Skin infections in Cats
Skin disease in cats can be caused by a number of conditions, ranging from trauma and bite wounds to parasites (including fleas, ringworm and mange) or bacterial infections secondary to underlying allergies (flea bites, inhalant/contact allergens, food allergies).
A cat’s lifestyle, gender, and breed can affect their risk of various skin conditions. Cats allowed outdoors have a greater chance of infestation by external parasites such as fleas, and a higher risk of injury and abscesses from fighting with other cats or animals. In addition, male cats, particularly those who are not neutered are more likely than female cats to engage in aggressive behaviour that may result in bite wound-induced abscesses. In the UK abscesses are the most common cause of skin disease in feline patients.
Common signs of skin disease in cats include excessive scratching, licking, or chewing of the fur, redness and swelling of the skin, bald patches from loss of fur, scabby, scaly, or flaky skin, and swellings or bumps on the skin.
The skin is the largest organ in a cat’s body, comprising up to ¼ of its body weight. It provides an important barrier to the environment protecting against the hostile external environment. Helping to prevent access to a host of would-be invaders, such as bacteria, fungi, yeasts, mites, insects and viruses.
Yeast infection (Malassezia) seen under the microscope
Bacterial skin infection (pyoderma)
The most common bacterial skin infections in cats are secondary to trauma, most commonly from a cat bite abscess. Cats have nasty bacteria in their mouths and when they bite they inject these bacteria deep into the skin with their teeth. This initial wound becomes inflamed and over several days the bacteria multiply forming an often large pus filled swelling under the skin.
Cats can develop an allergic reaction to many things, including fleas, allergens they inhale (which include mould, pollen and house dust), contact dermatitis, which is caused by irritating substances coming in contact with your cat’s skin (which can include soaps, household or garden sprays, chemicals, feathers and even some flea collars) or certain types of food. Allergies are typically very itchy (pruritic) and cats can develop secondary skin infections to these underlying allergies.
Flea allergic dermatitis (FAD) is the most common allergic skin disease seen in cats. This occurs when cats develop an allergy to the flea saliva. Just one flea bite can cause intense pruritus in these cats, sometimes leading to hair loss and small scabs on their skin (known as miliary dermatitis).
It is important to know what bacteria are involved in a skin infection to guide making the best choice of antimicrobial therapy. To do this, your vet may take samples for microscopic examination and possibly culture and sensitivity to find the type of bacteria involved in the infection.
Cytology picture showing bacteria from a cat’s skin
Treatment of a cat bite abscess: Draining and cleaning the abscess, pain relief and antibiotics to treat the infection if needed. Treatment of a secondary bacterial infection (for example to an underlying allergy): Antibiotics and medication may also be prescribed to reduce the inflammation and pruritus (itch). Support of damaged skin/hair. Various shampoos and diets can help to promote a healthy skin and coat.
Treatments for skin parasites will also be necessary if parasites have been identified and ensuring effective flea control is up to date, to avoid flea bites flaring up the skin, this is particularly important in cats with FAD.
Your veterinary surgeon will select the treatment/s appropriate to each individual case. Long-standing cases will need treatment for many weeks. Many weeks of antibiotic treatment may be necessary for long-standing or deep infections. It is very important that antibiotics are given exactly at the frequency and interval prescribed and that no doses are missed. A common reason for treatment failure is the owner missing doses or not completing the full course of antibiotics. The course should be completed even if your cat’s skin already looks a lot better. Alternative longer acting treatments are available and your veterinary surgeon will decide upon the best treatment regime. It is important not to cut short any period of treatment that your veterinary surgeon prescribes.
Photos with kind permission from Anita Patel.