Hock Lameness in Horses: Causes, Symptoms, and Treatment Options

The hock joint is one of the important elements in allowing a horse’s movements to occur with such grace and agility.

The hock is also absorbing significant force from these movements. When the hock joint becomes repeatedly stressed, hock lameness in horses can develop. 

What Is Hock Lameness in Horses?

The hock’s anatomical name is the tarsus, and the hock in a horse is the equivalent to a human’s ankle joint.

The “hock joint” is a collective term referring to several joints and small bones that make up the hock. The hock is one of several key areas in the horse’s hind end that provides the driving force and forward motion, as well as maneuverability (think barrel racing, cutting, or showjumping disciplines).

When a horse exhibits pain from one or both hocks, some of the driving force will be lost. The horse also may not turn as well in one or both directions.

Inflammation of the joint capsule and excess joint fluid can cause swelling or “puffy hocks, also known as synovitis. If this inflammation continues for a prolonged time, then bony changes can start to occur.

The bone reacts to the inflammation by creating more bone that can interfere with the normal gliding motion of the joint. This can cause the horse pain upon flexing the joint in the airborne phase of the stride.  

Lameness of the hock is common—horses ridden for sport tend to put excess stress on the hock joint. The hind end and hocks provide a lot of the driving force for speed and jumping, as well as propulsion in collection.   

Horses that have poor conformation on the hind end (very upright or cow or sickle hocked) or horses that are ridden at a very high level of performance can be more susceptible to hock lameness.

Hock lameness is only a medical emergency if it is severe like a joint infection or fracture.

Symptoms of Hock Lameness in Horses

If you were to watch a horse with hock lameness move in a straight line away from you, you may notice asymmetry in movement of the hips at the trot.

Other indications of hock lameness include:

• Shortened stride in the hind end at any gait

• Stiffness

• Lack of engagement of the hind end

• Difficulty navigating hills

• Shifting weight on the back end or repeatedly resting one leg while at rest or standing

• Resistance to flexing a hind leg, especially for a prolonged time, such as during farrier visits

• Swelling of the hock

Causes of Hock Lameness in Horses

Hock lameness may be caused by a variety of different reasons. The most common causes include:

Osteoarthritis (OA)

Arthritis is by far the most common cause of hock lameness. It usually can appear slowly over time and begins with a subtle level of lameness.

As the bone remodels due to inflammation from constant stressors, the horse experiences pain from lack of normal joint motion and less cartilage acting as a buffer. The horse can learn to move with a shorter stride or less propulsion because it causes less pain.

Osteochondrosis Dissecans (OCD)

OCD in horses is a developmental condition where the cartilage at the end of bones does not form properly. OCD in a younger horse can be caused by rapid growth or feeding too much nutritious food.

If there is a bone chip fragment in the joint, these will usually require surgery to resolve the lameness. OCD lesions can appear as a sudden swelling of a joint with or without lameness.

Trauma

Trauma (horses kicking walls or a kick from another horse) could lead to fracture of one of the bones in the hock.

Infection

Along with bones, there are tendons that course their way around the hock. Infections can occur if bacteria are able to get under the skin from a wound or puncture, which can cause a large amount of heat and swelling around the hock but may not necessarily be in the hock joint.  

How Veterinarians Diagnose Hock Lameness in Horses

Any lameness diagnosis always starts with watching the horse move at different gaits. Your veterinarian will watch the horse walk and trot in a straight line, as well as lunge in a circle at the trot. Depending on the lameness, the horse may be asked to canter during lounging.

Next your veterinarian will examine the feet with hoof testers to make sure the lameness is not caused by the feet.

Flexion tests will then be performed which entail flexing the hind legs one at a time, and then having the horse trot off once the leg is released from flexion. This will make subtle lameness more apparent, as well as help localize the lameness to the joint that was flexed.

If the lameness cannot be localized to the hock by the exam and flexions alone, then your veterinarian may need to block out the lameness. Injections of a numbing agent are used, so that when the area that the pain is coming from is numb, the horse will trot with less lameness than before (but usually not completely sound).

Once it is determined that the area the lameness is coming from is indeed the hock, then X-rays and ultrasound may be used.

Tell your veterinarian if the horse has been showing at higher levels than before, or being ridden more times per week, as well as if any incidents with other horses have occurred that could have led to trauma. Also include if there have been any changes in feeding and type of feed, which can be important in young, growing horses.

Treatment for Hock Lameness in Horses

Treatment for hock lameness depends on the initial cause. Bony changes are not curable and need to be managed. Inflammatory changes that have not yet caused changes in the bone can be more readily managed or even resolved.

Common treatments may include administering NSAIDs (such as bute and Equioxx), as well as joint-specific treatments. These can include injections of steroids, hyaluronic acid, and the newer hydrogels.

Joint supplements can also be given IV or IM (Adequan, Legend). Oral joint supplements can be one of the things owners can implement themselves at home.

A physical therapy plan may also be initiated that may include some rest with a gradual return to work. 

Recovery and Management of Hock Lameness in Horses

Recovery from hock lameness depends on the severity of the lameness and the changes within the joints.

For mild cases that have had joint injections, only a few days of rest are required before the horse can return to a low level of work.

For a horse that has had surgery for an OCD or fracture, then you can expect a longer rest period of several months.

Generally, most horses will have some period of stall rest while also on an NSAID, then resume a gradual return to work. Your veterinarian can help guide you on an appropriate timeline for your horse.

Some horses may benefit from chiropractic or acupuncture, as they may have sore backs from abnormal movements when they were lame. Cold hosing and bandages are mainly useful in cases of hock lameness caused by tendon sheath infection.

Medications that an owner can give their horse to help negate further deterioration of hock and other joints are injectable joint products such as Adequan IM (prescription).

Oral joint supplements can be beneficial as well. Check out these options:

• Lubrisyn HA

• Equithrive Joint

• Cosequin ASU

• Corta-Flx

Prevention of Hock Lameness in Horses

Follow these tips for hock lameness prevention:

• Properly warm up and cool down your horse before and after strenuous performance.

• Keep your horse at an ideal weight and fitness level.

• Foster a good relationship with your farrier in order to keep the hind feet properly trimmed and shod.

• Consider oral joint supplements and injectable joint supplements with guidance from your veterinarian.