Black Cats May Bring More Than Bad Luck


From the WebMD Archives

Jan. 19, 2001 — As children, we learn the old saying that bad luck follows if a black cat crosses your path. Now doctors are telling us that the bad luck may show itself in the form of sniffling and sneezing. According to new research, dark-colored felines may actually be more likely to cause allergic reactions in their owners than cats with lighter fur.

Physicians at Long Island College Hospital (LICH) in Brooklyn, N.Y., surveyed 321 patients about how many cats lived with them, how long they’d owned them, and the color of their cats. The researchers also graded the severity of each person’s allergic reaction.

They found that patients with dark-colored felines were four times more likely to have allergic symptoms linked to the pets than were those who owned light-colored cats.

“We wanted to look at the physical characteristics of pets concerning allergies,” says Shahzad Hussain, MD, of the LICH department of allergy and immunization. “This was a very subjective study. We were surprised by the results.”

He tells WebMD that other researchers previously have shown that female cats tend to produce more of an allergen called fel d1 than do males. Now Hussain and his team want to find out if this protein in cats’ skin and saliva may also be more abundant in dark-colored animals. “What accounts for the difference [in allergic reactions] is not known,” says Hussain of what he calls a “statistically significant” difference in allergy severity in owners of dark-colored cats.

One theory that Hussain says they will investigate is whether the fact that the higher amount of melanin, which accounts for the darker pigmentation, may also cause higher production of fel d1 and, therefore, more allergic reactions.

Mark Millard, MD, medical director of the Baylor University Medical Center Asthma and Pulmonary Rehabilitation Center in Dallas, says that cats in general tend to cause more of a problem when it comes to allergies than do dogs.

According to the American College of Allergy, Asthma, and Immunology, more than 70% of American families own a cat or dog. The American Humane Society estimates the U.S. cat population is nearly 60 million. That’s a lot of potential allergies, which can progress to more serious and even fatal diseases such as asthma.

“Cat dander is very volatile, and it sticks to things,” Millard tells WebMD. “So just getting the cat out of the house is not enough.”

He says that it’s important to have objective allergy testing because a cat is not necessarily to blame just because someone has itchy and watery eyes, a runny and itchy nose, and repeated sneezing attacks. However, Millard recommends that if a cat is the problem, the best thing to do is to get rid of it — although this is solution is often not very popular.

“You must be careful about recommending to get rid of a cat,” he says. “There is an old joke that most people would get rid of the allergist before they get rid of their cat.”

Some studies have shown that washing a cat can keep the allergen-containing dander down and help to alleviate allergy symptoms. Hussain and Millard say that washing the cat once a week may help, but it’s not a solution either because the sticky dander and saliva can remain in the house for six weeks to six months whether the cat is gone or kept clean.

Hussain’s survey also showed that patients were 20 times more likely to suffer allergic reactions if they allowed their dark-colored cats in the bedroom. He suggests that if the cat must be in the house, especially in the bedroom, then the carpets should be removed in favor of wood, vinyl, or tile floors.

According to Millard, however, trying to keep the cat out of the bedroom won’t really help — again because of the stickiness of the dander and saliva and also because, as he says, “a cat sleeps anywhere it wants.”

Living in a cat-free, dust-free, smoke-free environment is the best way to prevent allergies and asthma, says Millard. However, because people become so attached to their pets, allergy sufferers who already have cats or dogs living in their houses are unlikely to give their animals permanent vacations.

So Millard advises keeping the house and the pet as clean as possible. This includes washing bed linens often using hot water; this eliminates the fur, dander, and saliva and also allergy-causing dust mites.

But pet-loving folks who are sent into sneezing fits when the critter is near should remember Millard’s last piece of advice: “When you wash the cat, don’t confuse it with washing the dust mites; don’t wash the cat in 130-degree water.”

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