Warning Signs for Allergies in Dogs

Some breeds are more susceptible to allergies. However, no dog is free from allergies. Here are the warning signs that indicate that a dog is allergic.
Warning Signs for Allergies in Dogs
Georgelin Espinoza Medina

Reviewed and approved by the biologist Georgelin Espinoza Medina.

Last update: 18 November, 2023

An allergy is an exaggerated reaction of the body to substances that are normally tolerated, and it’s a reaction that shouldn’t occur. It occurs because the immune system’s functions are altered, and it detects these molecules as foreign. As in humans, dogs can also suffer from allergies. Do you know the warning signs for allergies in dogs?

Many breeds are affected by allergies, and these can occur at different ages. There are also different substances involved. However, there are distinctive signs that help us identify if a dog is allergic. Here, we’ll tell you all about them, as well as what you should do in these cases to improve your pet’s health.

Allergies in dogs

The different allergic reactions in dogs occur against various molecules, called allergens. These particles are harmless for most people and only affect those with allergies, where they cause their characteristic inflammatory processes. Allergens come either from food, the environment or medications. In addition, there are cases of response to more than one molecule.

Food allergies have a low incidence. The allergens that cause them are large proteins. The most frequent include milk, wheat, egg, fish, soy and others. In a study conducted at the University of Chile between 2009 and 2012, a 0.8% frequency of these pathologies was obtained in dogs from 4 months to 14 years of age.

Environmental allergies can occur seasonally or constantly, based on the source of the allergens. They are caused by different substances such as house dust mites, dust, pollen, certain plants, fungi and insects.

Studies carried out in Andalusia showed the most common allergens in dogs with atopic dermatitis. In this case, the protagonists were different species of mites, followed by olive tree pollen, fleas and dust. Allergies to more than 1 molecule were also observed.

A dog smiling.

What are the warning signs for allergies in dogs?

There are different signs that could show that your pet may be suffering from allergies, and here they are:

  • Pruritus: This is the most common occurrence in any type of allergy. It’s observed as redness and inflammation of the skin – usually on the face, ears, armpits, groin and near the anus. Scratches, bites and the dog sliding along on its backside are evident. In addition, there may be hair loss and loss of color in the most affected areas as a result of constant licking and biting.
  • Otitis: This is the most frequent secondary pathology related to allergies in dogs.
  • Red eyes: The dog’s eyes can also be affected with redness and tearing.
  • Gastrointestinal problems: Other warning signs in an allergic dog are digestive system disorders such as vomiting, diarrhea and flatulence.
  • Respiratory disorders: coughing, difficulty breathing and sneezing may occur.
  • In rare cases, acute allergic reactions may also occur, with facial swelling or even anaphylactic shock. The latter requires immediate treatment, as the dog’s life is in danger.

What to do when faced with the warning signs of a dog with allergies?

If we suspect that our dog is suffering from allergies, we need expert guidance. Therefore, we must go to the veterinarian for them to make the final diagnosis and recommend the most appropriate treatment.


The diagnosis of allergies isn’t so easy, as it can be a long process. The first thing the veterinarian will do is a thorough investigation of the symptoms. In addition, they’ll rule out other causes or pathogens, such as parasites. If the possible options are eliminated and the signs are treated, an elimination or exclusion diet is then performed to see if there’s a food allergy.

This diet is performed for a minimum of 8 weeks. During this time, the dog is offered foods that it hasn’t consumed before, in order to purify its body of possible allergens ingested. Only one source of protein and one of carbohydrates (rice or potato with skin) is provided. A home diet can be established or a commercial diet can be chosen.

The veterinarian also makes a list of all the regular foods in the dog’s diet. If an improvement in health is observed after this elimination period, a provocation stage is performed, in which the animal is offered its usual foods in order to test the allergy. This is carried out for another 7 to 15 days. If symptoms reappear, the elimination menu is started again.

If the elimination diet hasn’t given definitive results of the food allergy, skin or serological tests can be performed to try to detect sensitivity to environmental molecules such as pollen, mites, dust, fleas, among others.


A happy dog.

Due to the variety of symptoms that can appear in each dog, the treatment is adapted to the patient. There’s no definitive cure for allergies, we only try to eliminate or reduce the clinical signs and improve the quality of life.

The most important thing is to try to ensure that pet doesn’t remain in contact with the allergen that causes the inflammatory process. Therefore, adequate food should be provided or its surroundings should be modified, as the case may be. Maintaining cleanliness is also crucial. In addition, attention should be paid to the ears and they should be cleaned regularly. Remember that treatment should be provided by your veterinarian.

In short, the warning signs of an allergic dog are varied, depending on the source of the allergen and the individual response of each pet. Paying attention to details can make a difference and help you achieve a proper diagnosis, always in the hands of a specialist. Although it’s a long process, the owner’s commitment is fundamental to achieve the dog’s welfare, and it’s certainly worth the effort.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

  • Brazis, P., Queralt, M., Fondati, A., & Puigdemont, A. (2000). Alergia e intolerancia alimentaria en el perro y el gato. Consulta Revista Veterinaria, 8(72), 95-98.
  • Cajas, C. (2014). Descripción de casos de alergia alimentaria en perros. [Tesis de Grado, Universidad de Chile]. https://repositorio.uchile.cl/handle/2250/132058
  • Córdova, E., & Trigo, F. (1999). Hipersensibilidad alimentaria canina. Veterinaria México, 30(1), 67-77.
  • Pérez-Aranda, M., Blanco, B., Hernández, E., Ginel, P. (2016). Resultados del test intradérmico en perros con dermatitis atópica: estudio retrospectivo de 176 casos en Andalucía. Clínica Veterinaria de Pequeños Animales, 36(4), 285-292.
  • Rejas, J. (2008). Dermatitis y reacciones adversas a los alimentos. Revista Electrónica de Veterinaria, IX(5), 1-16.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.