Elephant welfare can be assessed using two indicators

APRIL 1, 2020

by University of Turku

Across the world, animals are kept in captivity for various reasons: in zoos for education and research, in research facilities for testing, on farms for meat and other products, and in people's homes as pets. Maintaining good animal welfare is not only important for ethical reasons; poor welfare can impact human wellbeing and the economy. But how do we assess how animals are feeling?

One way to assess animal wellbeing is to look at stress levels. Vets typically use two biological measures of stress: stress hormone levels and white blood cell ratios. In mammals—including humans—the most important stress hormone is cortisol. When animals are faced with danger, cortisol is produced to help prepare the body for a challenge. However, if high stress and cortisol are experienced constantly, they can impact an animal's health.

In addition to cortisol, scientists can also look at the ratio of two types of white blood cells, heterophils (or neutrophils) and lymphocytes. These cells play an important role in the immune system of mammals, and after animals have experienced a stressful event, their ratio is typically high.

Researchers at the University of Turku, Finland, wanted to find out if these two biological measures of stress were correlated and whether animals with high levels of cortisol also had a high heterophil to lymphocyte ratio. They measured cortisol and heterophil to lymphocyte ratios in 120 Asian elephants from a semi-captive population of working timber elephants in Myanmar. The researchers also weighed each elephant, as body weight is a good indicator of general health.

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