Humans and their pets may be very similar in terms of psychiatric behaviour, according to a new Australian study involving a psychiatrist and an animal behaviourist.
Associate Professor Judith Blackshaw of UQ’s School of Veterinary Science and Emeritus Professor Ivor Jones of the University of Tasmania are developing a new evolutionary model for psychiatric disturbances common to animals and humans.
They are writing a popular book on syndromes including aggression, depression, anxiety states, phobias, eating disorders, self-injury and immobility.
Dr Blackshaw said up to 50 percent of veterinary science clinical consultations were associated with some aspect of animal behaviour.
“American vets report that it’s not uncommon for some owners to be on Prozac (a mood altering drug) and their pets on similar drugs,” she said.
“A recent interesting development in veterinary practice is that practitioners are now recognising that animals may suffer from human conditions such as depression and anxiety.
“Veterinarians are using many human psychotropic drugs such as tricyclic antidepressants and serotonin re-uptake inhibitors, in combination with behavioural modification, to treat these problems in cats and dogs.”
The researchers said clinical depression was difficult to document in animals. To be considered as a diagnosis, the depression needed to have a major, long-term effect on an animal’s behaviour, making it less responsive or less interested in its surroundings.
Depression could occur after the acute phase of a disease or illness and could lead to death. It could also develop in new environments such as kennels, or after separation or death of a companion animal or human companion.
Professor Jones said animal models of depression had been of interest to psychiatrists for more than 20 years, since the human infant response to separation was realised to be similar to other animals.
“Human depression is currently classified in a way that may only be relevant to humans. It is likely to be the broader similarities that can be used in cross-species comparisons,” he said.
Professor Jones said humans and non-human animals showed many similar behavioural states that were called depression.
These included reduction of activity, weight loss, appetite loss, social and sexual deficits, and what appeared to be feelings of helplessness.
There were areas where little was known about the emotional state of depressed animals, even though they looked unhappy. However, scientists could not know what animals were thinking, because of the language barrier. They could not know if an animal had suicidal ideas. Guilt, and feelings of unworthiness common in severe human depression, could not be known in animals.
The drugs used in humans were very effective in animal depression, suggesting that the disturbed physiology was similar.
Grief produced an uncontrollable situation that often led to a passive, depressed reaction and unexpected death in animals. The reaction in humans was similar, but rarely led to deaths.
“The differences between the human and animal responses are not the behavioural aspects, but the thinking ones,” Professor Jones said.
“Whether the emotional states are similar we don’t yet know.”
Media: For further information, contact Associate Professor Judith Blackshaw or Professor Ivor Jones (telephone 07 3365 3311).
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