allergies

Allergy to pets: Causes

Generality

In susceptible people, contact with cats, dogs and other domestic animals can trigger a violent hypersensitivity reaction of the immune system, which mainly affects the respiratory tract.

In particular, the allergy to domestic animals is triggered by exposure to all the protein components ( allergens ) contained in fallen hair, flakes of dead skin, saliva or urine. In fact, allergens are microscopic and light particles that spread easily in the air and remain in an environment for a long time; therefore, direct contact with the animal is not necessary. Indeed, those who are particularly sensitive may experience an allergic reaction even when approaching people who have come directly into contact with an animal or when they enter a room where they have not stayed for months. The most "dangerous" animal, from this point of view, is the cat, given that its saliva and dandruff contain a strong allergen; to follow, the dog and the horse . Occasionally, even hamsters, guinea pigs, rabbits, poultry, cattle and pigs can cause an immune response. However, it must be considered that the pet is often a "fake allergen": it is not the contact with its hair, saliva or dandruff that causes allergy, but that with the mites that nest in its hair. In this case, the animal is a simple vehicle of the true culprit. The allergy to domestic animals manifests itself with typical symptoms of allergic rhinitis or asthma, such as dyspnea and breathing difficulties, and can be associated with skin reactions (atopic dermatitis or urticaria). In the case of an allergy, the best strategy is to reduce exposure to the responsible allergens as much as possible. Medications or other treatments may be needed to relieve symptoms and manage asthma.

Causes

Allergies occur when the immune system produces an excessive reaction against a foreign substance that is wrongly perceived as harmful even if it is harmless to the body. Animal allergens are a series of protein components that, if inhaled or placed in contact with the skin of particularly susceptible people, can trigger an allergic reaction of hypersensitivity.

After exposure to the allergen, the immune system reacts by inducing an inflammatory process, which manifests itself with the irritation of the upper airways and causes the typical symptoms of allergic rhinitis. Prolonged or regular exposure to the responsible allergen can cause an evolution of the allergic form into a chronic inflammation associated with asthma. Any animal with fur can be a source of allergens, but allergies are often associated with cats and dogs.

Allergy to cats and dogs

Dog and cat allergens are mainly produced by the sebaceous and salivary glands and accumulate on the animal's skin. The most important allergic components are found in the hair and flakes of dead skin (dandruff), as well as being present in their saliva, with which they clean the coat, in urine, faeces, tear fluid, sebum and sweat. Dandruff is a particular problem, because it is made up of very small particles and can spread in the air even for long periods of time. Furthermore, it is easily collected from upholstered furniture and clothes. Saliva can be attached to carpets, bed linen, furniture and clothing and, once dry, it can be dispersed in very small particles that can cause allergic symptoms when inhaled in the upper respiratory tract (nose and paranasal sinuses) or in the lungs.

  • The cat's main allergen is Fel d1, a protein molecule found mainly in dandruff, saliva, sebum, sweat and tear fluid. Cats often lick themselves and, given that the main source of allergens is found precisely in the sebaceous glands, this operation helps to deposit and spread the substances responsible for allergy. Cat allergens are one of the most important causes of respiratory allergy: they constitute a persistent aerosol that spreads to all parts of the house and seem to cause a predisposition to asthma. In particular, Fel d1, like other airborne allergens, is a component of dust and, therefore, it is extremely difficult to avoid exposure. The allergenic particles persist in the domestic environment even after 6 months from the removal of the animal (up to a maximum of four years). Furthermore, it must be taken into account that these are very light and small: for this reason the allergenic components are easily transported over large distances, as well as being able to penetrate deeply into the respiratory tree. Curiously, the cat's allergen was also detected in Antarctica, where felines were never present. All breeds of cats can potentially cause allergy. Furthermore, cross reactions can occur with dogs, horses and pigs or with other cats.
  • Dog allergy manifests itself less violently than the reaction triggered by cats and the allergenic load can vary between the different breeds. The main source of allergens is represented by saliva, urine, sweat and desquamation products of the animal. Can f1e Can f2 allergens contaminate the hair, causing as a result of their dispersion in the air, manifestations such as rhinitis, conjunctivitis, asthma, urticaria and edema. The dog's allergenic particles are heavier than those of felines and, therefore, spread to a lesser extent. In the subject susceptible to Can f1 and Can f2 cross-reactions can occur with cat and horse.

Allergy to rodents and rabbits

The rodents that make them more susceptible to allergic reactions are mice, gerbils, hamsters and guinea pigs. Allergens from rodents are usually found in hair, saliva and urine. The dust contained in the litter or in the sawdust on the bottom of the cages can help spread the allergens present in the air. Instead, urine contains the characteristic allergen of hamsters and mice. The spread of these protein components on clothes or other objects may be sufficient to trigger allergic rhinitis and asthma. Rabbit allergens, on the other hand, are present in hair and saliva, and represent a problem that particularly affects breeders.

Allergy to other animals

In the case of birds, allergies are caused by excrement, mites, pollen and substances deposited on feathers. The horse is able to trigger a severe hypersensitivity reaction, as it has very powerful allergens. Fortunately, close contact with the animal is necessary.

Allergy is rarely caused by animals that do not have fur, such as fish and reptiles.

Risk factors

Pet allergies are now common in the population. However, it is more likely to develop this disorder when there is a family predisposition to allergy or asthma. Early exposure to pets can have an impact on the risk of developing allergies: some studies have found that contact between infants and children during childhood sensitizes the immune system, limiting allergic reactions.