Here is an article backing up Chad's retort about cat's and childhood allergies:
Cats Can Prevent Childhood Asthma
But Kids With Asthmatic Moms Should Avoid Pets By Daniel DeNoon
Sept. 5, 2002 -- When the cat's away, allergies will play. A flurry of reports shows that furry friends protect most children from developing asthma and other allergies. The exception: kids whose moms have asthma.
Doctors once advised parents to get rid of pets if they were worried about their kids developing allergies. New studies suggest that this advice is wrong -- except for kids born to mothers that have asthma.
A study released last week showed that infants raised in homes with two or more pets had fewer allergies. Two more studies -- one in the Sept. 7 issue of The Lancet and the other in the Sept. 1 American Journal of Respiratory and Critical Care Medicine -- show that kids raised in homes with cats have less asthma and wheezing. Unlike the earlier study, neither found a significant effect for dogs.
The Lancet article looked at 448 kids with a father or mother who suffered from asthma. Juan C. Celedón, MD, DrPH, and colleagues at Brigham and Women's Hospital, Boston, found that having a cat around the house when they were babies reduced asthma and wheezing as the children reached age 1. The protection continued to increase until the end of the study, when the children were 5 years old.
But a closer look showed that some of the kids wheezed more if they had a cat. These were the kids whose moms suffered from asthma.
"For most children, exposure to a cat seems to be beneficial," Celedón tells WebMD. "However, we did find that there is a caveat. Children with maternal history of asthma have increased risk of wheezing when exposed to cats."
The second study, by University of Virginia researcher Matthew Perzanowski, MPH, and colleagues, surveyed more than 3,400 Swedish children. They found that kids with cats were less likely to have asthma than kids without cats. Weaker protection was seen for having a dog.
This doesn't mean that pregnant couples should rush out and buy a cat, says Daryl Zeldin, MD. Zeldin heads the asthma program at the National Institute of Environmental Health Sciences. And kids who already have asthma won't be helped.
"Kids who are already allergic should not get a cat," Zeldin warns. "I think things are less clear for an unborn child. Do you buy a cat when mom is pregnant? Some studies suggest it is reasonable, but if mom is asthmatic you increase the risk. It is not that clear cut. The standard recommendation still will be if you are allergic to cats, you shouldn't have cats in the home. But this data suggests that exposure to [allergy triggers] early in life may actually reduce chances a child will get asthma."
Zeldin says there are two theories why this might happen. The first is the traditional "tolerance" theory. It holds that exposure to allergy triggers -- at the right time and in the right amount -- changes the way the immune system responds to them.
The second theory is the "hygiene" theory. It holds that kids kept in too clean an environment will suffer more allergies because their immune systems have no chance to adapt to allergy-causing substances. Supporting this idea, Zeldin says, are data showing that early exposure to farm animals, day-care-centers, and pets protects children from allergy and asthma.