Table 2.

Further detail of behavioural outcome measures used in the studies reviewed

Measure	Description	Evidence of validity of measure
Cat Stress Score (CSS):	A 7 rank linear scoring system based on key aspects of body posture and behaviour, rating cats from fully relaxed (1) to terrorised (7). Developed by Kessler and Turner [32], the CSS is a modification of the Cat Assessment Score (CAS) [40]	Evidence of correlative relationships with cortisol: creatinine ratios, but not consistent between studies [41,42], although this could be due to variation in study methodologies
		Good inter-observer reliability reported, however observer training required and there is no published training guide
		Important behaviours such as grooming are not included in the scoring system, neither are social behaviours towards conspecifics or the human observer (if they are present during scoring)
Cat Approach Test (CAT):	A 6 rank linear scoring system (from extremely friendly (1) to extremely unfriendly (6)) based on the response of cats to visual contact with a 4 year old male cat described as socialised with conspecifics. Cats were defined as socialized towards conspecifics when the mean of eight test ratings resulted in a score below 3.0, and non-socialized when they scored higher than 4.0. Developed by Kessler and Turner [35]	No evidence of previous attempts to validate
		No mention of inter-observer reliability
Human Approach Test (HAT):	A 6 rank linear scoring system (from extremely friendly (1) to extremely unfriendly (6)) based on the response of cats to a staggered human approach to their cage. Cats were defined as socialized towards people when the mean of eight test ratings resulted in a score below 3.0, and non-socialized when they scored higher than 4.0. Developed by Kessler and Turner [35], a modification of the Stranger-Approach-Test [40]	As above
Socialisation questionnaire	A linear scoring system based on information from multiple-choice questions (answered by the person relinquishing the cat) referring to the behavioural reactions of the cat in 10 specific situations when interacting with an unfamiliar and a familiar person, and five situations when interacting with an unfamiliar and a familiar cat. Developed by Kessler and Turner [35]	As above
Cortisol: creatinine ratio	Comparison of quantity of urinary cortisol with concentration of urine (as determined by quantity of creatinine present). Cortisol is an indication of physiological arousal, often used as an indirect measure of stress, although levels can vary with diurnal rhythm and other metabolic processes [41,43]	Assays based on in-house adaptation of previously validated measures [44,45]; some details not supplied in manuscript
		Evidence of correlative relationships between cortisol:creatinine ratios and CSS, but not consistent between studies [41,42], although this could be due to variation in study methodologies
		Evidence of correlative relationships between cortisol concentrations and the exposure to environmental stressors [43]
		Evidence that cortisol levels do not necessarily correlate with other physiological indicators of stress or compromised immunity [46]