Of course, chronic recurrent otitis may also indicate the presence of a food allergy. For this reason, the animal should undergo a rigorous elimination diet. However, dogs with atopic dermatitis also often develop otitis.
Symptoms: A dog has a very persistent chronic recurrent otitis that cannot be controlled with conventional otic therapy. Can this also be due to an allergic cause?
Symptoms: A dog clinically shows only respiratory symptoms. Can an allergic disease be the cause? Are there similar diseases to feline asthma in dogs?
Allergic reactions in dogs usually manifest themselves in the form of skin symptoms (itching, secondary efflorescences, secondary infections, especially in the head and extremities).
Reactions of the respiratory tract are rather rare, but do occur. These then manifest themselves with asthma-like symptoms or chronic bronchitis and/or rhinitis. In an acute asthma attack, the airways are suddenly narrowed and the bronchial muscles in the lungs contract like a spasm. The dog develops dyspnoea, which is obvious even to the owner. The reasons for asthma lie in a wide variety of stresses to which the body reacts with an overreaction of the bronchial tubes and/or an allergic reaction. There are two main types of asthma: allergic bronchial asthma and non-allergic asthma. In allergic asthma, insect bites, plant pollen or house dust mites, among other things, can trigger an attack (very similar to humans). In non-allergic asthma (which is more common), shortness of breath occurs as a result of a viral, bacterial or mycotic infection of the respiratory tract and/or as a result of stress or overexertion. Too cold or too dry air or bad air (cigarette smoke) can also cause asthma attacks.
An allergy test without the presence of clinical symptoms is mainly considered before buying or taking over a dog, e.g. from a shelter.
However, this makes no sense, because allergy is always a clinical diagnosis. The test is used to identify allergens for avoidance or allergen-specific immunotherapy. There are animals that are sensitised but never become clinically manifest.
No, this is similar to suspected parasites. Only a positive result (correlating with anamnesis and clinic) is conclusive. A negative test only means that there was no direct allergen contact before or at the time of testing (outside the allergy season) or that the animal may have been unknowingly pre-treated with corticosteroids.
No, but the diagnosis can be made clinically and parasitologically, as these mites are clearly visible as orange spots, especially on the paws, in the armpit area, etc. of the animals.
No, there is no such thing. The detection of demodicosis is carried out on the one hand by the well-tried positive deep skin scraping or, since recently, alternatively by the Demodex PCR examination (material: deep skin scraping).
Sarcoptes: How many weeks after infection can it be detected in the blood? How many months after overcoming the disease are antibodies still detectable?
The antibody level (IgG) only reaches a corresponding level from approx. 4 weeks post infection, so that the test is positive. This means that a test 1-2 weeks after the onset of itching may be too early and give a false negative result. As an alternative to antibody determination, Sarcoptes PCR is suitable in this case (marterial: large superficial skin scrapings).
The antibodies remain detectable in the blood for up to 6 months or even longer after the infection has been overcome. Therefore, during this period, it is not possible to distinguish in the case of a positive or questionable Sarcoptes detection whether it is a new infection or whether “old” antibodies were still detected. This implies that the Sarcoptes antibody test cannot be used for therapy control!
ASIT: Does it make sense to perform an ASIT with only one allergen if a patient reacts positively to only one mite (e.g. Dermatophagoides farinae)?
Yes, but this makes sense – as long as the result of the differentiation of the year-round allergens correlates with the anamnesis and clinic. If an allergy to food/storage mites is present, a change of food can possibly be considered, but this also does not provide a hundred percent guarantee. Since house dust mites are always and everywhere present and therefore cannot be avoided, an ASIT with only one allergen makes sense here.
We observe the following success rates of ASIT in dogs:
- Age < 1 year: 38 % success
- Age 1-2 years: 75 % success
- Age 3-5 years: 88 % success
- Age 6-8 years: 89 % success
- Age 9-10 years: 53 % success
- Age > 10 years: 44 % success
See next question for reasons for the influence of age.
In a very young dog (2-3 months old) with itching, a food allergy and various ectoparasites are usually the triggering causes for the skin symptoms. In contrast, the typical age of onset of atopic dermatitis is 6 months/ 1 year – 3 years.
It is therefore not recommended to hyposensitise a 6-month-old dog. The probability is high that, on the one hand, the food allergy has priority and, on the other hand, that – if atopic dermatitis should really already be present at 6 months – not all sensitisations could have developed yet, since the animal has not yet experienced the complete allergen spectrum of a whole year. Furthermore, animals <1 year of age are not yet immunocompetent; the allergy is not yet fully developed.
Therefore, therapy should only be started when the dog is >1 year old.
The success rate also decreases in older dogs (>10 years), as their immune system behaves differently than that of a middle-aged dog.
ASIT: Does prophylactic immunotherapy make sense if a dog shows no clinical symptoms but positive reactions in the allergy test?
No, if there are no symptoms, it makes little sense to carry out an allergy test or an ASIT. Allergy is a clinical diagnosis. A positive allergy test in this case only provides information about sensitisation. But sensitisation does not necessarily cause clinical symptoms and therefore the following applies: no clinic, no disease. A positive allergy test may mean that an animal is below the threshold, but it may also mean that it will never develop allergic symptoms – also very much depending on the environment in which the animal lives. It can be symptom-free in location A and have massive problems in location B due to the allergen composition of the environment. This is analogous to the T4 value: a low T4 value does not necessarily mean hypothyroidism.
ASIT: A dog has been on ASIT for years and is clinically almost symptom-free. Does it make sense to repeat the allergy test to see if it is possible to stop the therapy?
Since ASIT should be administered for life anyway, it makes no sense to repeat the test. No conclusion can be drawn about the success of ASIT based on a repeated allergy test.
It would only make sense to repeat the allergy test if a dog that has been receiving ASIT with year-round allergens for years has now also developed an additional seasonal skin problem (or vice versa). In this case, the seasonal allergens should be differentiated and, if necessary, added to the existing ASIT as a second therapeutic solution.
Retesting would also be recommended if an animal that initially responded well to ASIT suddenly becomes symptomatic again and no other cause is found. In this case, an allergy test can be performed to see if the allergen spectrum has changed. If necessary, a new ASIT solution with the new allergens should be used.
A second therapy solution may be necessary, for example, if a dog already receiving ASIT with year-round allergens also develops a seasonal skin problem.
How to proceed then depends on the case. Either a new ASIT is ordered with the new and the old allergens instead of the follow-up treatment of the old solution, but then as an initial solution.
Or the old ASIT is continued as usual and in parallel treated with a set of new allergens as initial solution (caution – this results in different treatment intervals).
If not too many allergens are involved (up to 8 allergens), one can then combine a set of follow-up solutions from the 2 follow-up solutions at a later time.
This is not recommended because the allergy is based on a genetic component or predisposition.
FAQ = frequently asked questions
ASIT = Allergen-specific immunotherapy (new) = Hyposensitisation (old)
RK = reaction class