Changes in activity may range from total inactivity to maniacal hyperactivity depending on the species, the severity, source and location of the pain within the body. Painful conditions in specific locations may result in specific activities e.g. pain in the mouth may lead to quidding, animals with pain in the head region may twitch their ears or shake the head (Pollard et al 1992; Noonan et al 1994; Graf & Senn 1999; Faulkner et al 2000) and pain in the tail region may induce head turning to the tail or itching the tail on the floor or fence (Hay et al 2003).
After rubber ring castration of lambs and calves the animals get up and down (restlessness), foot stamp, kick, roll, bunny hop (jump), ease quarters, including arching the back and stretching (all summed to make up a composite score - REQ - see graphs), tail wag and head turn towards the source of pain. The incidence of these activities increases with the severity of pain until all the animal's time may be taken up performing them. Although some of these active responses have no obvious beneficial effects, they may be attempts to escape the pain.
Calves castrated with the rubber ring method react less violently than lambs but do show an increase in the above activities compared with untreated control calves. While calves castrated by Burdizzo show some of these activities earlier and for less time.
Animals with visceral pain show many of these activities at different intensities depending the species and age of the animal, the severity of the condition, the type of pain and whether the pain is acute or chronic. Horses with colic show rolling, pawing and stretching, while those with laminitis may show easing of limbs. After a laparotomy, rats back arch, wound lick, twitch and writhe.
Click on the animal icon below to see a movie of the behavioural response to visceral pain in lambs, calves, horses and rats:
Displaying some of these activities may make the animal conspicuous to predators and flock or herd 'mates' who may then attempt to take advantage of the situation to alter their position in the social hierarchy.
The animal may alter its strategy from active to passive attempts at pain avoidance by changing to abnormal 'still' postures and / or trembling. These latter behaviours are also seen immediately after surgical or traumatic injury (e.g. Burdizzo castration) when no analgesia is used (Hay et al 2003).
In chronic pain, some of the above activities may also be shown, but usually at a much lower incidence. This was demonstrated in preliminary work on calves and lambs during the seven weeks after rubber ring castration (see below) and in piglets three days after surgical castration, tail docking, ear notching and teeth clipping (All).
Calves and older lambs head turn and lick the wound produced after rubber ring castration. Calves also head turn apparently to nowhere and lift their hind legs alternately (leg lift). While calves mainly display this behaviour while standing, lambs have always been seen to lie down to head turn and lick the wound produced by ring castration. Pigs seem unable to head turn to the source of pain (possibly because of their conformation) and so tend to rub / itch the affected part on the floor (Hay et al 2003), other pen-mates, sow or inanimate objects like the pen fencing (itch quarters, ItQ) . Tail wagging (TW) and ear twitching (ET) were also increased in these piglets compared with untreated control and tail docked only piglets. Itching or rubbing the quarters, side or tail has been associated with a model of peripheral nerve damage in the tail of lambs (Jackson et al 1999). Itching the side/quarters may be related to referred pain from the viscera as seen in rats with inflammation of the uterus (Wesselmann & Lai 1997). The incidence of foot stamping, easing and itching quarters and tail wagging were increased with the presence of inflammatory lesions at the neck of the scrotum after ring castration of older (six weeks old) lambs. However, the incidence of these activities was lower than during the acute pain. Chronic pain is more difficult to detect than acute pain.
Itching may also be seen in animals infested with external parasites or other skin conditions e.g. Psoroptes ovis (Sheep Scab mite).