True bacterial pyoderma is not common in cats in the way it is in dogs. Skin diseases as a whole are common, but bacteria are often not the primary cause.
When to see a vet urgently
Ask for an urgent assessment if skin changes are accompanied by any of the following:
- Your cat is clearly listless and not eating.
- A very painful swelling has developed rapidly under the skin.
- A wound drains large amounts of pus or the surrounding area becomes swollen and tender.
These can indicate an infection deeper than superficial skin inflammation. You can find a vet near you.
Overview
The skin acts as a natural barrier against microbes. When this barrier is broken, for example by scratching, injury or inflammation, bacteria can enter its surface layers and cause infection. The most common causes are staphylococci and streptococci. Disease may be confined to a small area, such as around the ears or tail, or spread more widely.
Bacterial skin infection is also called pyoderma. Superficial infection is confined to the outer skin layers and upper hair follicle, whereas deep infection extends further into the skin. Depth affects both symptoms and treatment selection. Staphylococci are often isolated from superficial infections in cats, but the cause cannot be inferred from the skin's appearance alone.
An abscess following a bite wound is a separate form of bacterial infection. A small tooth puncture can carry bacteria from the mouth deep into tissue, where a pus-filled cavity develops. This differs from superficial infection in allergic skin. A cat can have several skin diseases at once, so identifying one finding does not always explain every symptom.
Causes
The main causes underlying bacterial dermatitis include:
- allergies, including atopy and flea allergy dermatitis,
- parasitic diseases involving fleas or mites,
- skin injuries, including bites and scratches,
- fungal diseases that weaken the skin,
- reduced immune defences because of chronic diseases or stress,
- poor hygiene and a damp environment.
Not every factor listed has been established as an independent cause of feline skin inflammation. Stress or household humidity alone, for example, is not enough to explain it. Allergies, parasites and skin damage are important underlying factors to investigate in practice. With a poorly healing or recurrent deep infection, systemic diseases such as viral infections affecting immunity may also be investigated.
Risk factors
- kittens and elderly cats with weaker immune defences,
- cats with chronic skin diseases,
- animals living in unhygienic conditions,
- cats with recurrent allergic reactions.
Information about precisely defined risk factors in cats is limited, so age or cleanliness alone does not establish disease. An infection can develop at any age if the skin is damaged. Free outdoor access also increases the possibility of fight injuries and associated abscesses. Risk assessment considers the cat's skin diseases and lifestyle.
Symptoms
Typical symptoms include:
- itching and constant licking or scratching,
- red, inflamed skin,
- pustules and small bumps,
- scabs and crusts,
- hair loss from inflamed areas,
- an unpleasant skin odour in severe cases.
Intact pustules are rarely seen in cats. You may feel small, hard scabs in the coat or notice increased scaling before obvious hair loss. However, this bumpy skin reaction alone does not identify the cause: allergies and parasites can look similar.
Deep infection may involve ulcers, bloody crusts and openings draining pus. A cat with an abscess may avoid being touched and become generally unwell. Tell the vet when the changes began, how they spread, about outdoor access and possible fights, and which medicines have been used. Photographs from different stages can help compare changes, but do not replace examination of the skin.
Possible complications
Untreated bacterial dermatitis can cause:
- a chronic, recurrent course of disease,
- spread of infection over large skin areas,
- secondary fungal infections,
- general debilitation because of ongoing inflammation and itching.
Yeast and bacterial infections can occur together. Finding yeast does not always mean the bacterial infection caused it: the same underlying skin disease can predispose to both. Deep infection is more serious than superficial infection and requires a more detailed treatment assessment. With prolonged itching, its original cause must also be investigated so that scratching does not damage the skin again.
Diagnosis at the vet
Diagnosis uses:
- a clinical examination and history,
- skin sample smears and cytology,
- bacterial culture to identify the pathogen,
- allergy tests and parasite investigations to explore the underlying cause.
Allergy tests alone do not diagnose environmental allergy or bacterial infection in cats. Environmental allergy is assessed from the pattern of symptoms and exclusion of other causes. Blood or skin allergy tests may later help plan individual allergy treatment.
What do samples look for?
Cytology means examining cells and microbes under a microscope. A sample can be collected from a skin lesion with tape, a microscope slide or a swab. The vet assesses bacteria, inflammatory cells and any yeasts. Culture grows bacteria from the sample, and susceptibility testing helps choose a medicine effective against them. Culture is particularly important in deep, recurrent or poorly responding infection.
Skin scrapings can look for parasites. Ringworm, a fungal skin disease, needs tests suited to investigating it. An unusual or poorly healing lesion may be biopsied: not every pus-producing or crusted skin change is an ordinary bacterial infection. The extent of testing depends on the findings.
Investigating an underlying allergy
The vet asks whether itching is constant or seasonal and whether your cat has had previous skin or ear infections. Similar skin symptoms can result from parasites, food allergy or environmental allergy. Bacterial culture cannot distinguish these. Overall health is also assessed, with blood and urine testing when needed.
Food allergy can develop even if a cat has eaten the same food for a long time. Investigation uses a vet-supervised diet trial. During the trial, the cat receives only the agreed diet and water so other foods do not interfere with interpretation. Improvement and any recurrence after reintroducing the previous food are assessed systematically. Simply changing food occasionally does not confirm an allergy.
Treatment and monitoring recovery
Topical treatment or systemic medication?
A superficial infection may be treated with a topical antiseptic selected by the vet. This might be a shampoo, wipe or gel. The choice depends on how widespread the changes are, the coat and whether application is practical. The product must suit cats and the particular skin area. The vet separately assesses when an oral or injectable antibiotic is needed; deep infection in particular may require one.
Itching in an allergic cat often needs its own treatment too. Controlling bacterial infection does not remove flea allergy or another underlying disease. Recurrence may result from a continuing predisposing condition, difficulties carrying out treatment or a bacterium resistant to the medicine. This requires reassessment, rather than simply restarting the same antibiotic on your own.
An abscess may need opening, draining and flushing at the practice. This can be performed under sedation or general anaesthesia. Sometimes the wound is left open or a drain, a tube allowing fluid to escape, is inserted. A small-looking opening does not reveal the extent of inflammation beneath the skin.
Home care
Prevent constant licking of the affected area as advised by the vet. A protective collar or other protection may be needed if your cat damages the skin. Do not apply human creams, alcohol, hydrogen peroxide or essential oils to the wound. They can irritate tissue, delay healing or harm your cat when licked. Agree the cleaning product and technique with the treating vet.
Give prescribed medication as instructed. If administration is not possible or handling is painful, report this so the approach can be adjusted. Monitor the quantity and nature of discharge, redness, swelling, licking and appetite. Increasing pus or deteriorating general health requires contact with the practice. Follow-up checks skin healing and repeats samples when needed before treatment decisions are changed.
Prevention
- regular flea and tick protection,
- keeping the home and the cat's resting areas clean,
- early recognition and treatment of allergies,
- preventing skin injuries and scratching,
- regular veterinary checks.
Flea control considers both the cat and the environment: treating the animal alone does not resolve an ongoing household flea problem. Vacuuming and cleaning resting areas support control. Use only cat-suitable products under veterinary guidance. To prevent scratching wounds, the cause of itching must also be controlled; washing the skin alone does not replace treatment of an allergy or parasitic infection.
This text provides general information and does not replace veterinary care. If your cat develops symptoms, contact a vet.
Frequently asked questions
Are bacterial skin infections common in cats?
Ordinary bacterial pyoderma is less common in cats than in dogs. However, abscesses caused by bite injuries are common. Distinguishing these helps explain why a localised pocket of pus and a widespread crusted rash may need different investigations and treatment.
Does a cat's skin infection always need antibiotics?
Not always. Topical treatment may be enough for a superficial infection, while a deep infection may need a systemic antibiotic. Draining an abscess can be a central part of treatment. The approach depends on infection depth, sample results and the cat's condition.
Why is the skin still itchy after treatment for bacterial infection?
An allergy or parasitic disease sustaining the itch may continue after bacterial numbers fall. Alternatively, the infection may not yet have healed. A follow-up examination helps distinguish these situations. A new antibiotic or anti-itch medicine is not selected solely because your cat is still licking its skin.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
- Pyoderma in Dogs and Cats, Merck Veterinary Manual, accessed 2026-11-03.
- Pyoderma in Cats, Merck Veterinary Manual, accessed 2026-11-03.
- 1.2 Feline Pyodermas, University of Minnesota Libraries, accessed 2026-11-03.
- Feline Skin Diseases, Cornell University College of Veterinary Medicine, accessed 2026-11-03.
- Atopic Dermatitis (Atopy) in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Food Allergies, Cornell University College of Veterinary Medicine, accessed 2026-11-03.
- Care of Open Wounds in Cats, VCA Animal Hospitals, accessed 2026-11-03.
- Fleas, Cornell University College of Veterinary Medicine, accessed 2026-11-03.