Doctor, doctor: Dr Tom Smith answers your questions

What are the dangers of having a dog in a family with young children? Barack Obama is getting one for his daughters - we are thinking of doing the same.

There are pros and cons, of course. If you keep a dog in the house, you are at higher risk than are other people of being bitten. That's especially true if you have a small child. Some dogs react aggressively to the high-pitched tones of a child's voice, and screams only make them more aggressive, which may be why there are regular reports of toddlers and infants being savaged. Many years ago, a study of consecutive serious bites in a hospital casualty department found male dogs to be in the vast majority, so preferably choose a bitch and make sure that she is very well trained. Your children will need to be hygiene-aware, too. On the plus side, they do get pleasure and learn a lot from living with a well trained, obedient and affectionate dog.

We have heard mixed messages about the causes of cancer. Our father died of stomach cancer at 55. We were told then that it was related to his heavy drinking. Now we hear that it is induced by an infection. Which is correct?

Both are probably involved. It's thought that the alcohol inflames the stomach wall, and that Helicobacter pylori, bacteria known to cause stomach ulcers, then initiate a cancerous change in the inflamed area. Eradicate Helicobacter (it means a short course of drugs) and the cancer may not develop. Giving anti-Helicobacter drugs to men and women whose stomachs show early 'pre-cancerous' changes has been shown to prevent them developing into cancer.

Our baby son has a little fleshy lump that appears just to be thickened skin in front of his left ear. It doesn't seem to bother him. Is it important?

It sounds as if he has a 'skin tag' in front of his ear. They are very common at birth, and tend to be much less conspicuous as the child grows. This year an Israeli study found that tags and 'pits' in front of a newborn's ear may be a sign of hearing loss. To be sure your son is hearing normally, ask your doctor to follow this up.

Do you have a question for Dr Smith? Email doctordoctor@guardian.co.uk

Thanks to guardian.co.uk who have provided this article. View the original here.