Dog Pressure Sores (Calluses; Hygromas)

Introduction

Pressure sores are areas of skin and underlying tissue that are located over bony prominences and have been damaged by trauma from prolonged pressure or friction. They include calluses, which are thickened, hairless, wrinkled areas of skin over a bony pressure point. They also include hygromas, which are soft, usually painless, fluid-filled subcutaneous sacs (bursas) localized over bony areas where friction occurs – especially over the elbows. Another name for pressure sores in dogs is decubital ulcers. Calluses are quite common in companion dogs. Hygromas are seen less frequently, although they are not considered to be rare.

Causes & Prevention

Causes of Pressure Sores
Pressure sores are almost always caused by chronic trauma to a dog's skin and subcutaneous tissue as a result of lying on hard surfaces for prolonged periods of time. Pressure sores are common in domestic dogs, especially in large, heavy or giant-breed dogs and those that are kenneled on cement floors without soft, well-padded bedding. Long-term pressure on an area of the body where the bone and skin are thinly separated compresses the blood vessels and decreases the blood supply to the area, which in turn causes tissue damage and, ultimately, tissue death (necrosis), calluses and hygromas. The elbow is probably the most common site of pressure sores, although they also frequently occur on the hips, hocks and sides of the legs.

Prevention of Pressure Sores
The best way to prevent pressure sores is to provide dogs with lofty, well-padded bedding in all areas where they regularly rest. Dogs that are recumbent for medical reasons are especially at risk of developing pressure sores. They should be given very soft, thick, well-padded beds to lie on; egg crate foam, thick foam rubber, waterbeds or inflatable airbeds are all good options. Recumbent dogs should be physically turned (have their position changed) every 2 to 3 hours, to prevent concentrated pressure on their elbows, hocks, hips and other thin-skinned bony areas. Massage, hydrotherapy and other forms of physical therapy can be helpful by stimulating blood circulation to affected sites.

Special Notes
Pressure sores are common in companion dogs. The highest incidence is seen in large and giant breeds and dogs who are crated or otherwise forced to lie down for extended periods of time.

Symptoms & Signs

Introduction
Dogs with pressure sores – which include both calluses and hygromas – usually have a history of being housed on hard surfaces (cement, brick, wood), without well-padded bedding. They also commonly have a history of being recumbent (lying down) for prolonged periods of time.

Symptoms of Pressure Sores
Pressure sores are visibly obvious. The most common site is on the elbows, but they also can occur on the hips, hocks, chest (sternum), side of the legs or anywhere else on the body. Owners of dogs with pressure sores may not notice the condition until the sores actually break open and ulcerate, or until their dogs are chronically licking at the affected site. Owners may notice one or more of the following signs of pressure sores in their dogs:

Hairless, wrinkled, hyperpigmented (red-to-purple) pad of thickened skin over a bony pressure point
Fluid-filled area over a bony prominence
Ulcer, abscess or weeping wound over a bony prominence
Lameness
Licking at the affected area (often accompanied by stained hair coat at the site of the sore)
Dogs at Increased Risk
Any dog, of any breed or mixed breed and of either gender, can develop pressure sores. However, they are most common in large and giant-breed dogs - such as the Mastiff, Cane Corso, Irish Wolfhound, Great Dane, Labrador Retriever and other large breeds - because their weight and size are disproportionately concentrated on bony pressure points, especially their elbows and hocks, when they are lying down. Dogs with weakened immune systems are more likely to develop infections at the sites of pressure sores. Dogs that lie down (are recumbent) for prolonged periods of time – especially if they are housed on hard surfaces without soft bedding – have an increased risk of developing pressure sores. Malnourished and emaciated dogs also are predisposed to developing pressure sores, because they lack the normal tissue "padding" around their elbows, hocks and other bony areas.
How Pressure Sores are Diagnosed
Pressure sores are not difficult to diagnose. They are not a "disease" or a "medical disorder," but rather are a physical skin and subcutaneous tissue condition caused by pressure, friction and trauma. They are, basically, a "sore."

A thorough history and physical examination are the most important tools in diagnosing pressure sores. The diagnosis is usually made based upon clinical observations and upon the owner's explanation of the environment and surfaces upon which the dog lies. If the pressure sore is ulcerated or infected, the attending veterinarian probably will take samples of the oozing exudate with a sterile cotton swab, and then will submit the samples to a diagnostic laboratory for microscopic examination and culture. Skin biopsies may also be taken for diagnostic examination, depending upon the location and appearance of lesions in the particular patient. Biopsies are important to distinguish pressure sores from potential cancerous masses. In the uncommon case where involvement of bone is suspected, radiographs (X-rays) of the affected area may be recommended.

Special Notes
Pressure sores can be very frustrating to owners of affected dogs. The best way to deal with them is to provide well-padded bedding everywhere that the dog tends to rest, to relieve pressure on its elbows, hocks, hips or other bony pressure points.

Treatment Options

Treatment Options
It is imperative that dogs with pressure sores be provided with well-padded, thick, soft sleeping surfaces at all times, to prevent further trauma. This may be all that is needed to decrease the size of the pressure sores and prevent their progression. There are many commercially available dog beds, mattresses and fabric-covered foam pads that will take the pressure off of bony prominences when a dog is resting or sleeping. If a pressure sore is not infected, adding soft bedding to the dog's living environment - and observing the dog when it is lying down or resting - are probably all that is necessary to manage the condition. The site of the pressure sore should be wrapped with a padded bandage to prevent further trauma to the area as it heals. Moisturizers, aloe lotions or antibiotic ointments or gels can be applied to the affected area to soften the rough skin and provide some relief from discomfort. The area should be bandaged after these substances are applied, to reduce the risk of secondary bacterial infections developing in the moist environment.

If pressure sores become infected, the veterinarian will need to inspect the site more carefully. He probably will take a sample of the oozing exudates on a cotton swab and submit it to a diagnostic laboratory for culture and sensitivity, to identify the precise microorganisms that are responsible for the infection. Long-term antibiotic treatment, both orally and topically, is usually recommended to treat infected pressure sores. A typical course of oral antibiotic treatment is 4 to 6 weeks, at a minimum.

Dogs with hygromas – fluid-filled sacs over areas of pressure, also called bursas – may be treated by draining and flushing the lesion. If caught early, this can be accomplished by needle aspiration, which basically involves inserting a needle into the hygroma and extracting its fluid contents into an attached syringe by pulling on the plunger. The fluid inside hygromas usually is clear or yellowish-to-red. The aspiration site should be well-padded and bandaged after this procedure. However, unless the underlying cause of the hygroma is resolved, most of them will return after being drained by a veterinarian.

Surgical excision (removal) of calluses or hygromas is usually not recommended. Laser therapy may be helpful for small pressure sores, although this treatment is not yet widely available. Pressure sores with extensive ulceration may require surgical skin grafts. Some authorities report that slathering the sores with raw honey or wound-healing creams may accelerate healing.

All pressure sores should be cleaned daily with an antiseptic solution, which the attending veterinarian can recommend. This often is a chlorhexidine solution.

Prognosis
Unfortunately, because of their location on areas where bone and skin are in close proximity and where constant friction is present, pressure sores can be difficult to treat. Most calluses can be controlled by consistently providing appropriate lofty bedding, although it can take a long time for calluses to go away once they have developed, despite well-padded bedding. Fluid-filled hygromas often require more invasive techniques, such as surgical drains, to resolve them.