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

Abstract

Core body temperature (CBT) rhythm, locomotor activity, and actigraphy-sleep were evaluated in geriatric dogs with cognitive dysfunction. Dogs ( n =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, p <0.001), and was the highest at 19:00C. CBT at 19:00 was positively related ( p <0.01) to memory ( r (31) = 0.50) and 3-domain cognitive performance index (memory, learning, attention; r (31) = 0.39). Total daytime or night-time activity did not differ between memory groups, but hourly counts at 8:00 were positively related ( p <0.05) to memory ( r (31) = 0.52), learning ( r (31) = 0.36), and 3-domain cognitive performance index ( r (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 ( r (31) = −0.39; p <0.05) and BT at 15:00 (r (30) = −0.51; p <0.01). Lower peak BT and inc r 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.

Eye and Ear Temperature Using Infrared Thermography Are Related to Rectal Temperature in Dogs at Rest or With Exercise

“…The daytime temperatures measured between 09:00 and 14:30 were obtained while the dogs were considered sedentary and did not exhibit the natural diurnal fluctuation of BT that normally increases 0.5–0.8°C from early morning (08:00–10:00) and peaks between 17:00 and 20:00 (17, 30, 31). This lack of diurnal fluctuation was observed across all three methods, and as shown in Figure 1, the temperatures were relatively consistent or slightly declined over the day.…”

Essential Oils and Melatonin as Functional Ingredients in Dogs

“…Probably, according to the authors, dosing problems or frequency could explain these results [ 142 ]. Zanghi et al (2016) suggested that in older dogs, the decrease in locomotor activity and insomnia could be related to a gradual degenerative neuronal disconnection between dorsal, dorso-medial, and ventral subparaventricular zones within the paraventral hypothalamic nucleus that regulates circadian melatonin release [ 143 ]. Additionally, in a comparative study, Lefman and Prittie (2019) proposed future studies to improve psychogenic stress in hospitalized veterinary patients treated with diazepam, midazolam, alprazolam, lorazepam, dexmedetomidine, trazodone, and melatonin, through therapies less aggressive and healthier [ 144 ].…”

Fundamental Concepts of Human Thermoregulation and Adaptation to Heat: A Review in the Context of Global Warming

“…Although there are multiple modes of adaptation to achieve such behavior, this review would like to highlight the likelihood of a shift in circadian cycle as a potential strategy, because of its impact on normality of human lifestyle globally. Whether by design or nature, the heat-avoidance behavior would likely lead to shift in circadian cycle towards a sub-nocturnal lifestyle [140,234], especially for populations who are involved in outdoor work and sports, and who do not have access to AC [136,235]. To avoid the heat from the sun, outdoor activities would likely begin closer to, or soon after sunset, and could extend to the next morning before dawn, or soon after sunrise.…”