|Year : 2014 | Volume
| Issue : 1 | Page : 47-48
Successful allergen immunotherapy with horse dander allergy
S. N. Gaur, Gaurav Bhati
Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, New Delhi, India
|Date of Web Publication||11-Jun-2014|
S. N. Gaur
Department of Pulmonary Medicine, Vallabhbhai Patel Chest Institute, University of Delhi, New Delhi - 110 007
Source of Support: None, Conflict of Interest: None
Allergic disease induced by animal exposure is a well-known fact. Exposure to dander of pets such as cats and dogs can lead to allergic manifestations of allergic rhinitis, allergic asthma, and contact urticaria is a well-recognized fact. Allergy to horses can also present with all these symptoms as well as anaphylaxis in the subjects who are previously sensitized. Horse allergy is induced by exposure to the major horse allergens Equ 1 through five with the level of exposure determining the level of severity. Greatest risk of anaphylaxis occurs in those sensitized patients who have large amounts of animal allergen exposure, with maximum chances with animal bite as it exposes the sensitized persons to large quantities of the animal allergen that resides in the saliva. Horse allergy may be successfully treated with allergen specific immunotherapy.
Keywords: Allergen immunotherapy, anaphylaxis, horse dander
|How to cite this article:|
Gaur SN, Bhati G. Successful allergen immunotherapy with horse dander allergy. Indian J Allergy Asthma Immunol 2014;28:47-8
|How to cite this URL:|
Gaur SN, Bhati G. Successful allergen immunotherapy with horse dander allergy. Indian J Allergy Asthma Immunol [serial online] 2014 [cited 2019 Sep 17];28:47-8. Available from: http://www.ijaai.in/text.asp?2014/28/1/47/134225
| Introduction|| |
Allergic diseases caused by animals are not uncommon. Allergy to pets, such as cats and dogs, horses can lead to significant morbidities in children. Allergies to pets can manifest as asthma, urticaria, angioedema, contact dermatitis and anaphylaxis. At many places in developing countries horses are still used for various works, including transportation whereas in developed countries, horses are widely owned and used for recreational activities. Horses have been recognized as an important source of allergens for people who regularly work with horses, either professionally or for recreational purposes. Despite the presence of horses in a variety of recreational, sporting, and work environments, there are only a few reports of anaphylactic episodes resulting from horse allergy.
| Case report|| |
An 18-year-old boy, presented with episodes of acute breathlessness, wheeze and nasal symptoms, within 10 min of coming in contact with horses. Prior to presentation at our institute, the boy had an episode of nausea, vomiting, diarrhea and breathlessness, followed by drowsiness during horse riding. During the present episode on examination he had pulse rate of 110/min, blood pressure 80/50 mm Hg and an axillary temperature of 36.3°C. Lung auscultation revealed wheeze throughout all lung fields. He was diagnosed to be in anaphylaxis and was treated with subcutaneous injection adrenaline (1:1000), intravenous hydrocortisone, antihistamines, and physiological saline. The patient recovered and was subsequently discharged 24 h later. After recovered fully from systemic reactions, he was brought at Department of Pulmonary Medicine, University of Delhi, Delhi (India).
The detailed history of a patient revealed several such as episodes of anaphylaxis and hospital admissions on coming in contact with horse in the past as well, out of which three episodes were within a span of 3 months. The skin prick test was done, which tested strongly positive +++ only with horse dander allergen. It was done using different concentrations (0.001, 0.01 and 0.1 μg/ml) of horse dander allergen supplied by All Cure Pharma. He was then started with subcutaneous specific allergen immunotherapy (SCIT). Even on treatment the boy faced mild symptoms during the 1 st year. After being given the immunotherapy in the maintenance dose for 1.5 years (up to 2004), he never had anaphylaxis even on coming in contact or riding the horses until now although he discontinued SCIT after 1.5 years on his own due to sufficient improvement.
| Discussion|| |
Horses are known from the ancient times to be the animal of use for daily purposes and work. In the modern world, horses are being used for recreational purposes. Allergic manifestations such as asthma and anaphylaxis has been connected with a number of animals, including cats, dogs, rats, mice, cows, and horses.  A correlation between the exposure of farm animals at early childhood and allergic manifestation has been made by various studies done in Europe. The studies indicate that early exposure to farm animals leads to a protective effect against animal induced allergy and asthma. ,, also exposure to animals at homes during the 1 st year of life has a similar protective effect, by development of immune response by immunoglobulin (IgG) directed against animal dander. 
Horses have also proven to be one of the important and significant allergen sources among all the mammalian allergens. Horse dander, hair, and skin scrapings can lead to manifestations of allergic response. In 1950s, the first allergic reactions to horse serum on therapeutic injection were described and thus horse serum albumin was reported as the first known horse allergen.  In the 1970s, various dander derived allergens were described, which were designated as Ag 6, Ag 9, and Ag 11. Subjects with allergy to horses were found to have specific IgE against these antigens.  Horse allergens are mainly protein in nature with molecular mass ranging between 10 kDa and 75 kDa. 
Horse allergens are of four types that have been purified to homogenicity until date namely Equ c1, Equ c2, Equ c3 and Equ c4. Equ c1 is a major hair dandruff protein synthesized in liver and in the sublingual and submaxillary salivary glands whereas Equ c2 and Equ c3 were isolated from horse sweat. Purification of Equ c4 has led to a new allergen from horse dander named as Equ c5 which has now been identified and characterized. 
Horse allergy occurring among handlers of horses is mainly characterized by rhinitis, conjunctivitis, asthma, urticaria and at times anaphylaxis. Although allergen avoidance has been crucial for management of allergic manifestations, pharmacotherapy with injectable epinephrine, oral antihistamine for the management of the anaphylaxis is recommended. A proper diagnosis of horse allergy can be made based on skin prick test, which is both simple and inexpensive. Allergen immunotherapy may be the treatment of choice in cases of animal allergy in cases where allergen avoidance is not possible.  Allergen immunotherapy against horse allergy has been proved both safe and efficacious in patients with allergic symptoms of asthma and rhino-conjuctivitis with or without cutaneous symptoms. 
In this case, the boy tested strongly positive +++ for horse dander and had anaphylactic reactions in the past as well.
| Conclusion|| |
It is concluded that physicians should be aware of the anaphylactic reaction due to exposure to horse dander and specific allergen immunotherapy with horse dander (whole body extract) is effective and lifesaving.
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