We generally differentiate between acute pain and chronic painPain The negative sensory or emotional experience that indicates awareness in the animal of injury or the threat of injury to the body. This negative experience induces changes in an animal’s behavior and physiology, intended to limit the effect of, or avoid the injury, to reduce the chances of repeated injury and to promote recovery.. Acute pain (post-surgery or disease-related) is often characterized by a number of behavioural changes, such as aggression, isolation in the group, restlessness and self-mutilation, as well as by autonomic reactions such as dilated pupils and rapid breathing.

Chronic pain

With chronic pain, such as seen with tumorsTumor Neoplasm, new growth. Is predicated upon autonomous growth of cells or tissues into benign or malignant tumors., notable effects may be poor overall condition, piloerection, social isolation and a hunched posture. The animals will lose weight and are less active. Diseased mice tend to take in little water, which will lead to rapid dehydration (see picture). 

Pica- behaviour

When mice are in either acute or chronic pain, they may start to engage in pica-behaviour, which is defined as eating bedding material or other strange, non-food objects (see movies).