Around that point, my allergist informed me I was allergic to cats and shouldn't be a vet. Well, I told him, too late. I still break out and have sneezing spells on contact with certain long-haired cats, some pit bulls and shar-peis. I no longer test positive according to the allergist, but cat allergies are not well understood. Some people think it's the dander people are allergic to. Some people think it's their saliva (so when they groom themselves, their saliva gets on their fur and that is what people are allergic to), others say it's their anal glands. My opinion; people are probably allergic to different components. Supposedly in California, they have created a genetically modified cat that is "hypoallergenic".
Hypoallergenic dog breeds have "hair" rather than fur. (Most dogs/cats have continual hair growth and shed continuously. Dogs with hair still shed, just like people with hair shed. This means there is also still a potential for allergy there like with pretty much everything in the world. An allergy is simply the body over-reacting to a stimulus, which could be just about anything.
You probably don't know that probably about 60% of the problems we see as veterinarians are in some way allergy related. Just like with people, dogs and cats can get all sorts of manifestations of allergies. In cats, it's typically stomach issues and skin issues, such as rashes, occasionally sneezing and runny eyes and in extreme forms, asthma or allergic bronchitis. In dogs, we see saliva-stained (red) itchy paws and ear infections. Occasionally they will sneeze or cough, but this is a lot less likely to be seen in the absence of ear infections and red paws. Sometimes they will even develop horrific skin infections secondary to the allergy which require antibiotics or antifungals.
Normally, in mild cases of allergy, I will recommend people try an antihistamine (you can contact your veterinarian for appropriate dosage) and wiping their pets paws or abdomen every night. In human allergy sufferers, they did a study that said that people who shower at night fair much better than those who shower in the morning. The thought is this is helpful because they rinse/wash off all the pollen and other irritants they were exposed to during the day rather than "marinating" in them overnight. This seems to work for dogs too.
In more severe cases, steroids, immunosuppressants and yes, allergy shots, just like people get can be helpful too. They are even coming out with allergy serum that does not need to be injected, but just given under the tongue to help combat allergies. There are a lot of similarities between humans and dog and cat allergies that you might not realize. So the next time it's allergy season and you are grabbing for a kleenex, try to see if your dog is licking at his/her paws or scratching at his/her ears. With vigilance, you may be able to catch the signs of seasonal allergies before you have to make a trip to the vet.