Most research on pet allergies has centered on allergies to cats, maybe this is no surprise because they are twice as likely to make their owners sneeze as dogs. Longer haired cats tend to shed less allergen and consequently owners with allergies have fewer reactions. Cats that are short haired traditionally give off more allergen, it is not known if this is true for dogs. It is recommended that dogs should be kept outdoors at night. Dogs and cats that live indoors should not spend any time in the allergic person's bedroom and never allowed on beds.
Dander collects in the carpets.
Bedding should be encased in plastic and if it is impossible to remove carpets then these should be steamed cleaned every three months to remove allergens. It is also advisable to wash walls and floors. Animal allergens are very small and very sticky and once they are secreted they dry on the animals fur, become stuck on fur and become airborne during petting and grooming. About 7 years ago I gave up smoking and noticed that I was coughing and choking when handling dogs. I wash my hands more than a surgeon and change my clothes about three times a day and wash my dogs every week.