Stress has an important role to play in the survival of any species but it becomes a problem when it is ongoing and an animal is unable to cope.
Stress of any kind impairs the body's ability to heal and impacts their quality of life. Stress and anxiety can predispose to a number of health issues including infections, allergies, skin problems, bladder inflammation in cats and a number of other diseases.
Symptoms of stress can include behavioural changes, obsessive licking or chewing, aggression, depressed behaviour or hiding, barking and even diarrhoea to name but a few.
A number of factors can cause stress and anxiety including extreme weather, fireworks, storms, moving house, changes in routine, feeling unwell, not getting enough exercise, overcrowding, the loss of another pet or owner, or even not knowing their place in the family "pack" or being constantly badgered by another animal, eg. a newly introduced cat in the area or a new puppy that just wants to play the whole time when the old dog needs to rest.
Limiting stress by getting to the root of the problem and avoiding stressful situations is ideal but sometimes this is impossible. In these cases it is important to help the animal to cope with the stress as effectively as possible.