A hygroma is a fluid-filled sac that develops over bony prominences and pressure points, especially in large breeds of dogs. Repeated trauma from lying on hard surfaces leads to inflammation. This results in a dense-walled, fluid-filled cavity. A soft, flexible, fluid-filled, painless swelling develops over pressure points, especially the elbow. If long lasting, severe inflammation may develop, with ulcers, infection, abscesses, granulomas (masses of inflamed tissue with sand-like deposits), and tissue erosion. The sac contains a clear fluid, yellow to red in color. If diagnosed early while they are still small, hygromas can be drained and then bandaged. Soft bedding and padding over pressure points is important to prevent further trauma. In cases of chronic hygromas, surgical drainage and flushing are critical for relief. Areas with severe skin ulcers may require extensive drainage, surgical removal, or skin grafting.