By Dial A Vet Veterinary Team
Itchy skin is one of the most common reasons Australian dogs visit the vet, and allergies are behind a large share of those visits. Most allergic dogs fall into one or more of three groups: flea allergy, environmental allergy (atopic dermatitis) and food allergy. Some also react to plants they lie on, such as the creeping groundcover Tradescantia (wandering trad) that grows in many Australian backyards. Allergies cannot usually be cured, but with the right diagnosis most dogs can be kept comfortable, and the constant scratching, infections and sleepless nights can stop.
Key takeaways
- The main causes of skin allergy in dogs are fleas, environmental allergens, food and, less often, contact with plants or chemicals.
- Where the itch is on the body, and whether it is seasonal, helps point to the cause.
- Secondary bacterial and yeast infections are common and make itch much worse.
- Allergies are managed, not cured, often with a combination of approaches.
- Never use human medicines, tea tree oil or other essential oils on itchy dogs without vet advice.
The main types of skin allergy
Flea allergy dermatitis
A reaction to flea saliva. Itch and scabs concentrate over the lower back, tail base and back of the thighs. One bite can trigger days of itch. See flea allergy dermatitis in dogs.
Environmental allergy (atopic dermatitis)
A genetic tendency to react to pollens, grasses, dust mites and moulds. Signs usually start between six months and three years of age. Itch affects the paws, face, ears, armpits and belly, and is often seasonal at first, becoming year round over time. Breeds such as Labradors, golden retrievers, West Highland white terriers, French bulldogs, Staffordshire bull terriers and shar peis are commonly affected.
Food allergy
An immune reaction to a dietary protein, often one the dog has eaten for a long time. The itch pattern is similar to environmental allergy but tends to be year round, sometimes with gut signs.
Contact allergy
Less common. Reactions occur where skin touches the trigger, usually the thinly furred belly, chin, feet and groin. In Australia, Tradescantia is a well-known culprit. Some dogs react to certain carpets, cleaning products or plastic bowls.
Signs of skin allergy
- Scratching, licking, chewing and rubbing
- Red skin, bumps or rash
- Hair loss and broken hairs
- Saliva staining of paws
- Recurrent ear infections
- Greasy, smelly or flaky skin
- Darkened, thickened skin in long-term cases
- Hot spots: sudden, moist, painful sores
When to see a vet
Emergency now: sudden swelling of the face or muzzle, widespread hives with breathing difficulty, vomiting, weakness or collapse, which may follow insect stings, vaccines or other exposures.
Same day: a fast-spreading hot spot, pus, open wounds, a painful swollen ear, or a dog that cannot rest because of itch.
Book a visit: itch lasting more than a week or two, recurring ear problems, or patchy hair loss.
What to do
- Check that every pet in the house is on effective flea control.
- Rinse paws and belly with plain water after walks, and dry them well.
- Remove Tradescantia from the yard if your dog has a belly or feet rash.
- Keep a diary of itch, season, diet and new products.
- Use a cone or soft suit to stop self-trauma until your dog is seen.
- Do not use tea tree oil, essential oils or human creams, and do not give human antihistamines or steroids unless your vet advises.
How vets diagnose skin allergies
There is no single test. Vets work through the possibilities: controlling fleas, checking skin scrapings and tape samples for mites, bacteria and yeast, and treating infections. A food elimination trial checks for food allergy. Environmental allergy is diagnosed once other causes are ruled out, and intradermal or blood allergy testing is then used to select allergens for immunotherapy, not to make the diagnosis itself.
How vets manage skin allergies
Most dogs need a combination plan, which may include:
- Strict flea control
- Treatment of bacterial and yeast infections
- Medicated shampoos and topical products to repair the skin barrier
- Prescription anti-itch medicines chosen by your vet
- Allergen immunotherapy (allergy injections or oral drops) for environmental allergy
- Diet changes for food allergy, and essential fatty acid support
Flare-ups are common, so regular rechecks help adjust the plan through the seasons.
Prevention
- Year-round flea prevention for every pet
- Regular bathing with a vet-recommended shampoo if advised
- Prompt treatment of ear and skin infections before they become chronic
- Keeping dogs off known trigger plants
FAQ
Can dogs grow out of allergies?
Rarely. Environmental allergies usually persist and may worsen over the first few years, which is why long-term plans matter.
Are allergy tests worth it?
They are useful for choosing immunotherapy once environmental allergy is diagnosed, but they cannot diagnose allergy on their own.
Is my dog's itch seasonal or year round?
Keeping a diary for a few months helps answer this, and it is one of the most useful things you can bring to your vet.
Talk with a vet
Living with an itchy dog is exhausting for everyone. A Dial A Vet consult can help you work out the likely cause and next steps. Facial swelling with breathing difficulty or collapse needs an in-person emergency vet now.
References
- Olivry T, et al. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA). BMC Veterinary Research, 2015
- Merck Veterinary Manual: Atopic Dermatitis in Animals
- Merck Veterinary Manual: Flea Allergy Dermatitis in Dogs and Cats
- Merck Veterinary Manual: Contact Dermatitis in Animals
Disclaimer: Educational only. This page does not replace an examination or advice from your own veterinarian. Persistent itch deserves a proper vet assessment.
