Pet allergies is one of the most common allergic conditions caused by intolerance to antigens of wool, feathers, skin particles or pet waste products. The symptoms depend on the ways the allergen enters the body – itching, lacrimation, nasal congestion, sneezing, sore throat are most often registered. The pathology is determined by studying the patient’s life history, specific diagnosis is carried out using allergological tests. During treatment, contact with the source of the allergen is excluded, antihistamines and desensitizing therapy are prescribed.
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Intolerance or pet allergies is a common condition, in recent years there have been more and more cases of the disease. This is due to the improvement of diagnostic methods and an increase in the number of pets in general – according to statistics, cats, dogs or other animals are kept by 30 to 80% of families. Most often, an allergic condition is registered in children, the disease can occur at any age and suddenly disappear after a certain period of time. According to some data, at least 15% of the total population of the Earth are susceptible to the development of pathology. A small proportion of cases are represented by persons involved in agricultural work – caring for cows, goats, poultry. Epidemiology reflects the prevalence of contact with allergens – the incidence is higher in countries where more people keep pets.
The etiology of allergy is similar to other allergic conditions with contact or air transmission of a provoking substance (for example, pollinosis). For one reason or another, the patient has a perverted immunological reaction in response to the penetration of foreign substances of a protein nature. In this pathology, the source of such compounds are domestic or, less often, farm animals. Due to frequent and close contact with pets, allergies to them are characterized by a long chronic course, may be complicated by other immunological conditions. Provoking antigens may be contained in secretions:
- Elements of the cover. Particles of wool, scales of skin or feathers most often contain substances in their composition that cause allergic manifestations. Having a small size and light weight, they are able to stay in the air for a long time, penetrate the respiratory tract. Fluff and wool can also be fixed in the fabrics and pile of carpets – this explains the persistence of allergies even after eliminating communication with the animal.
- Exoparasites. Sometimes allergens are found in organisms that parasitize animal integuments (fleas, microscopic mites). Often this type of pathology occurs suddenly and disappears after the treatment of the animal.
- Waste products. Feces or urine of some animal species may contain provoking substances. Most often, allergies manifest themselves after cleaning trays, cages or terrariums and are limited to skin symptoms. Sometimes the appearance of allergens in secretions is associated with diseases of pets.
Various substances included in shampoos, veterinary drugs, cell cleaners can also provoke the occurrence of allergic symptoms. This variant of the pathological condition may be misdiagnosed as an pet allergies. Factors predisposing to the development of the disease are the presence of immunological disorders, other allergic conditions (for example, bronchial asthma), childhood age. Violation of animal care contributes to the occurrence of pathology – the accumulation of potential allergens in large quantities can cause a reaction even in a healthy person. At the same time, contact with animals in early childhood (less than 2 years) reduce the risks of allergies in the future due to the development of immunological tolerance to certain antigens.
Despite the variety of clinical manifestations, the reaction to allergens of domestic animals proceeds along the same pathogenetic pathway – hypersensitivity reactions of the immediate type. At the first contact with the antigens of animal integuments, their parasites or secretions, the organism is sensitized. Provoking substances are recognized by the immune system, class E (IgE) antibodies are formed against them. Immunoglobulins are absorbed on the membrane surface of tissue basophils (mastocytes), making them susceptible to allergens. These cells play a central role in the further development of the pathological condition.
During subsequent contacts, allergens bind to IgE located on basophil membranes. This activates these immunocompetent cells and stimulates the process of their degranulation – the release of histamine, serotonin and prostaglandins into the intercellular space. These compounds contribute to the expansion of blood vessels and increase the volume of intercellular fluid, irritate sensitive nerve endings. This is manifested by typical pet allergy symptoms – redness, swelling of tissues, itching, unpleasant sensations, increased exudation of mucus or tear fluid. Sometimes the amount of histamine released is so large that it leads to systemic reactions (anaphylactic shock) – a sharp drop in blood pressure, spasm of the respiratory tract.
Symptoms of animal allergy
The manifestations of pet allergy are quite diverse, largely determined by the type of intolerance, the nature of the allergen and its distribution in the patient’s environment. In most cases, pet antigens spread through the air, easily penetrate into the upper respiratory tract and the conjunctiva of the eyes. There is nasal congestion, lacrimation, sneezing, redness and itching of the eyes. Often these manifestations are joined by headaches, unpleasant sensations in the throat, sometimes hoarseness of the voice appears. Asthma patients may have bronchospasm attacks 20-30 minutes after inhaling air containing allergens.
In some patients, skin manifestations due to direct contact with animals or products of their vital activity come to the fore. As a rule, urticaria is detected in the area of contact of the skin with the provoking substance, sometimes it develops on other parts of the body. The duration of preservation of erythema, itching and other symptoms depends on the reactivity of the body and the amount of allergens in the environment. Often there is a combined development of ocular, respiratory and skin allergic manifestations. Some of them can occur in the form of contact dermatitis through a delayed hypersensitivity reaction (HSR), which is more often observed in people caring for farm animals or zookeepers.
In patients with severe sensitization to animal antigens, allergic symptoms may develop even in the absence of direct contact. The main and most common allergens of cats (Fel d1 and Fel d2) and dogs (Can f1 and Can f2) can be transferred through clothing and other items of the owners. For highly sensitized individuals, such indirect contact is sufficient for the development of a characteristic pet allergies symptom complex. The possibility of indirect interaction with provoking compounds is important to consider when diagnosing pathology.
Serious complications for this allergic condition are uncharacteristic, but the risk of their occurrence increases if the symptoms of the disease are ignored and contact with allergens continues. In people with bronchial asthma, the reaction can lead to severe bronchospasm and insufficient respiratory function. Allergic nasoconjunctival syndrome can be complicated by secondary bacterial infection of the mucous membranes, provoking purulent-inflammatory rhinitis or conjunctivitis. In extremely rare cases, anaphylactic shock develops upon contact with animal antigens, which is a life-threatening condition. A long course of allergic rhinitis can provoke hyperplasia of the nasal mucosa and the appearance of polyps.
The identification of this condition in practical allergology requires a comparison of a large number of anamnestic, clinical and laboratory data. This makes it possible to establish the relationship between the presence of a pet and the occurrence of pathological manifestations, and laboratory techniques make it possible to confirm and clarify the diagnosis. Diagnosis can be difficult, since some patients have a symptom complex that occurs some time after a cat or dog has appeared in the house. Allergy diagnosis is performed according to the following algorithm:
- Survey and general inspection. On examination, characteristic nonspecific manifestations of allergy are revealed – urticaria, conjunctival redness, lacrimation, complication of nasal breathing. When questioned, the presence or absence of contact with animals during the last days and in previous periods is determined. When interviewing a patient, it is also possible to determine the relationship between symptoms and pets and thereby adjust the plan for further diagnostic measures.
- Laboratory techniques. The general blood test usually shows minimal changes – a slight increase in ESR, eosinophilia and other signs of allergic inflammation. Specific tests reveal a significant increase in the level of type E immunoglobulins, which indicates an anaphylactic type of intolerance reaction.
- Allergological tests. The gold standard for the diagnosis of animal allergies are skin allergological tests – application, PRICK test. Usually, the body’s reaction to common allergens of dogs, cats, birds is determined (depending on which animal the patient contacts).
Differential diagnosis of pet allergies is performed with other types of allergic diseases (for example, pollinosis, intolerance to household dust), inflammatory pathologies of the mucous membranes (rhinitis, conjunctivitis). The distinction of these conditions often becomes possible only after conducting provocative allergological tests, which are a method of specific diagnosis.
Treatment of animal allergies
The issue of pet allergies treatment is often complicated by the unwillingness of patients to isolate the source of their pathological condition – a pet. In some cases, this leads to cooperation between an allergist and a veterinarian, together specialists can determine the nature of the allergen and find out how to reduce its release to animals. Such measures are effective in case of intolerance to the components of care products (shampoos, sprays), exoparasites or animal secretions – it is enough to cure the pet and minimize contact with excrement (cleaning trays). In addition to eliminating contact with provoking antigens , the following therapeutic measures are distinguished:
- Antihistamine therapy. Antihistamines are widely used to reduce allergy symptoms. They can be prescribed in the form of tablets, eye or nasal drops and sprays during the period of exacerbation of the disease or as a preventive measure – for example, before alleged contact with an animal.
- Desensitizing therapy. In relation to a number of animal allergens, it is possible to use specific immunotherapy (ASIT) associated with the development of tolerance to the provoking protein substance. The essence of the technique is reduced to the introduction of small, gradually increasing dosages of allergen for several months.
- Barrier techniques. Experimental methods based on the formation of the thinnest film based on cellulose or other compounds in nasal drops in the nasal mucosa. As a result, the entry of allergens into the tissues becomes more complicated, the manifestations of allergies decrease. The techniques do not protect the skin or conjunctiva of the eyes, so they are used with a limited list of indications.
After diagnosis of pet allergies, in addition to excluding contact with a pet, thorough cleaning of residential premises is necessary. Wet cleaning of floors, walls, furniture is carried out, carpets, upholstery and other fabric elements of the interior are carefully knocked out. It is recommended to install filters for air purification for a while, since the smallest scales of skin and down can remain suspended even in the absence of dogs or cats.
Prognosis and prevention
The prognosis of pet allergies is almost always favorable, only in people with a tendency to bronchial asthma it worsens due to the risks of bronchospasm. Often, the manifestations of the disease become less pronounced over time, even without serious therapeutic measures, so some patients prefer not to part with a pet, easing allergy symptoms with antihistamines or agreeing to ASIT. Preventive measures help to reduce the concentration of animal allergens, reduce both the risk of occurrence and the severity of pathology. These include careful care of the animal, the use of household air purifiers, washing hands after stroking or playing with a pet. It is important not to allow the animal on chairs or beds, especially in the bedroom, when traveling in the car, use special seat covers.