A cat abscess typically appears as a swollen, warm lump under the skin that may be firm or soft depending on how far the infection has progressed. In its early stages, you might notice a raised area that feels hot compared to the surrounding skin, often with hair loss or matted fur over the top. If the abscess has ruptured, you’ll see an open wound oozing thick, foul-smelling pus that can range from yellowish-green to brownish in color.
Where Abscesses Usually Appear
The most common cause of abscesses in cats is a bite wound from another cat. Because of this, abscesses tend to show up in predictable spots that correspond to how cats fight. The tail, face, head, neck, and legs are the most commonly affected areas. A cat that was bitten while running away will often develop an abscess near the base of the tail or on the hindquarters. A cat that stood its ground is more likely to have one on the face, head, or front legs.
You might not notice the initial bite at all. Cat teeth leave small puncture wounds that seal over quickly, trapping bacteria beneath the skin. The abscess develops over the next few days as infection builds under that sealed surface.
How an Abscess Changes Over Time
In the first day or two, you may see nothing more than a small scab or puncture mark. As bacteria multiply beneath the skin, the area begins to swell. At this stage the lump often feels firm and warm to the touch. Your cat will likely pull away or hiss if you press on it.
Over the following days, the lump fills with pus and becomes softer. A mature abscess has a fluid-filled quality when you gently press it, almost like a water balloon under the skin. The fur over the swelling may fall out or become matted and damp. The skin itself can look reddish or even take on a purplish tint as the tissue stretches and the infection worsens.
Eventually, if untreated, the abscess ruptures on its own. This is often the moment owners first realize something is wrong. The ruptured site looks like a ragged, open wound with thick discharge that has a distinctly unpleasant smell. The pus is typically yellowish, greenish, or brown, and the surrounding fur will be wet and matted with it. Some owners describe finding a damp, smelly patch on their cat’s fur or on bedding before they see the wound itself.
Behavioral Signs to Watch For
Before an abscess becomes visually obvious, your cat’s behavior often changes. Cats with developing abscesses frequently become lethargic, withdrawn, and lose their appetite. These changes are driven by fever. A cat’s normal body temperature ranges from 100.5 to 102.5°F (38.1 to 39.2°C), and an abscess pushes it higher as the body fights the growing infection. Even after an abscess ruptures and drains, fever can persist.
You might also notice your cat limping if the abscess is on a leg, or avoiding being touched in a specific area. Some cats stop grooming, which can make the matted fur around the abscess site even more noticeable. Dehydration is common because cats with fever tend to eat and drink less.
Dental Abscesses Look Different
Not all cat abscesses come from bite wounds. Tooth root abscesses are another common type, and they look quite different. When a tooth root becomes infected, the swelling typically appears on the face rather than the body. If an upper premolar is involved, the tissue just below the eye swells and becomes inflamed. This is frequently mistaken for an eye infection or a puncture wound because the tooth roots sit so close to the eye socket.
A dental abscess can also cause visible redness and swelling along the gumline inside the mouth. If the infection breaks through, it may drain onto the face (for upper teeth) or beneath the chin (for lower teeth), leaving a crusty, weeping sore on the skin. Inside the mouth, you might notice a bad smell or see your cat drooling more than usual, chewing on one side, or dropping food.
How Abscesses Differ From Lumps and Tumors
A new lump on your cat can be alarming, and it’s natural to wonder whether it’s an abscess or something more serious. A few features help distinguish them. Abscesses develop quickly, usually over just a few days, and are almost always accompanied by heat, pain, and behavioral changes like fever and appetite loss. Tumors and cysts tend to grow slowly over weeks or months and are usually painless in the early stages.
Abscesses also feel different. They’re warm to the touch and become progressively softer as pus accumulates, while tumors tend to feel firm or rubbery and stay the same temperature as surrounding skin. That said, a vet can’t always tell the difference by feel alone. When there’s any doubt, a small needle sample of the lump’s contents confirms whether it’s filled with pus or something else entirely.
What Happens at the Vet
If the abscess hasn’t ruptured yet, the vet will typically lance it, meaning they make a small incision to drain the pus. The wound is flushed to clear out as much infected material as possible, and your cat will go home with antibiotics. In some cases the vet leaves the wound partially open or places a small drain to prevent it from sealing over and refilling.
The bacteria most commonly responsible for cat bite abscesses, Pasteurella multocida, is a normal resident of cat mouths. It’s introduced deep into tissue through the puncture wound and thrives in the low-oxygen environment under sealed skin. This is why antibiotics are a standard part of treatment: the infection needs to be cleared from inside, not just drained.
Most abscesses heal within about a week after drainage. Larger or deeper infections can take longer. If the wound hasn’t closed and the swelling hasn’t resolved after a week, that’s worth a follow-up visit. During recovery, you’ll likely need to keep the area clean, prevent your cat from licking the wound excessively, and finish the full course of antibiotics.
Why Outdoor Cats Are Most at Risk
Cats that go outside and encounter other cats are far more likely to develop bite wound abscesses. Unneutered males are at the highest risk because they’re the most territorial and most likely to fight. Neutering significantly reduces fighting behavior and, with it, abscess risk. Keeping cats indoors eliminates the most common source of these infections entirely.
If your cat does go outside, checking them regularly for small scabs, puncture marks, or areas of tenderness can help you catch an abscess in its earliest stages, before it becomes the swollen, painful mass that most owners eventually find.