Abscesses form as part of the body's response to infection. Essentially, they are pockets of pus that grow around wounds or areas of infected tissue. Some abscesses may go unnoticed by a cat owner until they rupture and leak fluid. Knowing what to watch for and how to treat abscesses may save your cat's life. Untreated, abscesses can progress into life-threatening systemic infections.
What Is an Abscess?
An abscess is an infected pocket of pus (thick fluid full of bacteria and bacteria-fighting white blood cells). Abscesses are the body's response to tissue infections. Abscesses can be found throughout the body (externally and internally) and are generally smaller than an inch in diameter.
Symptoms of Abscesses in Cats
Abscesses usually appear as a swelling under the skin, particularly in areas that are easily injured in a fight with another cat (head, ears, paws, legs, tail), but they can also occur in the mouth or inside the body cavity.
Abscesses look a lot like a tumor, but they appear more suddenly (often within days of a fight) and are tender to the touch. An abscess is full of fluid, so it will compress if touched and feel somewhat soft or squishy. Abscesses often swell to the point that they start oozing pus and/or blood from the entrance wound (a tooth or claw puncture, for instance). The fluid is foul-smelling and indicative of infection.
If an abscess forms inside the mouth due to a tooth or gum infection, a cat may have notably bad breath, refuse to eat, and become lethargic. Abscesses inside the body may also cause lethargy and a decrease in appetite. Systemic infections caused by untreated abscesses can cause a cat to feel sick and develop a fever.
Causes of Abscesses
The most common types of abscesses in cats are in the mouth and under the skin, but abscesses can occur anywhere bacteria infiltrates tissue. Common bacterial culprits include E. coli, certain Streptococcus species, Pseudomonas, Mycoplasma, Pasteurella multocida, Corynebacterium, Actinomyces, Nocardia, Bartonella, Bacteroides, Clostridium, and Fusobacterium.
These bacteria are often introduced through wounds, injuries, or cavities that occur in various areas of the body, including:
- Dental abscesses: These abscesses are found around diseased teeth. When bacteria accumulate on the surface of a tooth, the gums become inflamed and infected and abscesses can form under the gum line. If bacteria migrate into the root canal of a broken or diseased tooth, an abscess can form in this deeper tissue. Dental abscesses are common in cats but are difficult to notice until definitive signs appear like horrible breath, food refusal, or bloody saliva.
- Bite wound abscesses: In order for a cat to develop a bite wound abscess, it needs to be bitten by another animal. This is why bite wound abscesses are most common in cats that spend time outdoors. When a cat gets bit, bacteria enter the wound and an abscess begins to form. These are seen under the skin of cats as lumps and usually aren't noticed by the cat owner until they rupture and begin to ooze pus. These abscesses may feel hot to the touch as well as cause skin inflammation.
- Internal abscesses: Invisible from the outside of a cat's body, internal abscesses occur on internal organs from inflammation, disease, and foreign objects. These are far less common than bite wounds and dental abscesses.
Diagnosing Abscesses in Cats
If your veterinarian suspects a skin abscess from a bite wound or other injury, and the abscess has not ruptured, then a fine needle aspiration (FNA) may be performed to see what is inside. If it is an abscess, your vet will be able to draw pus into the syringe (this differentiates an abscess from a tumor).
If a dental abscess is suspected, a veterinarian will examine a cat's mouth for evidence of pus but anesthesia and X-rays will need to be performed to thoroughly inspect the mouth. Abscesses will show up on X-rays and dental probes will be used to examine the teeth.
If an internal abscess is suspected, ultrasound may aid a veterinarian in diagnosing it, but surgery is typically needed to find and assess internal abscesses.
Sometimes bacterial cultures will be performed to diagnose the specific type of bacteria causing an abscess. This will aid the veterinarian in determining the appropriate antibiotic treatment.
Antibiotics are the primary treatment for abscesses. A full course of antibiotics may continue for two to four weeks. Tooth extractions may be necessary for tooth root abscesses (along with thorough dental cleaning). Surgery may be necessary to lance skin abscesses to allow the infection to drain or to remove the abscess if it is internal.
Prognosis for Cats with Abscesses
With prompt, aggressive treatment, abscesses are usually easy to treat and will heal quickly. Infections that have spread to the joints, bone, or bloodstream have a higher risk of long-term damage or fatality, but these cases are rare in well-tended cats.
How to Prevent Abscesses
Keeping cats indoors will help prevent abscesses from fighting wounds. Regular dental care and a nutritious diet will help prevent dental abscesses from forming. Some cats have more problems than others with dental disease, but keeping their teeth clean can help prevent abscesses.