Though they are often caused by the same thing – repeated trauma to a bony area – calluses and hygromas are not the same. Hygromas are fluid-filled, where as calluses are not. Calluses are hairless areas of thickened skin over a bony area. Like hygromas, they can become infected.
WHAT IS A HYGROMA?
A hygroma is nonpainful, fluid-filled swelling surrounded by a thick, fibrous capsule that develops under the skin. We usually see hygromas on the outside of the elbow, but we have also diagnosed them on the hip and hock. Hygromas are initially small, soft, and fluctuant and do not pose a problem for the dog. They may be present for the dog’s lifetime. In some instances, though, they may become quite large, up to 2 inches in diameter, or very hard. Hygromas can become infected, in which case they are painful, sometimes warm to the touch, and may develop draining tracts.
WHAT CAUSES A HYGROMA?
A hygroma is caused by repeated trauma to an area over a bony prominence. The trauma most often occurs as a result of lying on hard surfaces, such as cement or hardwood floors. It is more common in larger breed dogs in which more weight is placed on the bony area having contact with the hard surface. Hygromas are also more common in dogs that are sedentary, such as those recovering from surgery or having other medical conditions that make them less active (e.g. hip dysplasia).
HOW IS A HYGROMA TREATED?
The first step in treatment is to prevent further trauma. This is primarily accomplished by providing a soft padded bed. We may also use a donutshaped padding over the elbow, placing the ‘hole’ of the donut over the hygroma. This will protect the hygroma from further contact with anything hard. Simply bandaging the area is often not effective since there would still be pressure on the hygroma if the dog lies on that side.
Periodically aspirating (removing the fluid via needle and syringe) the hygroma is usually not effective and may introduce infection. Likewise, surgery is seldom performed unless the hygroma is infected. Some success has been seen by surgically inserting a drain (latex tubing) into the hygroma to allow for constant drainage. Then the area is bandaged, and the dressings are changed regularly.
HOW IS A CALLUS TREATED?
As with a hygroma, we first want to prevent further trauma through the use soft, padded beds, and bandages, if necessary. If infected, calluses may need to be treated with antibiotics.
HOW CAN A HYGROMA OR CALLUS BE PREVENTED?
Hygromas and calluses can be prevented by providing soft bedding, especially beds made of orthopedic foam. Animals recovering from surgery should be turned from side to side multiple times during the day.