Being around the family cat or dog at 3 months of age may offer protection against allergies to dust mites and pollen later on, but does not appear to impact the development of asthma by the age of 8 years.
Dr. Marjan Kerkhof, of the University Medical Center Groningen in the Netherlands, and colleagues studied the effects of pets in the home on the development of asthma and allergies to airborne "triggers" in 2951 children who were assessed annually up to age 8.
At the age of 3 months, 34 percent of the children lived with a cat in their home while 16 percent lived with a dog, the researchers report in the journal Allergy.
Children with a cat or dog in the home at 3 months of age were less apt to be "sensitive" to various inhaled allergens at age 8, the researchers found. Having a pet in the first year of life "should not be discouraged in order to prevent later allergies in the child," Kerkhof told Reuters Health.
However, the results also suggest that the presence of a dog after the first two years carries a "somewhat greater risk of airway symptoms," Kerkhof noted.
Among children exposed to a dog in the home after the age of 2 years, 3.9 and 10.6 percent, respectively, developed wheeze and a dry cough at nighttime, over the subsequent year.
These asthma-like symptoms were evident after allowing for other factors associated with symptoms of airborne allergy, including exposure to other pets, children, and smoking; gender; family history; and duration of breast feeding.
By contrast, among children not exposed to a dog, 2.8 and 8.4 percent developed wheeze and dry cough.
Yet, the investigators found no association between asthma diagnoses in the first 8 years of life and having a cat or dog in the home. They likewise report that removal of a cat or dog from the home had no influence on the development of asthma among children without previous asthmatic symptoms.
Since asthma is such a diverse disease, with different types associated with different allergen exposures, Kerkhof's team calls for continued long-term investigations to identify links between childhood pet exposures and later asthma.