Water intake and consumption behaviour of colony and privately-owned healthy domestic cats fed 100% dry, 50% dry and 50% wet, and 100% wet diets: A comparison of research and home environments

Dietary moisture is a key determinant of hydration in domestic cats. Yet the effects of feeding isoenergetic diets with varying moisture content on free and total water intake (FWI; TWI), drinking behaviour, and the translation of findings from a controlled colony to home environments remain poorly characterized. The objective of this study was to evaluate how dietary moisture influences total and free water intake and postprandial versus fasted drinking behaviour in cats fed isoenergetic extruded and canned diets, and to assess whether hydration outcomes observed in colony-housed cats are consistent with those measured in privately owned cats living in home environments. Twelve colony-housed male cats and ten privately owned mixed sex cats sequentially fed three diets for two weeks each: (1) 100% dry, (2) 50% dry and 50% wet, and (3) 100% wet. Water intake volume, drinking duration, and event frequency were continuously recorded using Felaqua Connect water fountains. Data were analyzed using repeated-measures mixed linear models with treatment as the fixed effect and individual cat as the random effect across days. Drinking behaviour relative to meal timing was also evaluated using a repeated-measures approach. A second linear mixed-effects model was fitted, with treatment, environment (colony versus privately owned), and their interaction as fixed effects and individual cats included as a random effect. Estimated marginal means and Tukey-adjusted contrasts were computed for all treatment x environment comparisons. Daily FWI was greatest on the dry diet, whereas TWI was greatest on the wet diet for both groups of cats (P < 0.001). Across all treatments, cats had a higher FWI during the postprandial period than during the fasted period (P < 0.001). Privately owned cats consumed greater FWI and TWI than colony-housed cats across all dietary treatments (P < 0.001). However, strong positive correlations in daily FWI (r ≥ 0.87; P < 0.001) and TWI between environments (r ≥ 0.79; P < 0.001) indicated a similar response to changes in dietary moisture across environments. Transient increases in water intake were observed for approximately 24 hours following dietary transitions. This study compares cat drinking behaviours in colony and home settings and provides novel evidence that cats consistently consume more water in the postprandial period, regardless of dietary moisture content.