Dogs that have a positive outlook on life tend to cope better with being left alone than their more pessimistic counterparts, new research from the UK's Bristol University reveals. The findings are published in the journal Current Biology. 'We know that people's emotional states affect their judgements and that happy people are more likely to judge an ambiguous situation positively,' explained Professor Mike Mendl of Bristol University's School of Clinical Veterinary Science. 'What our study has shown is that this applies similarly to dogs - that a "glass-half-full" dog is less likely to be anxious when left alone than one with a more "pessimistic" nature.' The results shed new light on the emotions of man's best friend. They could also aid in the identification of dogs that are particularly prone to separation anxiety and help animal shelters find the right owners for them. According to the team, half of the 10 million pet dogs in the UK may perform undesirable separation-related behaviour (SRB), such as barking, going to the toilet and destroying their owners' things, at some point in their lives. In a small number of cases, owners seek professional help to stop their dogs from engaging in these behaviours. However, many owners simply dismiss the behaviour and assume that their dogs are fine or even happy, while some may eventually decide to give up the dog. Professor Mendl and his colleagues carried out some simple experiments on 24 dogs that had recently arrived at 2 animal shelters in the UK. First, each animal was tested for separation anxiety-related behaviours. A researcher interacted with each dog in an isolated room for 20 minutes. On the following day, the dog was taken back to the room by the researcher. After interacting with the dog briefly, the researcher left the room for five minutes. The dog's response to this separation was filmed and an SRB score calculated for the dog. The next part of the study saw the researchers gauge the dogs' mood. To do this, the animals were taught that when a bowl was placed at one location in the room, it would contain food - this was the 'positive' position. Meanwhile the animals learnt that a bowl placed at another location (the 'negative' position) would be empty. Once the dogs had been trained, the scientists placed a bowl in an ambiguous location midway between the positive and negative positions. Dogs that ran quickly to this bowl, as if they expected it to contain a tasty morsel, were classed as being 'optimistic', while dogs that moved more slowly towards the bowl were classed as 'pessimistic'. Finally, the team investigated whether there was a link between a dog's SRB score and its attitude towards the ambiguously-placed bowl. The results were clear: dogs that were classed as optimists displayed the lowest levels of anxiety-like behaviours when left alone for a short time. In contrast, dogs that responded badly to being left alone were more likely to make pessimistic judgements when faced with the ambiguously-placed bowl. 'Many dogs are relinquished each year because they show separation-related behaviour,' commented Dr Samantha Gaines of the UK's RSPCA (Royal Society for the Prevention of Cruelty to Animals), which co-funded the research. 'Some owners think that dogs showing anxious behaviour in response to separation are fine, and do not seek treatment for their pets. This research suggests that at least some of these dogs may have underlying negative emotional states, and owners are encouraged to seek treatment to enhance the welfare of their dogs and minimise the need to relinquish their pet. Some dogs may also be more prone to develop these behaviours, and should be re-homed with appropriate owners.'