Welcome to our hub for skin problems in dogs and cats. This page helps you understand why your dog or cat has a skin problem. It also contains links to many other skin pages. Two other related pages are:
See also specific pages for:
Why Dogs & Cats Itch, Lick & Scratch
These causes are in order of how commonly we see them at our Adelaide clinic:
- Atopic dermatitis
- Flea bite dermatitis
- Staph bacterial infection
- Malassezia fungal infection
- Mite infestation
- Contact allergy
- Food allergy
- Autoimmune disease
- Epitheliotropic lymphoma
Atopy is the classic skin allergy or eczema of dogs. It usually results from allergy to plants, pollens, moulds or dust mites. Read more here.
Features: Starts around 3-6months of age and worsens until 3 or 4 years old. Often worsens seasonally or after exposure to certain environments. More commonly affects the chin, ears, feet, armpits, groin and under tail but sometimes only one of these areas.
Atopy is often complicated by secondary fungal infections, pyoderma and ear infections.
Flea Bite Dermatitis
Flea bite remains extremely common due to the simple mistake of thinking that if you can’t see fleas they aren’t causing the problem. In fact, fleas bite nearly every unprotected dog or cat, and all itchy pets should be given flea control before doing anything else.
Features: worse in warmer times of year when fleas are more active. More commonly affects the back, the rump and the base of the tail but can be anywhere.
Bacterial Infection (Pyoderma)
Pyoderma is as infection of the hair follicles with Staphylococcal bacteria. It is extremely common either secondary to another skin problem or in certain susceptible breeds. However, once it starts it’s usually much worse than the original underlying cause.
Features: pyoderma usually looks like a pimply rash, but sometimes also crusty rings called epidermal collarettes or rapidly enlarging moist crusty lesions called hotspots. Lesions can occur anywhere.
Overgrowth of skin Malassezia fungi is another secondary infection that requires its own special treatment.
Features: a greasy, smelly dermatitis of folded areas like armpits, groin, ears, feet and under the tail. Has a very similar distribution to atopic dermatitis (above) and often shares its causes.
There are several mites that can cause skin problems:
- Sarcoptic mange mites burrow in the skin and create a severe itch, especially of the belly, elbows, hocks and ear flaps (also called fox mange)
- Demodex mites cause patchy hair loss anywhere but produce minimal itch, commonly in puppies
- Cheyletiella mites produce a severe flaky dandruff and itchy coat (see pattern below)
- Ear mites create smelly and itchy ears
Hypersensitivity & Contact Allergy
Hypersensitivity or contact allergy is often suspected, but rarely proven.
Features: a dermatitis worse in areas that make contact with the suspected substance. This might be the paws if it is a plant or the back if a shampoo, et cetera. It should subside when the substance is excluded.
Food allergy is a severe skin or gastrointestinal response to allergens found in food. Thankfully, despite being talked about frequently, it is not as common as most other causes of itching.
Features: unusual age of onset (very young or over 4 years), often with diarrhoea or vomiting. Skin signs are severe and respond poorly to treatment. The pattern is similar to atopic dermatitis.
Lastly, epitheliotropic lymphoma is an extremely rare skin cancer that cases severe itching. Autoimmune diseases like pemphigus also have severe skin effects including erosion, scabs and blisters.
Neither these, nor any other rare conditions should be considered until a vet has ruled out the common diseases and a skin biopsy has been performed.