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Dog allergies – causes, symptoms and treatment

01.01.2024 - Reading time: 7 minutes

An allergic dog scratches itself in a meadow

Around one in five dogs suffers from an allergy. Find out about the common symptoms and causes here.

You may be wondering why your dog has a dull coat or is moulting despite having a quality diet. Or why they are constantly scratching themself when you can’t see any parasites on them. Some dog owners even see sudden and inexplicable changes in the behaviour of their faithful companion. Few associate these symptoms with an allergy.


Detecting a dog’s allergy early and understanding it

Did you know that around one in five dogs suffer from allergies? This trend is on the rise. The reasons for this alarming development are varied and cross-allergies with different symptoms make a clear diagnosis more difficult. To fully understand a dog’s allergy, it is firstly important to find out the possible causes.

There are different types of allergies in dogs:

  • Environmental allergies: these are caused by certain environmental influences and are characterised by atopic dermatitis, the skin’s reaction to allergens. The main causes are pollens, grass, dust mites, feathers and mould.
  • Parasitic allergies: flea allergy dermatitis (FAD) is caused by flea saliva. A single bite can cause a severe allergic reaction in dogs. An allergy involving pimples can also occur.
  • Contact allergies: allergies to flea and tick collars, which, depending on how they are manufactured, are saturated with chemicals and neurotoxins, as well as allergies to natural essences such as neem oil, are all contact allergies. They occur through direct contact between the dog’s skin and the substance: for example, an allergy to rubber caused by a toy, or an allergy to metal caused by a feeding bowl.
  • Food allergies: not to be confused with food intolerances, the hypersensitivity reaction in a food allergy can come from foods such as milk, eggs, meat, fish, soya or cereals. The symptoms of a dog’s food allergy are often cutaneous.

Dog allergies – what are they?

Veterinary medicine, just like human medicine, defines an allergy as a tendency for the body to react to certain substances with a pathological reaction. These substances are harmless to the animal in themselves. The immune system is misled into thinking that they are toxic or indigestible on external contact (skin, respiratory tract) or oral contact (ingestion) and reacts by defending itself, putting the whole body on alert. The substances that provoke such a reaction are known as allergens. Some breeds of dog are more prone to allergies than others.

These include:

How can I tell if my dog has an allergy?

Dog allergy symptoms vary from one animal to another, even when the same allergen is present. In order to tell if your dog suffers from an allergy, ask yourself the following questions:

  • Does your dog always scratch certain areas of their body?
  • Do they have sores on their skin that they constantly lick?
  • Do they often have intestinal problems, maybe even diarrhoea and vomiting?
  • Do they suffer from inflammation of the ear or other inflammatory sites?
  • Do they have a runny nose and watery eyes?

Dogs sometimes develop a swollen head after being stung by an insect, such as a wasp or hornet. This is called Quincke’s edema, which is a veterinary emergency, as the swelling can, in some cases, extend to the neck and cause breathing difficulties. You therefore need to act quickly and take your faithful companion to the vet as soon as possible. After an injection of medicine, the swelling will disappear after a few hours. This allergic reaction may occur again if the dog comes into contact with the allergen again. Don’t leave your dog alone in the garden when it’s the season for bees, wasps and other stinging insects.

Eine Katze und ein Hund kuscheln liegend auf einen karierten Decke

Can a dog be allergic to cats?

Just like humans, dogs can be allergic to pets, such as cats. Do you have several pets, including at least one dog and one cat? If your dog regularly scratches or licks itself excessively, this may be due to itching caused by an allergy to your cat. Once allergens such as parasites or food intolerance have been ruled out, your vet can carry out an allergy test, which may or may not confirm your suspicion. If you are able, you could also ask someone to look after your cat for one or two weeks. If your dog’s symptoms disappear during this period, you won’t have a solution for the problem but at least you will know the cause.

What should I do if my dog is allergic to dust mites?

Dust mites are tiny arachnids that live in our homes, usually on carpets, sofas, bedding and curtains. Present all year round, they trigger allergies in some people as well as in dogs. The notorious dust allergies are in fact allergies to dust mites.

The most common symptoms are:

  • Itchiness
  • Excessive licking
  • Sneezing
  • Runny eyes
  • A cough

As these symptoms may be caused by other allergies and various diseases, it is often difficult to detect a dog’s allergy to dust mites. Different allergy tests, such as a serum allergy test and intradermal allergy test allow vets to make a diagnosis.

What can a vet do to diagnose a dog’s allergy?

If you suspect that your dog has an allergy, it is best to consult a vet or a veterinary clinic that specialises in allergies. A great deal of experience and additional training are needed to correctly diagnose allergies in dogs. Describe all the symptoms you have seen in your pet to the vet. Bear in mind that allergies to flea saliva and certain environmental allergies such as allergy to pollen are seasonal or may only appear at certain times of the year. There are several ways a vet can diagnose an allergy in a dog: blood tests, intradermal skin tests, elimination diet in the case of food allergies and intolerances.

Experience in veterinary diagnostics has shown that blood and intradermal tests alone give no reliable indication of a dog’s allergic condition. A vet will often make a diagnosis through process of clinical elimination, gradually ruling out illnesses with the same symptoms. Blood tests and allergy tests can provide additional indications for diagnosis. The cost of the tests varies from one veterinary clinic to another.

If a food intolerance is suspected, an elimination diet is prescribed. The first thing to do is to give the dog meat it has never eaten, or only eaten occasionally. For example, ostrich or horse meat with carbohydrates. If the dog’s symptoms improve during this strict diet, you should add other ingredients gradually to determine the cause of the problems. In all cases, this diet should be monitored by an expert to detect undesirable side-effects or other symptoms of deficiency in good time.

Treatment of allergies in dogs

Once an allergy is confirmed by the vet, there are several solutions depending on the allergen. In the event of serious problems, your vet may first administer medication to relieve your dog: antihistamines, corticoids, antipruritics. If the allergy is an intolerance to certain ingredients in the dog’s food, such as certain proteins, gluten or carbohydrates, the diet should be changed in a targeted and systematic way.

You can switch to a new diet with:

  • Non-contaminated hypoallergenic dog food (PCR test) from specialist shops.
  • Hydrolysed diets: the proteins in the food are broken down into molecular components so that the allergic dog’s immune system cannot detect them and attack them.
  • BARF (Biologically Appropriate Raw Food): raw food consisting mainly of raw meat and vegetables enriched with minerals and supplements according to the dog’s needs.

BARF is based on the use of natural ingredients (meat, vegetables and fruit), which make up the majority of the diet. To avoid dietary errors that could lead to deficiency symptoms, you should consult a veterinary nutritionist or naturopath right from the start to draw up a nutritional plan.

The following points are particularly important to ensure that dietary changes are effective:

  • your pet should be on their special diet at least 8 to 10 weeks before you can judge its effectiveness.
  • The food you choose should exclusively contain ingredients to which your dog is not allergic.
  • The food should not contain any preservatives or other additives.
  • Be strict – no exceptions allowed! This particularly applies to your choice of treats.

In the case of environmental allergies, desensitisation is the most effective method. However, the process is long and quite expensive. The younger the dog, the higher the chance of success. Desensitisation is generally done by injection, but sublingual desensitisation is also possible.
If your four-legged friend is allergic to flea bites, a flea treatment is required. If you know that your dog suffers from a parasitic allergy, it is important to prevent the reappearance of fleas by using appropriate products.


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