Hygromas are soft, benign, fluid-filled masses that form over bony prominences in young adult large- and giant-breed dogs in response to repetitive pressure or blunt trauma.1-3 Hygromas are typically located over the elbows, although they have been reported in other regions (eg, tuber calcaneous, tuber ischium, carpus; Figures 1 and 2).1 As the bony prominence hits the floor or other hard surfaces, subcutaneous tissue over the bone is damaged. Repetitive trauma results in formation of a pocket of serous fluid that is surrounded by a fibrous capsule and, in some cases, contains granulation tissue.1-3
Most hygromas are nonpainful, but they can enlarge, ulcerate, and become infected (Figures 2 and 3).1-4 Prevention of hygroma formation and treatment for small, nonpainful hygromas involves elimination of blunt trauma to bony prominences by providing appropriate bedding or applying regional padding or coaptation devices (eg, casts, splints, bandages).1,4,5 Large, ulcerated, or infected hygromas may require culture, drainage, open wound management, or surgical resection and reconstruction.1-3,6 Even after aggressive treatment, pressure-relieving measures must be continued to allow the site to heal and to prevent future recurrences.3
When selecting or manufacturing a coaptation device, fit is the most important consideration. An ill-fitted coaptation device can result in discomfort, swelling, dermatitis, local tissue necrosis, ulcerations, and muscle atrophy from immobility. In addition, if appropriate positioning is not maintained, the device may not protect the area adequately from further trauma. The device should be lightweight and inexpensive, distribute pressure away from bony prominences, allow unimpeded motion and mobility, and permit appropriate blood flow to the region.4,7 Doughnut-style padding can be helpful for prevention of hygroma formation or enlargement (Figure 4). However, in dogs with ulcerations (Figure 5) or surgical reconstructions, doughnut-style padding redistributes pressure circumferentially to all surrounding tissues, inhibiting blood flow and healing.4 Application of padding distal to the hygroma (Figure 6) can prevent contact of the region with hard surfaces while allowing joint movement and maintaining blood flow along the proximal half of the area. A homemade system from readily available products is especially useful when owner travel is restricted.
Counseling, monitoring, and additional recommendations on care should be based on appearance of the affected area.