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Common skin allergies in dogs

Approx. 8 minutes read

All dogs scratch, but if your poor pup is itching and scratching all the time, it’s likely that you have an unhappy, uncomfortable canine pal who just cannot get any relief from his persistent itching. Why do dogs scratch? The cause is just beneath your dog’s surface – an allergy that’s crept its way into his skin from one (or more) of a few sources.

Is your dog’s allergy seasonal?

Seasonal allergies occur when changes in the weather cause changes in your dog’s skin. The time of the year that your dog suffers more from itchy skin can tell you a lot about why he’s scratching so much. If your furry friend starts to get itchy in the springtime, he may well be suffering from seasonal allergies, but what about a dog that starts scratching in winter? Perhaps his skin is dry and flaky because of the decrease in moisture in the air. If your dog starts scratching more when it’s hot and humid, it’s likely – especially if he’s a wrinkly dog like a bulldog, shar-pei, bloodhound, Neapolitan mastiff or pug – that he has a yeast overgrowth or skin infection because his skinfolds trap moisture and bacteria, creating the pawfect conditions for an infection.

What does a dog skin allergy look like?

Skin allergies and yeast infections may both cause your dog to itch and scratch, but it’s important to distinguish between the two because the success of treating your dog’s scratching depends on it! The treatments for allergies vs dry skin vs yeast overgrowth are vastly different, but your veterinarian will be able to help you identify the cause of your dog’s scratching. If it’s a skin allergy, it can be identified by:

  • red skin
  • welts or hives (raised bumps in the skin)
  • inflammation
  • swelling in the affected area
  • compulsive licking of the affected area

Top 4 skin allergies in dogs

Skin allergies are one of the most common reasons why pet pawrents bring their furry friends in to see the vet. Since there are a number of different types of skin allergies – some of which share the same symptoms – it’s crucial that pet owners can give the veterinarian enough information to determine the cause of their dog’s skin allergy. Information such as when the itching started and how long it’s been going on for; what other symptoms the dog has been having (such as vomiting and/or diarrhoea); whether they spend most of their day indoors or outdoors; and how up-to-date their tick and flea medication is.

The four most common skin allergies in dogs are:

  • Flea allergy
  • Atopy
  • Food allergy
  • Contact allergy

Here, we look at each allergy and how to figure out which allergy your poor pooch may be suffering from.

Flea allergy

Flea allergies are quite common in dogs, so this is a great place to start when determining why your dog is scratching so much. A flea allergy doesn’t require a flea infestation to become a problem – in fact, your dog could show an allergic reaction from a single flea bite. This will cause immediate itching that can last long after the flea has gone.

The most common indicator of a flea allergy is that your dog will be biting and scratching at his rump area at the base of his tail. It’s also more likely to occur in the warmer months, but this is not a hard-and-fast rule. In sunny South Africa, fleas occur all year round! Preventing a flea allergy is as simple as keeping your dog’s tick and flea medication up to date. A topical flea treatment or spot-on will kill parasites on contact, while chewable tablets will kill parasites on the first bite and protect your pup for an extended period of time.

Diagnosing and treating a flea allergy

A flea allergy is one of the easiest to detect, as the presence of fleas, eggs and/or flea dirt on your dog’s skin and fur will be the giveaway. Your vet can easily confirm the diagnosis by conducting an intradermal skin test. The best treatment for a flea allergy is a medicated bath and Benadryl for the itching. Ask your vet’s advice on the best topical flea treatment for your dog’s specific case.

It’s also a good idea to treat your dog’s environment for fleas by vacuuming thoroughly and then using a flea powder on your dog’s common areas like his bed and favourite snoozing places.


Canine atopic dermatitis (atopy) is the most common cause of pet allergies. It’s a hereditary skin disease – meaning that your dog may be genetically predisposed to allergic skin reactions from multiple allergens in the environment. Whether it’s grass, pollen, seeds, insects, trees, dust, etc. – it’s the dog’s reactivity that defines the condition, rather than one specific allergen. His immune system is simply more sensitive to common allergens, so he will suffer from skin allergies more often than dogs without atopy.

Atopy may affect your dog all year ‘round, but it often flares up in the spring and summertime when the environmental allergen load is the highest (from dust and pollen). He will be itching and scratching a lot, but will also show signs of face rubbing and belly scratching – accompanied by redness and inflammation in these areas. Atopy can begin at any age, but mostly starts to show symptoms from the ages of one to four years old. If left undiagnosed and untreated, over time, atopy can make dogs more reactive to more and more allergens, which can turn this allergy into a full-time problem – grass and pollen in warm weather, and dust mites and other cool-weather allergens in winter – resulting in year-round itching.

Diagnosing and treating atopy

Since canine atopic dermatitis is built into a dog’s DNA, it can be difficult at first to diagnose it as such because of the amount of overlap in symptoms with other types of skin allergies. However, your vet will be able to run all the necessary tests (and rule out other causes) as part of an extensive work-up to diagnose whether your dog’s itchy, scratchy skin is as a result of atopy.

If your dog is indeed diagnosed with atopy, it is a condition that will need to be managed for his whole life. He may receive allergen-specific treatments like immunotherapy, but managing atopy requires a combination of medications, sensitive dog food, shampoos and strict parasite management.

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Dog food allergy

Dog food allergies are fairly common, but not as common as contact allergies. Most dog food allergies are to natural ingredients such as various meats, eggs, grains, milk, etc. They can develop at any time – even if your dog has been eating and thriving on the same food for a long time – and their onset can be quite sudden.

Most dog skin allergies are not related to food allergies, but the overlap in symptoms means that diagnosing this type of allergy can take some trial and error. Dog food allergy symptoms may include gastrointestinal issues like diarrhoea and vomiting, with itchy skin being just another symptom of food allergies. It’s distinguishable from contact allergies in that a dog’s skin may itch all year ‘round – not only during spring and autumn. Plus, if the itching and scratching is not soothed and relieved with regular baths, it is likely to be caused by a food allergy.

Diagnosing and treating food allergies in dogs

Food allergies, unlike atopy, cannot be diagnosed with blood or skin tests. The only way to diagnose a food allergy is by conducting a novel food trial. This means giving your dog food containing ingredients he’s never had before, or by eliminating certain ingredients from his food – one by one – to see whether his allergy symptoms go away.

This is neither a quick nor an easy process, and requires a food transition period with high quality dog foods indicated for sensitive tummies and food allergies. Each dog’s response to the various dog food brands will be different, and it requires a process of elimination to find the dog food that your dog is least allergic to.

Premium dog foods have higher quality ingredients than economic brands, but if you suspect that your dog has a food allergy, it’s a good idea to work with your veterinarian to determine the root cause and find a healthy nutrition alternative.

Contact allergy

A contact allergy (also known as contact hypersensitivity or contact dermatitis) occurs when your dog is allergic to something that he has come into contact with. This is usually immediate and, along with itching, you’ll likely see raised red bumps or welts.

Diagnosing and treating contact allergies in dogs

If you suspect your dog has a contact allergy, you need to identify what the cause is and eliminate it from his environment. This is much easier said than done, but the suddenness of a contact allergy reaction means that eliminating the causes of your dog’s reaction involves retracing your dog’s steps to the last few hours of his day. For instance, if you walked him in a new park, planted new plants in your garden, put down fertiliser, used a new floor cleaner, etc. These may all be the culprits in your dog’s contact allergies.

Contact dermatitis can be the easiest allergy to treat, but it does require a little bit of detective work to figure out what your dog came into contact with. Contact allergies rarely require a visit to the vet – if you can identify and remove the cause of the reaction from your dog’s environment, then the allergy is likely to clear up on its own.

How can I treat my dog’s skin allergies?

If you’re wondering if dog allergies can go away on their own or need to be treated with medication or lifestyle changes, this depends entirely on the cause of the allergy. As we’ve seen, dogs’ skin allergies can be seasonal, food-based, hereditary, environmental (contact dermatitis) or caused by ectoparasites. With the correct diagnosis of the allergies and identifying the cause of your dog’s scratching, your vet will either help you to manage the symptoms or suggest you make changes to your dog’s environment.

Hopefully you can restore your dog’s comfort and ensure his top health and wellbeing!

Our furry friends can’t always tell us what’s wrong or what they need to feel better, but that’s why Pet Hero offers the latest in vet-approved content. The more you know, the better prepared you’ll be to help your pets when they need it. Sign up for our newsletter so you don’t miss vital Pet Hero articles as well as our latest specials, promotions and competitions – delivered straight to your inbox!

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