When your pup lies around, the bones touching the surface of where he's lounging experience slight pressure. Over time, if a dog's making repeated contact in one spot, he'll likely develop a protective callus. Occasionally, a lesion, or pressure sore can develop. Eventually, this can turn into a cystic hygroma.
Becoming a Hygroma
Think about the last time you knelt on a hard surface for some time; you may have developed some sensitive spots or even bruising from putting pressure on the bony surface. If Dexter spends a fair amount of time lying about on hard floors or ground, parts of his body that aren't so well-padded, such as his elbow or femur, may show the effects. If Dexter developed a lesion instead of a callus, left untreated, it begins to break down the affected tissues. As he continues to make contact with the hard surface, fluid develops in a sac in the area of his lesion, developing into a hygroma, or false bursa.
Hygroma: Not a Cyst
Loose tissue separates the hygroma from Dexter's skin in a well-defined sac. The sac has a dense wall and contains fluid, ranging in color from yellow to red. The hygroma resembles a cyst, but it's not a true cyst. A dog cyst can be one of several types of benign skin growths on the surface of the skin. Like the hygroma, it's well-defined in a sac beneath the skin, however, it can contain air, fluid or soft material and is based on the malformation of a hair follicle.
Dexter's hygroma isn't helping his looks, but take heart that it's not painful for him. In most cases, providing him soft bedding and bandages will clear up the hygroma in two to three weeks. If the hygroma is early and still small, the vet may aspirate it to remove fluid. Since hygromas are benign, it's tempting to minimize their potential effect. However, ignoring a hygroma can cause problems for Dexter, requiring more intense veterinary care.
An uncomplicated hygroma can progress to a complicated hygroma. If the hygroma becomes chronic, it may require surgical drainage and flushing. Infection is possible too, requiring surgery, flushing and rubber drains to allow the hygroma to drain. If the hygroma has progressed to the point that it chronically drains or has a large sore, it will need more extensive surgery. Occasionally skin flaps or grafts are necessary to rebuild the skin in the affected area and sometimes splints are used to immobilize and pad a leg that needs to heal.
If Dexter's a big guy with short hair, he may be more prone to developing a hygroma -- his weight and the probability his skin's making direct contact with hard surfaces increase the risk of trauma to vulnerable spots. It's easy to prevent hygromas: Simply make sure he has soft bedding. If he's outdoors a lot, straw may give him a soft spot to lie on. Check his legs for calluses and if you see sores or cysts developing, have the vet take a look to make sure all is well.