Hygroma in Dogs

What is a hygroma?

A hygroma is a fluid-filled swelling surrounded by a thick capsule of fibrous tissue that develops under the skin. Hygromas are typically not painful. They are most commonly found over the elbow, but can form over any bone that sticks out on the dog’s body (a bony prominence), such as the side of the hock (ankle) joint or over the side of the hip. 

When hygromas first form, they are usually small, soft, and fairly mobile. They may never grow large enough to even notice. If they do grow larger, they can become unsightly or hard to the touch. In the worst-case scenario, hygromas can become infected, in which case they are painful and must be dealt with aggressively. 

Is a hygroma a tumor? What causes them? 

Hygromas are not tumors. They occur in response to repeated trauma to the tissue over a bony prominence, which is why the elbow is the most common site for hygromas to develop. Especially for large and giant breed dogs, the repeated trauma of lying down on hard surfaces — hardwood, tile, or concrete floors — can produce an inflammatory response in the tissue over the elbow. The body tries to protect the inflamed area by creating the equivalent of a “pillow”. If the trauma continues, the hygroma will grow larger. 

Hygromas tend to be more common in dogs that are sedentary and spend more of their time lying down, thus increasing the time that pressure is applied on the hygroma site. Older dogs with arthritis commonly develop hygromas, but any large- or giant-breed dog, of any age, is at risk of developing a hygroma if they spend time resting and sleeping on hard surfaces. 

How are hygromas treated? 

The first step in treating a hygroma is to provide bedding with adequate padding to prevent further trauma. Egg-shell foam or memory foam beds may provide the best padding. In areas where the dog enjoys relaxing, the floor can be covered with interlocking foam tiles like the ones found in fitness clubs and day cares. Padded surfaces may be the only thing required to stabilize the hygroma. 

There are commercially available elbow pads (DogLeggs™) specifically designed to protect hygromas and prevent them from growing or becoming infected and painful. These elbow pads are sized to the dog and then adjustable for a fine-tuned fit. Most dogs easily tolerate protective elbow pads. 

If the hygroma grows to an unwieldy size or becomes infected, it must be treated with antibiotic therapy and may need to be surgically removed. Surgery does not address the underlying cause of the hygroma, so protecting the involved area is critical for good healing after the operation. Your veterinarian will help you to decide how best to proceed with your dog’s hygroma. 

Can hygromas be prevented? 

To prevent hygromas, it is important that large- or giant-breed dogs are not allowed to become overweight or obese. Extra weight greatly increases the risk of trauma to the tissue over bony prominences. In addition, it is important to provide bedding with adequate padding. Finally, it is worthwhile to cover hard floor surfaces in areas where the dog likes to relax. Once a dog has developed a hygroma, attention to a few details can prevent this condition from becoming a problem.