Causes of Canine Abscesses
Most abscesses in domestic dogs are caused by the invasion of healthy tissue by bacteria. Occasionally, abscesses are caused by fungal or protozoal microorganisms or even by parasitic worms, which are called “helminths.” One of the most common ways that dogs develop abscesses is when bacteria are inoculated under their skin through a bite wound, puncture, scratch, cut or other skin surface abrasion. The bacteria multiply inside the wound and start to digest and break down adjoining tissue. The bacterial infection is accompanied by an inflammatory reaction, which involves increased blood flow to the infected area, swelling, redness and pain. The by-product of this localized process, and the product of the digestion of dead and dying tissue, is a thick exudate commonly called “pus.” Pus is made up of white blood cells (leukocytes), a thin fluid called “liquor puris” and cellular debris. Eventually, the inflammatory process stimulates the creation of a fibrous capsule around the wound site, which is then called an “abscess”. If the accumulating pus is not reabsorbed by the dog’s body or otherwise drained out of the abscess cavity, it will put pressure on surrounding structures and can be extremely painful. Eventually, if left unattended, most superficial abscesses will rupture and drain on their own, which can be startling for unsuspecting owners and quite messy.
While abscesses in or just below the skin are the most common type of abscesses in companion dogs, they can also develop internally. Other common sites of canine abscesses are the anal sacs, prostate gland, mammary glands, brain, mouth and gums, tooth roots, pancreas, liver and lungs. Internal abscesses are more difficult to identify and treat than superficial abscesses. However, they too are usually caused by a localized, walled-off bacterial infection.
Prevention of Abscesses
Skin abscesses can be avoided by preventing dog fights, cat bites and exposure to sharp, penetrating foreign objects. Superficial skin wounds should be cleaned and dried thoroughly, as soon as possible after they occur. The hair around the site should be well-trimmed, to make the area uninviting for bacterial overgrowth.
Anal sac abscesses, which are fairly common in dogs, typically occur after the dog’s anal sacs become impacted. They can be prevented by keeping the anal sacs clear and open through regular manual expression. This is probably best performed by a veterinarian; most dogs don’t enjoy having their anal sacs expressed, and most owners don’t enjoy the process, either. It is a messy, smelly, unpleasant event for everyone involved. If a dog has recurrent anal sac impactions and abscesses, its owner may want to consider having the anal sacs removed surgically, through a simple procedure called an “anal sacculectomy.”
Neutering male dogs greatly reduces their risk of developing prostate abscesses, and spaying females reduces the chance of mammary gland infections and abscesses. Abscesses in the mouth are best prevented by keeping dogs from chewing on dirty, sharp objects such as sticks, stones, hangers, branches or nails. Lung abscesses can develop when a dog inhales plant material, especially foxtails or grass awns, which then becomes lodged in lung tissue. Owners of dogs that spend lots of time outdoors should keep an eye on their noses and mouths. If they have repeated bouts of snorting and sneezing, especially during the Spring and Summer months, it probably is worth a quick trip to the veterinarian to see if a foreign object is stuck in their nasal or oral cavity.
Fortunately, most abscesses respond well to drainage, debridement and antibiotic therapy.