animals, and that in two populations, adult female mink with bitten tails had relatively enlarged adrenal glands; in one of these latter groups of adults, tail-biters were also lighter, with less stored kidney fat. A slight but positive correlation was observed between tail-biting and stereotypy, but contradidctory results have also been obtained. We may also infer poor welfare when tail-biting results in physical injury, (whether self-inflicted or inflicted by neighbours; cases of fur-bitten and bleeding mink have contributed to at least one anti-cruelty lawsuit in the UK). However, there was no relationship between tail-biting and ’stick test’ assessments of temperament. Tail-biting may even positively correlate with litter size although this relationship is not always found. The acute stress of live grading just before pelting can also reduce tail-biting, possibly by reducing all activity. Anecdotally, several severe pelt-biters have been observed within a set of animals provided with swimming-water. Thus the relationship between pelt-biting and poor welfare is nearly as complex as that for stereotypy, with the provision that unlike stereotypy, there are fewer signs of positive correlates. Future studies could advance by standardising the techniques they use (e.g. live assessment versus assessment at pelting may give different results), by assessing tail-biters with a wider range of welfare measures, and by experimentally producing tail-biting by different means (e.g. manipulating nutrition, weaning age, etc.) to see if the correlates of tail-biting depend on its primary causal factors. In practice, here we will assume that treatments which reduce tail-biting by encouraging normal behaviours (e.g. playing), or by improving nutrition, also improve welfare. The welfare benefits of other approaches (e.g. selection), however, we will treat as rather less certain. $EQRUPDO EHKDYLRXUV ,,, $OOR GLUHFWHG RUDO EHKDYLRXUV The allo-sucking of tail-tips occurs in group-housed kits post-weaning up to the age of approximately 14 weeks; the welfare significance of this behaviour is unknown, although it may well represent a substitute for suckling. In older animals, occasionally large portions of the front part of the back and/or neck will be clipped of top hair, sometimes leaving only the head and back of the neck untouched. In contrast to tail-biting, this tends to be due to mink chewing each others’ fur, as it is almost absent in single-housed animals. In pair-housed or grouped kits, females tend to be bitten, and males to be allo-biters. Severe furchewing, which we can infer probably included allo-body-chewing, occurred in kits that were restrictively fed from September until pelting. In one study, peltbiting males showed more aggression, although it has been argued that allochewing and aggression are quite distinct, finding no relationship between it and the number of bite-marks through the skin. Pelt-biting males were also reported to be less curious, and to have higher levels of eosinophils than the recipients of the behaviour. This was taken as evidence of chronic stress in the allo-biters, although it should be pointed out that by inspection, their data seem to identify little difference between pelt-biters and the rest of the population as a whole, suggesting that 'recipients' were not a good control to use (see also 9.2). Indeed the ‘recipients’ seemed to have lower esosinophil levels than both biters and the rest of the population, suggesting that it is their welfare that was the most affected. Overall, therefore, this form of abnormal behaviour, and its welfare significance, is even less well understood than stereotypy and tail-chewing.
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