In order to rule out an influence of otitis or concomitant neurological disease on itching behaviour [22] and IL-31 levels, difference between IL-31 levels in serum and CSF of dogs with and without itching behaviour were compared separately in dogs with syringomyelia only (group A.1), with syringomyelia and otitis (group A.2), and dogs with syringomyelia and concomitant neurological disease (A.3) respectively. This evidence concerns the gene IL31 and ear infection.