Allergic reactions to the domestic dog (Canis familaris) give rise to symptoms such as conjunctivitis, rhinitis, and asthma. Dogs secrete various proteins that end up in their saliva, urine, and dander (dead skin) – the most pertinent one being dog allergen known as Can f 1.
Several steps can be taken by dog owners to reduce allergens and to tackle this problem. Proper management includes the avoidance of allergens (where possible), the usage of topical or systemic medications, immunotherapy, and the treatment of any concurrent conditions.
Complete avoidance or removing the dog is the best way to approach the problem of dog allergy, although it is often neither feasible nor wanted. Therefore, other strategies to reduce symptoms are often used – one of them is restricting the dog’s access and movement to only a couple of rooms (and definitely keeping the dog out of the bedroom). This will not preserve the allergens only in that room, but will drastically reduce their burden in the air.
Furthermore, it is not advisable to hug, pet, or kiss the dog in cases of allergic reactions. If these actions are pursued anyway, then the hands should be thoroughly washed with soap and water. Bathing the dog at least once every week can also significantly reduce dog allergen content in the air.
High-efficiency particulate air portable room air cleaners (HEPA PRAC) are a viable option for combating dog allergies, as they can run uninterrupted in a bedroom or other parts of the house, successfully reducing allergen levels over time. Research has also shown that the use of cyclonic HEPA vacuums two times a week can improve asthma outcomes.
Similarly, studies have shown that castration of dogs is clearly associated with lower levels of dog allergens in the air, albeit floor dust levels are not influenced. Castration is also associated with lower levels of Can f 1 in hair, but there is no difference in shedding (represented by coat levels) between castrated and non-castrated animals.
Using drugs in asthmatic patients allergic to dogs necessitates a stepwise approach that follows clear asthma management guidelines. Short-acting beta-agonists and corticosteroids are still the mainstay of therapy; nevertheless, antihistamine use before anticipated exposure to dogs, intranasal steroids and leukotriene antagonists are considered to be an adjunctive therapy.
Allergen-specific immunotherapy represents the only curative option for the treatment of dog allergies. Immunotherapy of allergic patients is still based on conventional allergenic extracts, but these have been shown to vary significantly in terms of allergenic contents. Unlike the situation with cats, dog immunotherapy based on the use of natural extracts has quite modest clinical efficacy.
A majority of allergen-specific immunotherapy is extract based and contains allergens in a natural conformation. Still, this can result in natural inconsistency of extracts that can be dealt with by using recombinant techniques in order to develop suitable therapy combinations. Some of the approaches use hypoallergenic variants, mosaic multi-allergens, or simply a mix of allergens.
Genetic engineering can be employed to modify allergens and produce soluble and structurally stable recombinant allergen molecules. For example, multimeric allergen construct comprise a plethora of desirable features such as the ability to induce high concentration of specific dog-allergen blocking antibodies, as well as improved safety profile.
Reviewed by Susha Cheriyedath, MSc