TABLE 1.

Different methods used to quantify visceral pain in laboratory animals

Animal	Animal model	Method	Purpose of the study	Findings	References
Mice	Experimental study	Telemetry	To study post laparotomy pain in laboratory mice by telemetric recording of heart rate and heart rate variability	Real‐time telemetric recordings of heart rate and heart rate variability found to be indicative of mild to moderate post laparotomy pain which cannot easily be detected by direct observation	Arras et al 57
Rat	Inflammatory	Intracolonic manometry	To test the efficacy of pregabalin on visceral pain responses and colonic compliance	Pregabalin reduced the viscerosomatic and autonomic responses associated with CRD induced visceral pain and increased colonic compliance	Ravnefjord et al 62
Mice	Inflammatory	Automated behavior analysis	To automate analysis of abdominal licking behavior associated with intraclonic capsaicin induced visceral pain	The neurokinin‐1 receptor antagonist GR205171A dose dependently inhibited capsaicin induced licking which was automatically detected by applying commercially available image analysis software	Hayashi et al 54
Mice	Inflammatory	Burrowing	To investigate whether a change in burrowing behavior is a sensitive measure of animal welfare in murine models of colitis	Changes of spontaneous burrowing behavior correlate with the onset of inflammation in acute DDS induced colitis	Jirkof et al 53
Rat	Inflammatory	Electrophysiology & behavioral studies	To study the reactive oxygen species mediated visceral pain related amygdala plasticity and behaviors	ROS contribute to visceral pain related hyperactivity of amygdala neurons and amygdala dependent behaviors through a mechanism that involves increased excitatory transmission and excitability of CeA neurons	Ji et al 73
Rat	Stress	EMG	To study MS induced visceral hypersensitivity	Visceral hypersensitivity of MS rats is more pronounced in the post‐weaning period and slightly restored in adults. Thus, visceral hypersensitivity in the post‐weaning period might play a more meaningful pathophysiologic role in the formation of adult irritable bowel syndrome	Li et al 63
Rat	Inflammatory	RGS, burrowing, CBS	To assess whether the RGS, CBS and burrowing could identify pain in an acute and chronic colitis model	RGS increased as DAI scores increased during both acute and chronic phases. Burrowing only decreased during the acute phase but CBS scores did not increase significantly during either colitis phase	Leung et al 49

Abbreviations: CBS, Composite Behavior Score; CeA, Central Amygdala; CRD, Colorectal Distension; DAI, Disease Activity Index (assessing fecal blood, stool consistency and weight loss); DDS, dextran sulfate sodium; EMG, electromyography; MS, maternal separation; RGS, rat grimace scale.