Hypersensitivity dermatitis in cats

Hypersensitivity dermatitis (HD) in cats has been much less studied than in dogs. The use of the term “feline atopic dermatitis” is questionable because this syndrome has not yet been well characterized in its clinical manifestation. Furthermore, the importance of IgE in the pathogenesis of hypersensitivity dermatitis in cats has not yet been demonstrated. The allergen-specific IgE levels are not specifically correlated to the clinical manifestations of HD and a high percentage of cats with HD are reported with negative results in all IgE tests.

Clinical symptoms and diagnosis of hypersensitivity dermatitis

Since HD manifests itself with a great variety of clinical symptoms, an accurate and thorough diagnostic process is necessary. The diagnosis of HD in cats should be based on the exclusion of other itchy diseases caused by adverse reactions to food, ectoparasites, fungal and bacterial infections, viral infections, psychogenic alopecia, autoimmune diseases (eg. Pemphigus) and tumors.
A genetic predisposition is hypothesized and it has been shown that females are more subject to non-flea HD, while males appear to be more subject. In most cats, the onset of symptoms occurs between 6 months and 3 years of age.
In most cases, the clinical manifestations of non-flea HD are: pruritus with excoriations on the head, muzzle, neck (which can then extend to the abdomen and tail), self-induced symmetrical alopecia, manifestations of the eosinophilic granuloma complex (plaque or eosinophilic granuloma, indolent ulcer) or miliary dermatitis.
The cat with flea-induced HD has itching and lesions in the dorsal-lumbar region, tail, head and neck.
The cat with HD induced by adverse food reactions has more frequent itching and lesions on the head, muzzle and neck; moreover, it can present gastrointestinal symptoms.
In conclusion, it is noted that the itching and head and neck lesions described above are common in most cases and therefore cannot be considered specific for the diagnosis of HD.
Symptoms such as: asthma, rhinitis and blepharo-conjunctivitis may also be present, although in a small number of cases.
The diagnostic process must therefore include the exclusion and possible treatment of dermatophytes, bacterial infections, ectoparasites (Cheyletiella, Otodectes, Notoedres), fleas, adverse food reactions, autoimmune diseases (eg. Pemphigus) and psychogenic disorders.

It can be considered, with a good probability, that cats suffer from non-flea HD if at least 5 of the following 8 criteria are present (Favrot et al.):

  • at least two parts of the body involved,
  • symmetrical alopecia,
  • at least two of the following clinical pictures: symmetrical alopecia, miliary dermatitis, head and neck erosions, eosinophilic dermatitis,
  • any lesions on the lips,
  • erosions and ulcerations of the chin and neck,
  • absence of lesions on the back,
  • absence of non-symmetrical alopecia on the back and tail,
  • absence of nodules and tumors.

The “allergy” tests

It is important to remember that the serological test for the detection of IgE cannot be used for the diagnosis of feline HD. The serological test may not be diagnostic in case of negativity. Therefore, the results must always be evaluated and interpreted in the light of the animal’s clinical and environmental history.

The analysis service for cats

Il Servizio analisi

The analysis service for the research of specific allergen IgE in cats is reserved exclusively for veterinarians.
Requests for analysis will be processed within 72 hours from sample receipt, and the results will be sent by e-mail, post or fax to the requesting veterinarian.
It is advisable to forward to the laboratory, together with the sample, the request for analysis together with the patient’s medical history. It is possible to download the anamnestic form by selecting: Download anamnestic form
The service is reserved exclusively for Veterinarians. Requests from private individuals will not be accepted.

List of exams

Semiquantitative research test of allergen-specific IgE on:

  • Prescreening panel
  • Pollen panel
  • Environmental panel
  • Food panel

The panels can be requested individually or in combination.
The prescreening test, based on the ELISA technique, allows to evaluate the presence of allergen-specific IgE in the sample against groups of allergens (pollen, mites). This test can be useful to highlight the possible presence of specific allergen IgE and to indicate to which panel the in-depth serological investigation can be directed.
The different specific panels measure the levels of IgE towards individual allergens and are characterized by a high territorial significance.
The Agrolabo Research Center currently collaborates with Stallergens Greer (USA) using the macELISA method (mac = cocktail of monoclonal antibodies) in a system specifically designed and customized for Italy.
The test uses 3 monoclonal antibodies that distinguish 3 different epitopes of the FC region of IgE. This methodology, thanks to its binding specificity, eliminates the possibility of false positives due to interference with IgG and, thanks to the well-known quality of the Greer allergenic extracts, increases the specificity of the results. Therefore, this assay offers reliable, repeatable and comparable results to those of the high affinity receptor-based ELISA technique.

Quality Control

The Agrolabo analysis laboratory voluntarily participates in a standardization and inter/intralaboratory quality control program established by Stallergens Greer at an international level with other important European and American laboratories, thus ensuring an accurate, reproducible and reliable service.

Sample

To carry out the research analysis of specific allergen IgE in cats, a serum sample with a volume of 1 ml is required.
The sample is properly stored for 6 months after receipt in Agrolabo laboratory.

Do steroids affect the test?

Corticosteroid treatments do not appear to affect the serological test results. If possible, suspend the treatment with corticosteroids for at least 7-14 days if the duration of administration is not prolonged and/or given at high doses.

Age for analysis

It would be better to perform the tests for specific allergen IgE over 6 months of age. In case of a certain clinical diagnosis of atopy under this age, the analysis can be performed and in case of negative results it is better to repeat the analysis after 6 months.

Seasonality

While the season does not appear to affect the serological test results, the best time to test a serious pollen allergy sample is the end of the summer season.

Allergens

It is very important to emphasize that a positive test alone does not justify a diagnosis of atopic dermatitis, but is only indicative of the fact that the animal has IgE antibodies to the allergen tested.

Allergens are tiny particles present in the environment such as pollen, mold spores and mites capable of inducing a type I hypersensitivity reaction in a susceptible individual. Allergens are complex particles of which only some molecular components are allergenic, due to the presence of two or more antigenic determinants.
These are water-soluble proteins or glycoproteins with a molecular weight between 10 and 70 kD and with a size between 2 and 60 μm. To be a significant allergen, a particle must have antigenic properties, must be present in large quantities and must be easily dispersible.

Allergens are divided into three groups:

1) Allergens from herbaceous and tree pollen

The presence and quantity of pollen are strongly influenced by climate, humidity and vegetation because, being very volatile particles, they are subject to the effects of wind, rain, gravity and atmospheric pressure: the science that studies these factors takes the name of aerobiology. For diagnostic purposes, it should be emphasized that the pollens of anemophilous plants are much more important as they are produced in much higher quantities than the pollens of entomophilic plants and are smaller and more dispersible.
The pollens of grasses are among the most important, in consideration of the fact that they occupy 20% of the vegetation cover of the globe, have a great allergenic significance and (depending on the latitudes and climates) have different pollinations. Pollination in our regions takes place from April to September.
Since most grass pollen contains some antigens common to the whole family, most pollen are cross-reactive with each other. For this reason, in most of the tests these pollens are divided into groups of the same subfamily or that share common antigenic groups and, within 70% of cases, a positive result is found for all groups.
The pollens of “weeds” include different botanical families and are herbaceous species present everywhere in large quantities. Among the composite, particular attention deserves Ambrosia, a plant native to America where it is considered one of the most powerful allergens and which is colonizing all of Europe with a particular predilection for the southern, coastal and lowland regions. Ambrosia seems to be the only allergen responsible for respiratory problems and allergic rhinitis and conjunctivitis.
The pollens of tree plants deserve a separate consideration: since these plants are normally characterized by only one annual pollination (some species even every two years) and it is normally in a specific period of the year, the positivity to these allergens must be carefully evaluated, depending on the therapies.

2) Environmental allergens

Mites: they are important allergens present in domestic environments in favorable conditions of high temperatures and humidity.
They include dust mites: Dermatophagoides farinae and D. pteronyssinus and food mites: Acarus siro and Tyrophagus putrescentiae and Lepidoglyphus destructor.

Mites of the genus Dermatophagoides are present on mattresses, carpets, padding of sofas and chairs rather than in the “dust” of the floors. They are characterized by two specific allergens, one contained in the faeces and one somatic present in both live and dead insects, therefore treatments with acaricidal products can decrease the presence of mites but not decrease the allergenic load.

Food mites: Acarus siro (flour mite), Tyrophagus putrescentiae (ham mite) and Lepidoglyphus destructor (mill mite) prefer particular environments (silos, food warehouses, granaries, barns) and can be easily transported with packaging generally arriving then in homes. In the event of adverse environmental conditions, they can enter a stage of quiescence and the return of conditions favorable to their development can lead to demographic explosions, thus increasing the allergenic load. Food mite allergens can be cross reactive with dust mite allergens.

3) Food allergens

Food allergens are mostly large glycoproteins. Normally the digestion of proteins breaks the bonds forming peptides and amino acids that are not allergenic. As a result, poorly digestible or heat-stable proteins can become allergenic.

From literature and analytical experience, the most common allergens in cats are beef, milk and dairy products, wheat, soy and to a lesser extent lamb and chicken.

There may be cross-reactivity with other food allergens (beef with milk) and with aeroallergens and multiple sensitivities are common.

For requests and further information, contact the Agrolabo marketing office:
Phone: 800-805076  |  +39 0125 731111  |  allergia@agrolabo.it