Children from pet-owning families have stronger immune systems and are ill less frequently than other youngsters, research has shown.
Doctors who tested the saliva of 138 children found that those exposed to animals had more stable immune systems than those that were not, which meant they were better at fending off infection. They were also less likely to take days off school than other children.
Dr June McNicholas, a health psychologist from the University of Warwick who led the study, said: "Pet ownership was significantly associated with better school attendance rates. This was apparent across all classes, but was most pronounced in the lower school [classes one to three for age groups five to eight].
"Here, the pet owners benefited from up to 18 extra half-days' schooling per annum than their non-pet owning counterparts."
The researchers tested the children's saliva for the antibody immunoglobulin A (IgA), which is used as an indicator of immune system strength. The study showed antibody levels in pet-owning children were considerably more stable than in other children, indicating that they had robust immune systems.
The results appear to support the "dirty hypothesis", which argues that too much cleanliness early in life can weaken the immune system, a possible reason for the soaring rates of childhood asthma.
Dr McNicholas warned, though, that being too close to a pet could cause health problems. One of the biggest risks was a dog roundworm, which could cause stomach ache and eye damage.