Paw preference in dogs: relations between lateralised behaviour and immunity.

Paw use in a task consisting of the removal of a piece of adhesive paper from the snout was investigated in 80 mongrel and pure-bred domestic dogs (Canis familiaris). Population lateralisation was observed, but in opposite directions in the two sexes (animals were not desexed): males preferentially used their left paw, females their right paw. The relationship between immune function and paw preference was then investigated. Some immune parameters (total number of white blood cells including lymphocytes, granulocytes and monocytes; leukocyte formula; total proteins; gamma-globulins) were investigated in a sample of left-pawed (n = 6), right-pawed (n = 6) and ambidextrous (n = 6) dogs. The results showed that the percentage of lymphocytes was higher in left-pawed than in right-pawed and ambidextrous dogs, whereas granulocytes percentage was lower in left-pawed than in right-pawed and ambidextrous dogs. Moreover, total number of lymphocytes cells was higher in left-pawed than in right-pawed and ambidextrous dogs, whereas the number of gamma-globulins was lower in left-pawed than in right-pawed and ambidextrous dogs. These findings represent the first evidence that brain asymmetry modulates immune responses in dogs.