Abscesses in Cats: Signs, Treatment, and Prevention

How a bite becomes an abscess

A cat's canine teeth are long and sharp. They leave small, deep puncture wounds that are easy to miss under the fur. The skin over a puncture seals quickly and traps bacteria from the other cat's mouth underneath.

The bacteria multiply in the warm tissue, and the body sends white blood cells to fight them. Pus builds up and forms a swollen pocket. Swelling and pain often appear a few days after the fight, when the bite itself may be hard to find.

Where the skin is loose, as on the neck, shoulders and back, the pus tends to collect in one pocket. Where the skin is tight, as on the legs and tail, the infection is more likely to spread through the tissue. This spreading infection is called cellulitis. It causes a painful, puffy swelling with no clear edges.

Bites are most often found on the head, the front legs and the base of the tail. Abscesses can also form around an infected tooth root, in the anal sacs near the bottom, or in organs inside the body. This guide focuses on abscesses caused by bites.

Signs to watch for

Often the first thing owners notice is that the cat is quiet, hides or eats less. The swelling itself may only be found when you stroke the cat and it flinches. Common signs include:

• A warm, painful swelling. It may feel firm, or soft like a small water balloon.
• A small scab, or a patch of damp or matted fur over the sore area.
• Limping, if the bite is on a leg.
• Licking or grooming one spot much more than usual.
• Fever, tiredness, hiding and poor appetite.
• Thick, bad-smelling fluid leaking from the skin if the abscess has burst.

Some owners only find the abscess after it bursts. The swelling goes down and there is an open wound with wet fur around it. A vet check is still recommended. A burst abscess may drain only partly, leaving small pockets of pus under the skin as the surface heals over.

When it is an emergency

If you know your cat has been in a fight, or you find a swelling, it is best to contact your vet promptly. Call the same day, or go to an emergency clinic out of hours, if you notice any of the following:

• The cat is very weak, will not get up, or has stopped eating.
• The swelling is on the face near an eye, on the chest or on the belly.
• The swelling spreads quickly, or the skin over it turns dark, feels cold or starts to come away.
• The cat is breathing fast or with effort.

How vets diagnose and treat it

A vet can usually recognize a bite abscess by examining the cat and feeling the swelling. Clipping the fur often shows the small puncture marks. If the cause is unclear, the vet may draw a little fluid with a needle to check that it is pus. A sample may also go to a lab to identify the bacteria, a test called a culture. This is more common when an abscess keeps coming back or does not respond to treatment.

Blood tests for feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are often recommended after a fight wound, because both viruses can pass between cats through bites.

Treatment usually starts with opening and draining the abscess. This is painful, so the cat is often sedated or given a general anesthetic. The vet clips the fur, lets the pus out, flushes the pocket with sterile fluid and removes any dead tissue. A large abscess may need a drain, a soft tube that lets fluid escape for a few days while the wound heals.

The vet will decide whether antibiotics are needed and which ones to use. Pain relief is usually part of the plan as well. With treatment, most bite abscesses heal in about five to seven days. Swelling from cellulitis can take longer to settle.

Opening or squeezing the swelling at home is not recommended. It hurts the cat, and a cat in pain may bite.

Care at home during recovery

Your vet will explain how to care for the wound, and may suggest keeping the cat indoors until it has healed. A common routine is to gently wipe away discharge with warm water and clean gauze, often twice a day for the first few days. Hydrogen peroxide can slow healing, so vets usually advise against it. Some household disinfectants, such as those that contain phenols, are toxic to cats.

If a drain was placed, keep the skin around it clean and watch that the cat does not pull it out. A cone collar can stop licking and chewing if the vet recommends one. Give all medicines as prescribed and finish the full course, even if the cat seems better. Wearing disposable gloves while you clean the wound, and washing your hands afterwards, is a sensible habit.

Contact the vet again if the swelling returns, the discharge increases, the wound is not clearly better after a few days, or the cat stops eating or seems more unwell. An abscess that keeps coming back may point to infection that did not fully clear, a foreign object such as a broken tooth or claw in the wound, or a weakened immune system. Your vet can suggest further tests.

Risks to other pets and people

For other cats, the main concern is the viruses that can pass through bites. FIV spreads mainly through deep bite wounds, and casual contact such as sharing bowls does not appear to spread it easily. FeLV can spread through bites and also through saliva, for example during mutual grooming or from shared food bowls and litter boxes. A negative FIV test soon after a fight may come too early to be reliable, so vets often advise a repeat test at least 60 days later.

There is no evidence that FIV infects people. For people, the main risk is a bite from the cat, since a cat in pain may bite when the sore area is touched. Bacteria that live in most cats' mouths, such as Pasteurella, often cause infection in cat bite wounds. Wash any bite or scratch right away with soap and running warm water. It is wise to see a doctor if the wound becomes red, swollen or painful, if the bite is on the hand or face, or if you have a weakened immune system.

How to lower the risk

Most bite abscesses come from fights, so the best prevention is fewer fights. Unneutered males with outdoor access are the most likely to fight and the most at risk of FIV. Neutering reduces fighting. Keeping cats indoors, or giving them a secure garden or enclosure, lowers the risk further.

If your cat goes outside, check it regularly, especially after you hear a fight. Run your hands over the head, legs and tail base and look for tender spots or small scabs. A vet visit at this early stage is usually simpler than treating a large abscess later. Your vet can advise on vaccinations, including rabies where the law requires it, and on FIV and FeLV testing. For first aid on a fresh bite, see our guide to wounds and bite injuries in dogs and cats.

Rescued and newly adopted cats

Cats that lived on the street, and unneutered males in particular, are more likely to have fight wounds. At Paw Squadron, the first stops after every rescue are the vet and a bath. Each animal has a checkup, deworming and treatment against fleas and other parasites. Before adoption, every animal gets a checkup, treatment, vaccinations and a microchip.

After adoption, a fight with a resident cat can cause new bite wounds. It helps to keep a new cat indoors while it settles in and to introduce it to other cats slowly, keeping them apart at first. Your vet can advise on FIV and FeLV testing before the cats share a home.

If you notice a swelling, limping or a sudden change in mood in your cat, contact your vet. For questions about adopting, see our FAQ, or read more cat health guides in PawPedia.