Perseverative and habitual tail-chasing described by Kennel Club group.

Breeds are grouped according to the Kennel Club, which takes into account the breed history and general usage. They can also be grouped both genetically, as described by Parker et al. (2007), but those data are not shown here because not all recognised breeds have been genetically characterised according to that system to date. Representative breeds that showed perseverative or habitual tail-chasing are listed for each breed group; these were identified from uploader descriptions, or if no breed was stated, the breed was estimated from the appearance of the dog. Only those videos that included a potentially distracting event (n = 198) are included in the figures for perseveration, and only those with comments describing the tail-chasing frequency (n = 86) are included in the habitual chasing calculations.