Diurnal changes in core body temperature, day/night locomotor activity patterns, and actigraphy-generated behavioral sleep in aged canines with varying levels of cognitive dysfunction

• Published in: Neurobiology of sleep and circadian rhythms Vol. 1; no. 1; pp. 8 - 18
• Main Authors: Zanghi, Brian M, Gardner, Cari, Araujo, Joseph, Milgram, Norton W
• Format: Journal Article
• Language: English
• Published: United States Elsevier 01.10.2016
• Subjects: Body temperature; Circadian rhythm; Cognition; Diurnal; Dog; Research Paper; Spatial working memory; Spatial working memory; Cognition; Circadian rhythm; Diurnal; Dog; Body temperature
• ISSN: 2451-9944; 2451-9944
• DOI: 10.1016/j.nbscr.2016.07.001

Core body temperature (CBT) rhythm, locomotor activity, and actigraphy-sleep were evaluated in geriatric dogs with cognitive dysfunction. Dogs ( =33; 9-16 yrs) performed a spatial working memory task and divided into three memory groups: Low, Moderate, and High, with subsequent evaluation of learning and attention. Rectal CBT was recorded 6 times over a 17.5 h period and Actiwatch® activity monitoring system for 5 days while housed indoors with 12 h light/dark schedule. Rhythm of daily activity data was evaluated using the traditional cosinor analysis and generation of non-parametric measures of interdaily stability, intradaily variability, and relative amplitude. CBT differed with time (F (5, 130)=11.36, <0.001), and was the highest at 19:00C. CBT at 19:00 was positively related ( <0.01) to memory ( (31) 0.50) and 3-domain cognitive performance index (memory, learning, attention; (31) 0.39). Total daytime or night-time activity did not differ between memory groups, but hourly counts at 8:00 were positively related ( <0.05) to memory ( (31) 0.52), learning ( (31) 0.36), and 3-domain cognitive performance index ( (31) 0.53). There were no significant differences between age or memory groups for any circadian rhythm measures. Daytime naps were inversely related to memory accuracy ( (31) -0.39; <0.05) and BT at 15:00 (30) -0.51; <0.01). Lower peak BT and inc eased napping may predict some aspects of cognitive performance of working memory, learning, and/or attention processes in these geriatric dogs, but minimal diurnal rhythm disruption of locomotor activity is observed when these cognitive processes decline.