How does one dog breed recognise another?
If you look at a Great Dane and then you look at a Chihuahua, they are so different. Do we know if a Great Dane meeting a Chihuahua recognises it as another dog?
Hannah Laeverenz Schlogelhofer put this question to Dr Charlotte Duranton who specialises in dog behaviour, and Professor Donald Broom from Cambridge University...
Charlotte - When you interact with another individual it is essential to be able to identify them, and to know if they belong to your own species or not, so you can adjust your behaviour accordingly. Usually, physical criteria can be used as for most animal species, all individuals are similar in shapes, sizes, proportion, or colour.
But dogs are different. They are the first domesticated species, and have lived in a human environment for at least 15,000 years. During this time we have selected them for different purposes, through artificial selection, which has led to all of the different breeds we know today.
Hannah - So this is how we end up with dogs the shape of sausages meeting dogs that look like bears. But do they recognise each other as the same species?
Charlotte - It is known that dogs use different ways to identify each other as dogs and to communicate together: auditory communication with sounds (such as growls, or barks), chemical communication with odours, and visual communication with for example body position, or face recognition.
Hannah - Smell is the most important of these canine senses. Donald Broom, Professor of Animal Welfare at the Department of Veterinary Medicine at the University of Cambridge, supplied us with this answer...
Donald - When large dogs, such as Great Danes, encounter very small dogs they approach them and sniff them as they would to a larger dog. They must recognise them visually as dogs to approach in the way that they do but the conclusive evidence for being a dog is their smell. Every dog is distinguishable from other species by its characteristic smell and every dog has an odour that allows it to be recognised as an individual. These odours are not dependent on body size, little dogs are treated as dogs, not as small animal prey to chase.
Hannah - Well that’s a relief for the more rabbit sized dogs out there. But this is also important for mating.
Donald - The most obvious test of species identification can be seen if there is a possibility of mating. Bitches on heat respond to approaches by male dogs, whatever the size difference. Big male dogs go through the courtship procedure with small dogs that are on heat and small male dogs show interest in large bitches on heat, even if they can't normally reach to mate. However, the small dogs may show more fear behaviour, if approached by an unfamiliar large dog, than they would to a dog of their own size.