Table 1. Brief description of behavioural data collected from YouTube, and associations between them.
| Behavioural characteristic | Description | Proportion of videos showing the characteristic (excluding videos with missing values) | Significant associations (↑ = positive association; ↓ = negative association | Odds ratio +/− S.E.; DF; P-value |
| Tail-chasing frequency as indicated by uploader comments* | ‘Habitual’ (e.g. daily, “all the time”, “a lot”, “spends hours” tail-chasing, the dog is “obsessed”);‘Periodic’ (e.g. “from time to time”, “regularly”, “[the dog] usually tail-chases when…”);or ‘Rare’ (e.g. “[the dog] rarely does this”, I “managed to catch” the dog tail-chasing) | Habitual: 26/86 (30.2%);Periodic: 49/86 (57.0%);Rare: 11/86 (12.8%) | ↑Difficult to distract | 8.06+/−2.50; 9; 0.049 |
| “ | “ | “ | ↑ ‘Stupid’ in uploader comments | 6.52+/−2.33; 23; 0.037 |
| Difficult to distract | The dog did not stop chasing for more than 5 s despite a potential distraction (e.g. the owner commanded the dog to do something other than tail-chase, a sudden noise, or the dog collided with something hard enough to impede its progress) | 76/198 (38.4%) | ↓Play | 0.16+/−1.70; 102; 0.001 |
| “ | “ | “ | ↓Encouragement | 0.28+/−1.40; 102; 0.000 |
| “ | “ | “ | ↑ ‘Funny’ in public comments | 6.82+/−2.09; 24; 0.016 |
| “ | “ | “ | Also see Habitual tail-chasing frequency | - |
| Vocalisations heard during or within 5 s of tail-chasing | Barking | 54/366 (14.8%) | ↓Television and computer use | 0.30+/−1.51; 201; 0.004 |
| “ | “ | “ | ↑Tail wagging | 2.30+/−1.45; 201; 0.026 |
| “ | Growling | 75/353 (21.2%) | ↑Hunter Group (Parker et al., 2007) | 2.66+/−1.63; 83; 0.050 |
| “ | “ | “ | ↑Age (i.e. adults) | 2.30+/−1.40; 206; 0.013 |
| “ | Whining | 4/354 (1.1%) | (too rare to test) | - |
| Collision | Dog collided with an object during or up to 30 s after tail-chasing | 101/393 (25.7%) | ↓Play | 0.37+/−1.53; 262; 0.019 |
| “ | “ | “ | ↑Laughter | 2.12+/−1.32; 230; 0.007 |
| Play behaviour | Within 5 s of a chasing bout, the dog exhibits a play bow (characteristic posture with the forelegs extended on the ground), object play (manipulation of a toy or other available object), social play (with human or conspecific), or locomotor play (e.g., bounding, rolling) | 66/389 (17.0%) | ↑Tail wagging | 3.89+/−1.40; 259; 0.000 |
| “ | “ | “ | ↓Age | 0.24+/−1.39; 259; 0.000 |
| “ | “ | “ | ↑Outside | 3.26+/−1.63; 260; 0.016 |
| “ | “ | “ | ↓Funny | 0.04+/−3.60; 68; 0.023 |
| “ | “ | “ | Also see Difficult to distract, and Collisions | - |
| Tail wagging | Dog rhythmically moves its tail laterally at least twice in each direction within 5 s of a chasing bout, rather than it remaining inanimate or moving irregularly | 135/393 (25.7%) | ↑Age | 2.77+/−1.36; 207; 0.001 |
| “ | “ | “ | ↑Television and computer use | 2.15+/−1.33; 237; 0.008 |
| “ | “ | “ | ↑Mastiff-terriers | 2.67+/−1.63; 84; 0.046 |
| “ | “ | “ | Also see Play Behaviour and Barking | - |
| Mouths tail | Dog is clearly seen to bite, lick or hold the tail or hindquarters/hind leg in its mouth for at least 1 s | 248/392 (63.3%) | ↑Laughter | 1.78+/−1.27; 235; 0.018 |
| “ | “ | “ | ↑‘Stupid’ in uploader comments | 4.16+/−1.67; 154; 0.006 |
When videos had no sound-track or the soundtrack was replaced by music, missing values were recorded for data reliant on sound; similarly missing values were recorded for videos without relevant comments or where the behaviour could not be clearly seen. The proportion of tail-chasing videos (excluding those with missing values) showing each characteristic is displayed, along with any significant associations with relevant predictors, for which the odds ratios, degrees of freedom, and P-values are displayed. *This odds ratio was calculated from a model using ‘Habitual’ vs other frequencies as a binary variable.