways to achieve this are by means of Hydrotherapy, Acupuncture – Acupressure, and Low Energy Photo Therapy (LEPT), which is an excellent means to reduce swelling through increased vascularity and circulation.
Bone Spavin is the common term for secondary joint disease or osteoarthritis of the hock, and is one of the most common causes of lameness in the hind legs. Usually, the three lower, less movable, joints are the ones that are affected. The disease usually occurs in older performance horses such as Standardbred racers, western performance horses, jumpers and polo horses.
Since the disease is most often bi-lateral, which is to say that it occurs in both legs at the same time, it most commonly presents itself as a general stiffness in the gait. As with humans suffering from arthritis, joint stiffness will be most pronounced in the morning or when first coming out of the stable and will ease during exercise. Swelling on the inside of the hock and uneven wear in the shoes are also useful clues. It will be helpful to review a good hind limb and joint anatomy chart to understand the exact physiology of the hock joint.
As with any disorder, it’s advisable to consult with your veterinarian. Since this hock condition begins in the cartilage before degenerating to the bone, and cartilage can’t be seen in x-rays, a radiograph can rule it in during the early stages, but not out. As the bone spavin disease progresses, the space between the bones will become smaller and eventually the smooth edges of the bone will become fuzzy and bone spurs will appear as the body begins to grow new bone to bridge the gaps where the cartilage has disappeared.
The biggest problem with bone spavin is that it hurts. In most cases, the condition will resolve itself: as the disease progresses, the cartilage will completely deteriorate and the bones will fuse. You can see complete fusion in the x-ray shown above. As long as the three lower joints are the only ones involved (which is most common) the horse will eventually regain soundness. Visit the Gladstone Equine library for books that provide more extensive information on bone spavin.
But the question remains: What do you do for the pain and lameness inherent in a bone spavin condition? You can treat with anti-inflammatories and rest the animal, but that will only prolong the disease.
He needs to be exercised, in order to keep up good muscle tone that will support the joint, and exercise also helps work the joint to keep it warmed up and lubricated. He needs to be monitored by the vet as the condition progresses, and he needs to be properly shod. Since you’re on this website, you know that all horse owners should have a therapy team consisting of the vet, farrier and complimentary therapists.
Capped Hock is a casual term for a hock condition that according to Mordechai Siegal of UC Davis School of Veterinary Medicine, “describes a traumatic bursitis over the point of the hock, usually caused by the horse’s kicking a solid structure.”
That means your horse has a big ugly swelling on the point of his hock. It usually looks worse than it really is. Visit the Gladstone Equine library for books that provide more extensive information on capped hock conditions, and it’s also an excellent idea to consult a good anatomy chart so you can understand just what’s going on with your horse’s leg.
This is generally not a serious hock condition in that it doesn’t threaten permanent lameness, but a veterinary exam is always a good idea in order to rule out a more severe injury. The main concerns with a capped hock are alleviate pain, reduce swelling, and prevent further injury.
Hock Luxation and Fracture
The final Hock Conditions that we address are Luxations and Fractures. Luxations are actually dislocations, and dislocations of the hock are relatively common occurrences. They’re often caused by tangling the leg in a fence or from a kick by another horse. If your horse has dislocated his hock, call the vet. He’ll want to x-ray the area to determine the extent of the injury and recommend treatment.
The same also goes for fractures, and this is why we always recommend that you have a vet examine any onset of lameness. Otherwise, how would you know if your horse sprained his hock or fractured the end of his tibia?
Correction of a simple Luxation of one of the lower hock joints without the presence of a fracture is fairly straightforward. The vet puts the horse under anesthesia and the dislocation is corrected. If the dislocation is in the upper joint, your vet may choose to employ a long cast to stabilize the structures until they heal.
Generally, a horse experiencing a luxation with no fracture should recover completely. However, the prognosis for fractures of the tarsal bones is generally unfavorable and full recovery without permanent lameness is questionable. Visit the Gladstone Equine library for books that provide more extensive information on Hock Luxation and fractures
In addition to these standard methods for correcting the hock condition, complementary therapies will give the horse a better chance for complete recovery. As we have shown previously, reliable treatments include cold Hydrotherapy, Application of anti-inflammatory medications, use of pressure bandages, Acupuncture – Acupressure, and, Low Energy Photo Therapy (LEPT), which is an excellent means of reducing swelling through increased vascularity and circulation.
LEPT raises the levels of Nitrous Oxide in the area of treatment. Clinical studies by medical schools independent research organizations and Government institutions Have confirmed that increases in nitric oxide are required in the healing process, in that they allow nerve synapses to communicate more efficiently, ultimately creating increased circulation and lymphatic flow.
Magnetic therapy has also been promoted as a useful modality, but we have not seen any clinical evidence to sustain those claims. If you are aware of any scientific studies that support the efficacy of magnetic therapy, please let us know about them.