Table 3. Perseverative and habitual tail-chasing described by Kennel Club group.

Kennel Club Breed group	Total tail-chasing videos (n)	Perseveration				Tail-chasing frequency
		Distractible (n)	Perseverative (n)	Percentage perseverative	Breeds exhibiting perseveration	Rare (n)	Periodic (n)	Habitual (n)	Percentage habitual	Breeds exhibiting habitual tail-chasing
Gundog	56	22	8	26.7	Goldendoodle, Golden Retriever, Labrador	2	9	3	21.4	Labrador, Springer Spaniel
Hound	21	9	3	25.0	Beagle, Dachshund	1	1	0	0.0	N/A
Pastoral	28	5	0	0.0	N/A	1	5	1	14.3	Shetland Sheepdog
Terrier	86	28	20	41.7	American Staffordshire Bull Terrier, Jack Russell Terrier, Patterdale Terrier, Pitbull, Staffordshire Bull Terrier, Yorkshire Terrier	3	7	6	37.5	American Staffordshire Bull Terrier, Jack Russell Terrier, Patterdale Terrier, Pitbull Terrier, Staffordshire Bull Terrier
Toy	56	11	14	56.0	Chihuahua, Havenese, Papillon, Pekingese, Pug	3	10	2	13.3	Chihuahua, Shih Tzu
Utility	29	10	3	23.1	Lhasa Apso, Shih Tzu	0	4	2	33.3	Lhasa Apso
Working dog	24	7	5	41.7	Bernese Mountain Dog, Boxer	1	2	0	0.0	N/A
Crossbreeds	100	30	23	43.4	N/A	0	11	12	52.2	N/A

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.