Dermatitis in dogs and cats: symptoms, causes and treatment

Summary

What is dermatitis?

Dermatitis is a general term used to describe a group of conditions in which the skin becomes chronically itchy and inflamed. Dermatitis has many causes, which fall under the general categories of infectious dermatitis (bacterial/fungal), parasitic dermatitis (fleas, mites) or allergic dermatitis, with often some overlap in these categories. Allergic dermatitis in dogs and cats can be triggered by environmental allergens, such as in atopic dermatitis, when exposure to an environmental allergen causes an inflammatory response and contact dermatitis, where affected animals experience a reaction to compounds directly in contact with the skin.

This article focuses mainly on atopic dermatitis and contact dermatitis. Although both of these forms are the result of an allergic reaction to a skin irritant and are often grouped together, it is important to recognise that they are two distinct diseases and need to be diagnosed and treated accordingly.

Other common allergic triggers for dogs or cats are flea allergy dermatitis, where contact with fleas can set off an intense itch and inflammation, food allergy dermatitis, where skin allergy signs stem from a dietary trigger, and secondary bacterial or yeast dermatitis.

Expert advice from Dr Felicia:

Dogs and cats regularly visiting the vet for inflamed, itchy skin may have allergies contributing to their signs. The breed, age and distribution of lesions provide helpful hints for what the ideal next steps may be.

Atopic dermatitis in dogs and cats

This is the most common type of dermatitis in dogs and cats, occurring when exposure to an environmental allergen results in an inflammatory response (the over-production of antibodies by the immune system) that affects the skin. It is a pruritic disease, meaning that it causes extreme itchiness and provokes the urge to scratch.

Atopic dermatitis in dogs and cats can develop in response to normally harmless substances like grass, mould spores, house dust mites, and other environmental allergens. The substance may not have previously caused any obvious problems. Sensitivity to the substance can develop slowly over time and then come on suddenly without warning. Most allergic reactions require a period of repeated exposure and skin sensitisation, which can take anywhere from 6 months to 2 years to develop.

Dogs are more prone to this condition than cats. Dogs generally show signs of the condition between 3 months and 6 years of age, though these can be so mild during the first year or so that they do not become clinically apparent before the dog’s third year. Feline atopic dermatitis is similar to that of dogs.  The age of onset in cats is variable, but is generally under 5 years.

The most commonly affected areas in both dogs and cats are the ears, wrists, ankles, muzzle, underarms, groin, around the eyes and between the toes.

Learn more about skin allergies in dogs and hair loss in dogs.

Expert advice from Dr Felicia:

Atopic dermatitis is increasing in prevalence, especially in dogs. These patients require an acute flare management plan as well as ongoing maintenance to hopefully reduce the incidence of flares. This is a lifelong disease that needs proactive care.

Contact dermatitis in dogs and cats

Contact dermatitis occurs when actual physical contact is made with a chemical or other irritating substance, causing an inflammatory response in the body (the over-production of antibodies by the immune system) that affects the skin. This occurs far less frequently than atopic dermatitis in both dogs and cats.

Irritant contact dermatitis can occur the first time a pet is exposed to a substance that irritates or damages the skin. Allergic contact dermatitis is different, as it usually requires previous exposure and sensitisation before a reaction occurs.

While atopic dermatitis is widespread and affects most of the body, contact dermatitis typically affects the areas that are less protected by hair, including the feet, nose, chin, lips, jointed areas (‘knees’) and the underside of the abdomen. In addition, ulcers may occur in cases of contact dermatitis.

Expert advice from Dr Felicia:

Dogs with contact dermatitis may not normally be prone to skin disease, though some patients with sensitive skin are prone to this as well. Signs usually come up quickly after exposure and resolve with removal of the allergen.

Cost of skin allergies for dogs

Skin infections and allergies were the most common health issue experienced by dogs 2024, according to PetSure claims data.

Cost of skin allergies for cats

Skin infections and allergies were the third most common health issue experienced by cats in 2024, according to PetSure claims data.

^ØBased on PetSure claims data, 2024 calendar year. Reimbursement for these claims under a pet insurance policy would be subject to limits, such as annual benefit limits or sub-limits, benefit percentage, applicable waiting periods and any applicable excess. Cover is subject to the policy terms and conditions. You should consider the relevant Product Disclosure Statement or policy wording available from the relevant provider. Please note that values calculated are based on all claims for that condition and medically related conditions in each calendar year.

Symptoms of dermatitis in dogs and cats

Dermatitis is typically associated with redness, swelling, skin lesions, blisters and/or rashes of the skin. The resulting discomfort will usually result in your dog or cat licking, biting, or scratching excessively at the affected area, which can lead to a secondary bacterial infection.

Often the symptoms of atopic dermatitis progressively worsen with time and increased age, and become more severe during certain seasons.

The typical symptoms of dermatitis include:

• Itching excessively (pruritus is the characteristic sign of atopic dermatitis)
• Skin rash or infection, with red bumps and inflammation
• Blister-like lesions
• Hives
• Crusting, thickening and scaling of the skin
• Hair loss
• Scratching continuously, without finding relief
• Red or irritated ears
• Irritated skin in armpits, groin, between toes, around eyes, ears or muzzle areas
• Skin infections
• Ear infections (often chronic and recurring)
• Rubbing themselves along the walls or carpet
• Licking, especially around the face, paws, and underarms
• Discomfort or pain
• Broken or bleeding skin, from excessive scratching, biting or chewing at the paws, armpits or groin
• Flaky, scaly or greasy skin
• A foul odour to the skin (specifically in dogs)
• Saliva stains or discoloured fur (from excessive licking) on forelimbs, paws, or in between toes
• Moaning or whining while scratching
• Signs of being an allergy sufferer such as profuse wheezing, sniffing, breathing difficulties, watery eyes or skin problems.

Expert advice from Dr Felicia:

Chronically itchy and irritated skin has a major impact on quality of life, as often itchy pets find it hard to sleep, will need to stop and itch while playing, walking or even eating.

Causes of dermatitis in dogs and cats

Common irritants linked to contact dermatitis include:

• Specific plant-based irritants such as poison ivy sap
• Road salt (for melting ice)
• Detergents, soaps and solvents
• Acids and alkalis
• Petroleum-based substances such as fertilisers, perfumes and petroleum jelly.

Expert advice from Dr Felicia:

Contact reaction triggers tend to be very obvious as they are often intentionally applied to the skin, in the form of medications, shampoos or soaps.

Common irritants linked to atopic (allergic) dermatitis include:

• Airborne pollens (grasses, weeds, plants, trees, etc.)
• Carpet deodorisers or household cleansers
• Certain metals (such as nickel)
• Dyes
• Flea collars/powders and other treatments
• House dust mites
• Insecticides/pesticides and plant fertilisers
• Materials including plastic, rubber, wool, and leather
• Mould spores (indoor and outdoor)
• Soaps, detergents and shampoos
• Topical antibiotics
• Animal danders (skin flakes, dandruff).

Expert advice from Dr Felicia:

Atopic dermatitis triggers are harder to pinpoint and may require intradermal skin testing to confirm. Immunotherapy can help reduce the sensitivity of the immune system to these allergens.

Familial susceptibility to atopic dermatitis:

Early onset is often associated with a family history of skin allergies. This may lead the dog or cat to become more susceptible to allergens.

Genetic predisposition to atopic dermatitis:

There appears to be a genetic predisposition (inherited genes passed down through generations) for atopic dermatitis in certain dog breeds, but the prevalence within a breed largely depends on the genetic pool and region. Purebred cats may have a higher risk than domestic shorthaired cats.

Dog breeds with a predisposition for dermatitis include:

• Boston Terrier
• Boxer
• Dalmatian
• Lhasa Apso
• Shih Tzu
• West Highland White Terrier
• Wirehaired Fox Terrier
• Scottish Terrier
• Golden Retriever
• Labrador Retriever
• Chinese Shar-Pei

How is dermatitis in dogs and cats diagnosed?

Your veterinarian will take a comprehensive medical history and conduct a complete dermatologic and physical examination of the animal so as to determine the specific type of dog or cat dermatitis and identify its underlying cause.

Unfortunately, there are no tests that can definitively diagnose atopic dermatitis in dogs and cats. However, tests can be performed to differentiate the condition from other diseases with similar clinical signs, such as flea allergy, mosquito bite hypersensitivity, food allergy, autoimmune disease and parasites. The diagnosis of atopic dermatitis is made when other causes such as fleas, mites, ringworm, bacterial infection, yeast infection and food allergy have been ruled out.

Tests to exclude other conditions may include:

• Skin swabs/scrapings to check for microscopic parasites
• Faecal and blood analysis to rule out internal parasites
• Fungal cultures.

Additionally, allergy testing may be performed as a diagnostic aid. Allergy testing is useful in order to:

• Measure the levels of antibodies produced by the immune system
• Identify the allergen responsible for the reaction
• Formulate specific immunotherapy that targets the offending allergen.

Expert advice from Dr Felicia:

The amount of testing recommended will likely depend on the severity and duration of signs, as well as the client expectations. Many patients who are comfortable and well managed may not have a need for immunotherapy.

Prognosis

Atopic dermatitis is a chronic, life-long problem that requires ongoing management and treatment and regular progress checks. Over time or without treatment, atopic dermatitis usually gets worse, resulting in excessive licking, biting or scratching that can lead to hair loss, secondary bacterial skin infections and ear infections. This will have an increasingly negative effect on the animal’s quality of life and personality.

However, if the signs are recognised and the allergens identified early on, the condition can be effectively managed, and the animal’s comfort and well-being can be greatly improved.

Treatment of dermatitis in dogs and cats

Resolution of dermatitis requires identification of the underlying cause and treatment of secondary infections or other complications.

Atopic dermatitis treatment

• The vet will advise how to best avoid the trigger allergens. This may be the best option, but can only be accomplished if a specific allergen has been identified.
• Allergen-specific immunotherapy (ASIT) may be performed.
• Immunosuppressant medication may be effective in controlling itching associated with long-term skin allergies.
• Anti-itching sprays can be used over large body surfaces to control itching with minimal side effects.
• Antihistamines may be prescribed to control or reduce itching.
• Oral steroids may be prescribed for acute flare-ups with pruritus (itching) that is severe or too extensive to be controlled with topical formulations.
• Bathing the animal routinely in cool water with anti-itch and/or antimicrobial shampoos may help alleviate symptoms.

Ongoing management of atopic dermatitis

• Maintaining regular check-ups with the vet is the most important preventative measure that can be taken.
• If the animal is prone to biting or scratching, a cone (Elizabethan collar) or other alternative is recommended; this will also prevent ingestion of any topical treatments.

Expert advice from Dr Felicia:

Specific treatments will be tailored to the patient, lifestyle and the owner’s capacity and finances, and may require adjustment if the signs are persistent or not completely controlled with the existing plan.

Treatment for irritant contact dermatitis

Contact dermatitis may resolve if the trigger is identified and avoided, although some pets experience recurring flare-ups if they continue to come into contact with the irritant or allergen. The most effective way to manage the condition is to avoid exposure to irritants whenever possible, for example:

• Change brands of household detergent and pet shampoo to hypoallergenic brands
• Avoid using certain chemicals
• Remove a particular plant from the property
• Provide a glass or stainless-steel water/food bowl (instead of plastic, which may contain parabens)
• Provide toys that are rubber-free

The vet may prescribe anti-inflammatory treatments, such as topical or oral corticosteroids or antihistamines, to control the itching and other side-effects associated with the allergen. There are also medicated shampoos and sprays that can provide temporary relief from itching.

Because it is difficult to predict the costs of veterinary care, it can help to have measures in place to help prepare for the unexpected. Pet insurance can help by covering a portion of the eligible vet bill if the unexpected does happen.

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In conclusion

Dermatitis is a common skin allergy in dogs, also occurring, although less frequently, in cats. Atopic dermatitis is a chronic, inflammatory skin disease associated with allergies to particular substances. The animal develops a hypersensitivity to the trigger allergen slowly, by repeated exposure over time. Common allergens include airborne pollens, mould spores, house dust mite, soaps, detergents and shampoos. These cause symptoms such as intense itchiness, excessive scratching, hair loss and inflamed sores to the skin of various parts of the body.

Contact dermatitis is a relatively rare skin disease that can occur when a dog or cat makes physical contact with a chemical or other irritating substance that causes an instantaneous adverse reaction.

The treatment recommended by the vet will depend on the cause of the dermatitis and may include medications to relieve itchiness and other symptoms, avoidance of the allergen (if possible) and immunotherapy to desensitise the animal to the allergen. Typically, dermatitis can be managed but not cured, and ongoing veterinary consultations are required.

Sources

“Dermatitis in Animals”, MSD Veterinary Manual, https://www.msdvetmanual.com/integumentary-system/integumentary-system-introduction/dermatitis-in-animals. Accessed 7 Jul 2026

“Atopic Dermatitis in Dogs”, Merck Veterinary Manual, https://www.merckvetmanual.com/integumentary-system/atopic-skin-conditions-in-dogs-and-cats/atopic-dermatitis-in-dogs. Accessed 7 Jul 2026

“Contact Dermatitis – Small and Large Animals”, Small and Large Animal Dermatology Handbook, University of Minnesota Libraries Publishing, https://open.lib.umn.edu/animaldermatology/chapter/contact-allergy-small-and-large-animals/. Accessed 7 Jul 2026

“Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA)”, BMC Veterinary Research, https://pubmed.ncbi.nlm.nih.gov/26276051/. Accessed 7 Jul 2026