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 can form over any bony prominence on the dog’s body, such as the side of the hock (ankle) joint or over the side of the hip, but they are most commonly found over the elbow. When they first form, hygromas 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 caused it?
Hygromas are not tumors. They occur in response to repeated trauma to the tissue over a bony prominence. That is one reason 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 under the skin 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 over the hygroma site. That said, any large or giant breed dog of any age is potentially 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 prevent further trauma by providing bedding with adequate padding. 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 alone may be all that is required for stabilizing the hygroma.
There are now commercially available elbow pads designed specifically to protect hygromas (dogleggs™), in order to 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 will easily tolerate protective elbow pads.
Should the hygroma grow to an unwieldy size or become infected, it will need to be treated with appropriate antibiotic therapy and may need to be removed surgically. Surgery does not address the underlying cause of the hygroma, so protecting the involved area post-op will be critical for good healing. Your veterinarian will help you to decide how best to proceed with your dog’s hygroma.
Can hygromas be prevented?
There are several things to consider for preventing hygromas. The most important is to ensure that a large or giant breed dog is not allowed to become overweight or obese. Extra weight greatly increases the risk for trauma to the tissue over bony prominences. In addition, it is important to provide bedding with adequate padding. Finally, it is worth covering 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.