Question:

Why is it that I'm so allergic to cats, but not to dogs?

Answer: The answer, in a word, is dander. It's like dandruff. The trigger for pet allergies is not their hair. In fact, cats that are short-haired traditionally give off more allergen (allergy-causing substance). Proteins found in the skin of pets trigger allergies in susceptible people. It flakes off, gets in their fur as dandruff, and spreads when the pet grooms itself with its tongue.

Veterinary research has shown that twice as many folks have cat allergies as dog allergies. It may be that the protein in a cat's skin is more allergy-provoking than a dog's, or simply that cats give off a greater quantity of dander.

Since dander collects in carpeting, the fabric of furniture, and bedding, it's better for pet-allergy sufferers to have hardwood or tile floors and leather furniture. If you have carpeting, steam cleaning it every three months will help reduce dander. Vacuum cleaner bags must have an ultrafine-particle HEPA filter, or else vacuuming will just put more dust and dander into the air. Allergic folks need to keep the dog or cat out of the bedroom. Washing the floors and walls every so often is a good idea, too.

Bathing dogs and cats every four to six weeks with a mild moisturizing shampoo will greatly cut down on the dander volume and the severity of pet-allergy symptoms.

For allergy medications, long-acting antihistamines like Claritin, Clarinex, Allegra, or Zyrtec help a lot. If asthma is triggered by the pet allergy, avoidance of pets is probably best. But if you're a pet lover and willing to suffer for your feline, I'd suggest talking with your doctor about treatment options like inhaled albuterol, inhaled steroids, and Singulair (a nonsteroid, anti-inflammatory pill). A long-term approach to overcoming pet allergies is allergy desensitization shots. It will take a couple of years with regular injections, but it will help in the long term.

nolead begins

Small nodes on fingers are arthritic bone spurs

Q:

My 75-year-old mother has osteoarthritis in her hands, knees, and back. She's now complaining about her hands, and I've noticed she has small protrusions of bone in several of her fingers. What causes those bony protrusions?

A: What you're describing are "osteophytes," commonly referred to as bone spurs. They're nontender growths of bone, especially common in folks with osteoarthritis, that develop over a long period of time in response to degeneration of cartilage. It's the body's feeble attempt to reduce movement of a joint that's wearing out from the effects of arthritis.

Those bumps you've noticed on your mother's fingers are called "nodes" - either Heberden's nodes if on the joint closest to the fingertip, or Bouchard's nodes if on the next closest joint to the fingertip. They're generally painless, and are more an indication of arthritis in the hand than a problem. Nothing needs to be done; the focus should be to treat the pain and inflammation of your mom's arthritis.

Bone spurs can also be found along the spinal bones, especially in the neck and low back. Sometimes they can cause pain, numbness, or weakness if they press against nerve roots that originate from the spinal cord. In the neck, they can occasionally press against the esophagus, causing pain or discomfort with swallowing. When bone spurs cause problems like these, a referral to a neurosurgeon or ENT specialist is advisable to see if surgery is needed.

A bit about heel spurs: There is poor correlation between the presence of a heel spur on X-ray and heel pain. While it's true that some heel spurs can cause pain, the vast majority do not. Most folks who have heel pain actually have a condition known as plantar fasciitis, an inflammation of the connective tissue that supports the tendons of the bottom of the foot.

Mitchell Hecht is a physician specializing in internal medicine. Send questions to him at: "Ask Dr. H," Box 767787, Atlanta, Ga. 30076. Personal replies are not possible.