When a dog scratches often, parasites are often the first thing that people think of as the cause. However, in addition to parasites, there are also other causes for itching, such as allergies. Allergies in dogs are not uncommon and the number of allergic conditions is on the rise.
Which Allergies in Dogs Are Most Common?
The most common allergies in dogs are:
All three allergies manifest themselves in the dog with more or less the same symptoms. Therefore, the diagnosis can often be difficult. In addition, a dog can have several allergies at the same time.
A flea allergy is not breed-specific. In addition, dogs of both sexes are equally affected by this. The allergy is usually caused by the not-so-cat flea (Ctenocephalides felis) which does not only occur in cats, but other flea species can also cause the allergy. Flea allergy can occur at any age except before the age of six months. Flea allergies are caused by proteins in flea saliva. The flea not only sucks the dog’s blood but also injects flea saliva at the same time. This is either an immediate reaction (type I reaction) where the body responds within 30 minutes or a delayed reaction (type IV reaction) where symptoms only appear after hours to 2 days. Usually, dogs that have little contact with fleas suffer from an allergy. Dogs that come into frequent contact with fleas can develop a tolerance.
Atopy (environmental allergy) affects about 15% of dogs. Unlike flea allergies, some breeds are prone to atopy. These include:
- golden retriever
- Labrador Retriever
- German Shepherd
- English Bulldog
- English and Irish Setter
- Shar Pei
The allergy usually occurs between the first and third year of life, very rarely before the sixth month of life or in older dogs. A precondition for the development of atopy is the dog’s predisposition to react strongly to an allergen. These dogs react to harmless environmental substances such as pollen, grass, dust mites, and molds with a strong antibody formation. This triggers a massive inflammatory response with tissue damage. The symptoms are seasonal with reactions to grasses, for example. The allergens enter the body through the respiratory tract or the skin.back to menu ↑
There is no race or gender that has a specific predisposition to a food allergy. In addition, it can start at any age. A true food allergy requires a dog to eat a particular food for a long period of time before an overreaction occurs. A healthy animal develops an immunological tolerance to the ingredients in the feed. However, if the protective function of the intestinal mucosa is impaired, allergens can overcome the intestinal barrier and trigger an allergic reaction.
According to current knowledge, allergens in dogs are proteins or protein compounds of a certain size that occur in the food. Any protein can therefore lead to allergic reactions. The chance of this increases the more it is eaten. With us, the most common allergens are beef, milk and dairy products, eggs, wheat, and chicken. Food allergies involve immediate or delayed reactions. A combination of these reactions is also possible. The symptoms can thus appear within 30 minutes, several hours, or even days and weeks after ingesting the allergen.back to menu ↑
Symptoms of Allergies in Dogs
The symptoms of an allergy at a glance
- Itching: Your dog is constantly scratching.
- Gastrointestinal symptoms: Your four-legged friend is suffering from digestive disorders such as vomiting or abdominal pain.
- Inflammation: near the legs and ears.
The main symptom of all allergies is itching. In the case of a flea allergy, this mainly affects the rear half of the body, the back, the crotch, the base of the tail, the hind legs, and the abdomen. Dogs scratch and rub these spots, often resulting in a so-called hot spot. This is an inflamed and purulent wound caused by the intense itching itself. These spots become extra colonized with bacteria and yeast fungi, which makes the itching even worse.
In atopy and food allergy, the itch distribution pattern is very similar, making it difficult to distinguish. Itching occurs around the head, legs, armpits, abdomen, inner thighs, and ears. On the legs, inflammation develops in the area between the toes and the bottom of the legs. In addition, inflammation of the external auditory canal in the ears can occur. Bacteria and yeast fungi often settle on damaged skin and cause an infection (secondary infection) and additional itching. In case of food allergy, stomach and intestinal complaints can also occur, such as vomiting, diarrhea, flatulence severe abdominal pain, and unformed stools.back to menu ↑
Diagnosing Allergies in Dogs
How can the vet diagnose allergies in dogs?
This can be done using the methods below.
- exclusion diagnosis
- brucellin test;
- blood test;
- elimination diet.
Since the symptoms of the individual allergies are very similar, the diagnosis is challenging. In addition, a dog can suffer from several allergies at the same time. In addition, there are no easy-to-perform and reliable tests available to distinguish between allergies. An allergy is therefore diagnosed by means of an exclusion diagnosis. In addition, a detailed medical history and identification can already provide clues.
You should provide your vet with the following information in the history:
- Age when symptoms started
- Location of the itching or skin symptoms
- Presence of similar symptoms in littermates or parents of the dogs
- Seasonality of the symptoms.
- Flea allergy
Even if the symptoms do not indicate a flea allergy, it should be ruled out in the beginning. The vet examines the dog for fleas and flea faeces with a flea comb. The finding of this confirms the suspicion. An intradermal test may also be used for diagnosis. In this test, flea allergens and control chemicals are injected into the skin on the chest wall. Then, after 15-30 minutes, 4 to 6, 24, and 48 hours, it is checked whether allergic reactions occur. There are also blood tests for the diagnosis of flea allergy, but they only provide information about type I reactions. Diagnostic therapy is also possible. The dog and all animals living in the household are treated with appropriate anti-flea medicines. It is likely that you have a flea allergy if the treatment is successful.
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Allergies in Dogs: Food Allergy
To confirm or exclude a food allergy, only an elimination diet (exclusion diet) makes sense, according to the recommendations of dermatologists. In this diet, the dog should be fed one protein source and one carbohydrate source that he has never had for a period of at least eight weeks. Since he has not yet been in contact with these substances, he cannot react to them. During the diet period, the dog should not be given anything else to eat. Treats and rewards should consist of the ingredients intended for the diet.
Dermatologists recommend a home-cooked diet. If it is not possible for the dog owner to prepare the food for the diet himself, hydrolyzed diets are available. Here the components are so small that the body cannot recognize them as allergens. It is also possible to feed mono protein variants. During the diet, the symptoms should improve significantly. After the symptoms have disappeared, a challenge should be carried out with the food that was given before the diet. If the symptoms come back, that’s evidence of a food allergy.back to menu ↑
The diagnosis of atopy is made clinically and by excluding other diseases. Atopy can only be established when certain aspects have been clarified. The symptoms, age, itching pattern, and other points must be correct. In addition, other causes of itching should be carefully excluded. Now the vet can perform specific tests to identify the allergens causing the allergy. An intradermal test is very suitable, in which allergens are injected into the skin and the reactions to them are read. This test should always be performed by an experienced dermatologist. A blood allergy test is also possible, but it may show false-positive reactions.back to menu ↑
Treatment of allergies
The best treatment for allergies in dogs is to avoid the causative allergen, but this can be difficult depending on the allergy. The treatment of flea allergy consists of consistent flea control and prophylaxis of the dog. Other animals in the household should also be regularly treated against fleas so that the allergic dog comes into contact with fleas as little as possible. In addition, especially for allergy sufferers, treatment and thorough cleaning of the environment is necessary in case of flea infestation. If itching occurs, it can be treated with appropriate medicines to prevent secondary infections.
For food allergies, the identification of the causative allergen (eg beef) is beneficial as the dog can continue to be fed normally while avoiding the allergen. If the allergen cannot be found or if the dog reacts to different proteins, a hydrolyzed diet can be given. For some time now, insect-based protein food has also been on the market, which is a newer approach to diagnosis and therapy. The itching is much less treatable with preparations such as glucocorticoids or antihistamines. These drugs are not as effective for food allergies as they are for flea allergies or atopy. Secondary conditions such as ear infections and skin infections should also be treated.back to menu ↑
How is atopy treated?
Treating atopy is challenging because it is nearly impossible to avoid the causative allergen. If the itching is limited to a few months of the year, it is possible to treat the dog with antipruritic medication during this period. If the dog suffers from itching for a long time, desensitization is recommended. This is immunotherapy. The dog is given the allergens to which it reacts in increasing concentrations. The goal is to boost the dog’s immune system and achieve tolerance to allergens.
Unfortunately, this therapy does not always have the desired effect. Additional antipruritic therapy such as cortisone, antihistamines, cyclosporine, essential fatty acids, or oclacitinib may be required. A new therapeutic agent against itching in atopy has recently come on the market, a preparation with monoclonal antibodies. These antibodies capture the substance responsible for the itching in the atopy and are metabolized like the body’s own proteins. This form of therapy has proven to be very successful so far and is also very well tolerated.back to menu ↑
Prevention of Allergies in Dogs
Preventing allergies is difficult because many factors are involved in the onset of an allergy in dogs. If one dog is already known to have an allergy, others may follow. To avoid a flea allergy, one should pay attention to a consistent flea and parasite treatment. It is also advisable to feed a dog varied with multiple protein sources. However, exotic proteins should be avoided as they can be useful as a basis for a diet in case of an allergy. Since atopy is a hereditary form of allergy, it is not recommended to breed with allergic animals.