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Human Allergies and the Portuguese Water Dog
by David E. Smith, MD

Are PWDs "Hypoallergenic"?

Over the more than two decades that we have bred both poodles and Portuguese Water Dogs we have been asked many times if these dogs are "hypoallergenic". The question is important, as it has been estimated that nearly 5% of the U.S. population have varying degrees of allergies to dogs. The term "hypoallergenic" is a created word and was coined in an advertising campaign for an Almay cosmetic product in the 1950s. The derivation of the word is the Greek "hypo" meaning "below normal or less than" and was used to describe cosmetics that produced fewer than normal allergic skin reactions in individuals with sensitive skin. The FDA tried to define the term "hypoallergenic" by requiring the cosmetic industry to provide evidence that a product with this label caused less allergic complaints. Two cosmetic firms Almay and Clinique that used the term extensively in their advertising sued the FDA and the US Court of Appeals overturned the proposed FDA regulation in 1977. Therefore there is no medical definition or criteria for the term "hypoallergenic". It is commonly used to mean a lower level of allergens or less allergy causing. We must emphasize that there is no such thing as a non-allergenic dog. (All dogs shed skin cells (dander), lick (saliva) and urinate (urine) which are the prime sources of canine allergens.) The Portuguese Water Dog (PWD) is one of thirteen breeds listed by the American Kennel Club as being hypoallergenic although the term allergy friendly is more appropriate. Two of the thirteen are basically hairless: the Chinese Crested and the Xoloitzcuintli. The other eleven including the PWD are basically nonshedding and have little dander. In nearly every litter that we have bred over the years one or two puppies go to homes with a history of allergies to dogs and we have had only one puppy returned in nearly 20 years of breeding PWDs confirming that the breed has a lessened chance of causing an allergic reaction.

Canine Allergens

Recent studies have demonstrated that Canis familiaris allergen 1 (Can f 1) is the major allergen that causes human allergic reactions. Can f 1 is secreted by tongue epithelial tissue. Can f 2 is secreted by the parotid gland and is considered a minor canine allergen. Both are present in large quantities in saliva and to a lesser degree in urine. Both allergens are small lipocalin proteins which act as ligands when bound to human protein receptors and trigger intense human allergic reactions. Canine albumin also found in saliva and urine can be an allergen in a minority of cases. A recent study has shown that levels of Can f 1 vary widely between breeds and this may explain why some breeds are less allergic (hypoallergenic). The sebaceous glands of all dogs produce some level of Can f 1 and Can f 2. The greater degree of sebaceous gland secretion that we call seborrhea increases the level of Can f 1 found in canine fur. Dried sebaceous gland secretions together with dead skin cells are called dander and contain large amounts of these allergens. This dander becomes attached to fur that is shed into the environment and this explains why breeds that shed are much more allergenic. Dogs that shed their skin cells frequently are also thought to be more allergic than breeds such as PWDs who shed their skin cells less frequently.

Paradoxical Reduction of Childhood Asthma

Several large recent prospective birth cohort studies have clearly shown that a home with a dog reduces the incidence of childhood asthma if the child is exposed to the dog early in life (less than 1 year of age). The more pets in the household the greater the protection. The most striking observation is that the protection is greatest in families with a strong family history of asthma. This would seem paradoxical since children with asthma worsen with exposure to pets. This protective effect appears to be related to the fact that all dogs and cats for that matter shed endotoxin from Gram-negative bacteria. This may explain why rural children have such a low incidence of asthma since farm animals shed massive amounts of endotoxin. The old belief that "country air was better for asthma" might be caused partially by this finding although polluted urban air clearly plays a role in the high incidence of asthma in children living in large cities. The one takeaway from these studies is that if a young couple with a family history of asthma is planning on starting a family. They may want to bring an allergy-friendly dog breed into the household may lessen the chances of their children developing asthma.

Testing for Allergens

Most allergists rely on some type of testing to sort out the allergens that any individual may be sensitive to. Usually skin prick testing to a wide gamut of potential allergens is used in initial screening. It has been used in diagnosing human allergies for more than a hundred years. Intradermal allergen injection may be done but tends to overestimate the degree of allergic potential to an allergen. Blood tests may be required using ELISA or RAST (food allergies) methodology if the individual cannot be taken off of medications such as antihistamines that might alter the results of skin testing. Blood testing is almost always used to confirm the allergen in an individual who has had an anaphylactic reaction. The recent wide availability of pet allergens produced by recombinant technology allows precise testing for Can f 1, Can f 2, and Fel d 1 (cat allergen). Almost all individuals who are allergic to dogs will have additional environmental allergies and this frequently complicates treatment decisions.

Mechanism of Allergic Response

The human immune system has evolved to defend us against various threats. The Immunoglobulin E system (IgE) is our protection against parasites and when they attack us the human body mounts a tremendous IgE response. "Allergic" or "atopic" individuals generate a similar exaggerated response to nonparasitic allergens. This is medically termed a "Type I Hypersensitivity Reaction". The three most common human environmental allergens that can induce this IgE response are dust, pollen, and pet dander. Less common allergens are certain foods, molds, medications, plants and insect bites. IgE mediated reactions to allergens range from mild such as hives and sneezing, moderate such as wheezing (bronchospasm), or severe such as anaphylaxis. Individuals with severe allergic reactions to dogs that have required aggressive medical treatment should never consider adopting a dog.

Coat Type

Over the years we have found that wavy or loose curly dogs are best for families who have allergies. A tight curly coat tends to trap environmental allergens such as pollens and seeds and brings them inside the home and this can exacerbate other allergies. We have placed tight curly puppies in homes with allergies and they seem to work out well but our preference is a wavy or loose curly coat. INCORRECT COATS ARE NOT NONSHEDDING AS THEY ARE ALMOST ALWAYS DOUBLE-COATED AND DO TRIGGER ALLERGIES WHEN THE UNDERCOAT SHEDS.

Weekly Bathing

Bathing the PWD frequently reduces environmental allergens (dirt, pollen, other plant material, etc.) that can be trapped in the coat. It is extremely important to use a shampoo made for dogs. These shampoos are alkaline and usually have a pH of 7.5 while human shampoos are acidic with a pH close to 6.0. If you use an acidic (human) shampoo on a PWD you will irritate the alkaline skin of the dog and this will cause the PWD to itch and scratch. Scratching causes more irritation, scaling and excessive shedding of both skin cells and hair. It is very important to rinse all the soap off the dog, as it can be irritating. Canine hair conditioners or topical products such as Allerpet-D™ may safely be left in the dog's coat.

General Measures

•Hand washing after playing with the dog is mandatory.
•Carpeting, drapery and upholstery trap allergens in the textile interstices and must be vacuumed with a closed vacuum system with HEPA filter frequently.
•Many allergists suggest removal of wall-to-wall carpeting and upholstered furniture to minimize trapping of airborne allergens (dander).
•Leather covered furniture is much easier to clean.
•HEPA (High Efficiency Particulate Air) room air filtration systems are mandatory in the rooms that the dog lives in.
•Use of impervious mattress and pillow covers with weekly hot water washing of all bedding reduces canine allergens in the bedroom.
•Keeping the dog out of the bedroom of the allergic individual or at least off the bed is crucial.
•The dog's bedding and particularly his/hers soft toys which are coated with saliva should be washed in hot water twice a week. Use an anti-allergenic detergent such as Nature's Miracle® Anti-Allergen Deodorizing Detergent, Allersearch® AllergenWash™, or AllerTech® Laundry Detergent to wash all bedding and toys.

The Acid Test

My interest in allergies and the PWD has caused me to question my allergist colleagues on how to test for whether a PWD puppy will trigger an allergic response. Over the years tee shirt/pillow case blind testing has been popular particularly with rare breeds that may not be available locally. This requires the allergic individual to ship labeled paired tee shirts or pillow cases in separate labeled Ziploc™bags to the breeder who then allows one of her dogs to sleep on one of the items. The other item is kept sealed in it's bag. The paired items are returned in the sealed bags. The allergic individual then alternate wearing the tee shirts or sleeping on the pillowcases and notes any response. The test is done blinded and only the breeder knows which of the two items has been in contact with a dog. This may be a useful screening test but I feel the best test is to place the allergic individual in close proximity to the puppy for 25-30 minutes. This is best done in a controlled environment with as few other potential allergens as possible. I recommend a freshly detailed automobile with the air system on recirculation as the control environment thus limiting other external allergens.


David E. Smith, MD

Created September 2008
Modified May 26, 2009