TABLE 3-1Behavioral Signs of Persistent Pain

SignExplanation
GuardingThe animal alters its posture to avoid moving or causing contact to a body part, or to avoid the handling of that body area.
Abnormal appearanceDifferent species show different changes in their external appearance, but obvious lack of grooming, changed posture, and a changed profile of the body are all observable signs. In species capable of some degree of facial expression, the normal expression may be altered.
Altered behaviorBehavior may be depressed; animals may remain immobile, or be reluctant to stand or move even when disturbed. They may also exhibit restlessness (e.g., lying down and getting up, shifting weight, circling, or pacing) or disturbed sleeping patterns. Large animal species may grunt, grind their teeth, flag their tail, stomp, or curl their lips (especially sheep and goats). Primates in pain often roll their eyes. Animals in pain may also show altered social interactions with others in their group.
VocalizationAn animal may vocalize when approached or handled or when a specific body area is touched or palpated. It may also vocalize when moving to avoid being handled.
MutilationAnimals may lick, bite, scratch, shake, or rub a painful area.
SweatingIn species that sweat (horses), excessive sweating is often associated with some types of pain (e.g., colic).
InappetenceAnimals in pain frequently stop eating and drinking, or markedly reduce their intake, resulting in rapid weight loss.

From: 3, Recognition and Assessment of Pain

Cover of Recognition and Alleviation of Pain in Laboratory Animals
Recognition and Alleviation of Pain in Laboratory Animals.
National Research Council (US) Committee on Recognition and Alleviation of Pain in Laboratory Animals.
Washington (DC): National Academies Press (US); 2009.
Copyright © 2009, National Academy of Sciences.

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