Kitchen Tip and Itchy Dogs.

This column is going to be about itchy dogs but first I have an important kitchen tip. Boiling water can explode in your microwave.

When I boil water for tea in a Pyrex cup, sometimes I forget to take it out and make the tea. So 5 minutes or so later, just to make sure it's still hot, I microwave it again. Sometimes it explodes. This doesn't happen all the time but when it does, it's exciting. It also seems dangerous to me.

I think what happens is this: When it boils the first time, there are - even in a clean cup with plain tap water - miniscule particles of dust or other things in the water. This provides places for the boiling to start a little at a time, at a slightly lower temperature, before the whole cup of water reaches the boiling point. When you boil it the second time, however, all the little particles may have been boiled away. In a microwave there may not be "hot spots" and boiling may not start until the whole cup is ready to boil. When it does, there is a loud pop that rattles the door and most of the water winds up all over the inside of the microwave. Maybe a physicist will read this and either verify it or correct me if I'm wrong.

I've written about itchy dogs before but it's one of the most common problems that dogs have. By far the most common cause is an allergy to something in the air, like pollen, house dust, cat dander, etc. A dog with allergies may be worse in the spring and fall, when there is more pollen in the air.

Allergies to those things are also common in humans and recent studies have shown humans who are raised in more affluent countries, in cleaner conditions, are significantly more likely to have allergies. I know of no studies like that in dogs, but some veterinarians think dog allergies are more common now than 50 or 100 years ago.

No lab test will tell for sure that the problem is an allergy. Other things that can cause itching - like mange, fleas, skin infections, food allergy - should be ruled out, possibly using blood tests, skin biopsies, or other tests. Then we assume it is allergy and begin treatment.

A drug called prednisone is the mainstay of treatment. Humans can have pretty bad side effects to prednisone but dogs and cats are much more tolerant of the drug. If itching can be controlled with conservative, intermittent prednisone pills, that is often the best way to manage allergy.

Antihistamines, like "Benadryl," are cheap and safe and may help. A nutriceutical - omega fatty acids - also may help. These will rarely control itching by themselves, but may reduce the dose of prednisone required.

If it takes too much prednisone to control allergy, allergy shots may be worth considering. If we are pretty sure allergy is the problem, a blood test may show what the dog is allergic to. Then special allergy shots are made up. The owner gives the shots at specified intervals. This can cost several hundred dollars and may not work very well.

There is another injection that can be used, called cyclosporine that may be effective. It is significantly more expensive than prednisone and also can have serious side effects. The good news is that in most allergic dogs, itching can be controlled by a regime of prednisone, which is cheap and relatively safe. The bad news is that if prednisone doesn't work, the problem is considerably more challenging.