Symptoms of Stress
Hormonal indicators
Stress can be identified by quantitative measures of adrenal hormones in the blood plasma or urine. However, it must be remembered that hormone levels may vary naturally between individuals and with time of day. Collection and handling procedures may also cause stress themselves.
Behavioural and physiological indicators
- Facial expressions (fear, anxiety)
- Vocalisation
- Increased heart rate
- Rapid breathing
- Overheating (excessive licking, panting, salivating)
- Elevated frequencies of aggressive behaviour
Stereotypic behaviours
Repetitive, irrelevant actions may develop out of chronic stress situations (stereotypic behaviours).
Performance of such repetitive behaviour may act to selfstimulate the production of endorphins, which act on the pleasure centres of the brain to reduce pain and stress.
For example, over-grooming in dogs and cats, tail biting in pigs, feather plucking.
Abnormal behaviours such as those mentioned are usually brought about by overcrowding, boredom, lack of bedding, poor ventilation, disease and malnutrition.
Some abnormal behaviours are, however, a consequence of new environments rather than stress.