Sydney Veterinary School: Size matters for dog's behaviour

20 January 2014

A variation of Short Man’s syndrome applies to man’s best friend, new evidence from the University of Sydney suggests.

Sydney Veterinary School
Study at Sydney Veterinary School

The shorter the dog, regardless of breed, the more likely it is to march to the beat of its own drum, according to the University of Sydney-led research on the relationship between a dog’s shape and its behaviour.
“There will always be exceptions but these data on large numbers of dogs help to define a ‘new normal.’ What is normal in terms of dog behaviour clearly depends on more than simply its breed,” said Professor Paul McGreevy from the university’s Faculty of Veterinary Science. Professor McGreevy is lead author of a journal article on the findings published in PLOS ONE recently.
“The most comprehensive study undertaken to date, our research shows that certain physical characteristics in dogs are consistently associated with certain types of behaviour. Essentially, the shorter the dogs the less controllable their behaviour is for their owners.”
The study used owners’ reports on the behaviour of more than 8,000 dogs from across 80 breeds and related them to the shape of 960 dogs of those breeds, revealing strong relationships between height, body weight, skull proportions (relative width and length) and behaviour.
The study discovered that 33 out of 36 undesirable behaviours considered were associated with height, body weight and skull shape.
For example, as a breed’s average height decreased, the likelihood of behaviors such as mounting humans or objects, owner-directed aggression, begging for food and attention-seeking increased.
“The only behavioral trait associated with increasing height was ‘trainability.’ When average body weight decreased, excitability and hyperactivity increased,” said Professor McGreevy.
“The ratio of skull width to length was an interesting case. Long-skulled dogs—such as Afghans, salukis and whippets—appear to be a product of selection for hunting/chasing characteristics as they excelled on those indicators.
“According to owners’ reports, they flunked on fear of strangers, barking persistently, and stealing food. Given hunting dogs have not traditionally been companion animals sharing close quarters with humans, this may not be surprising.”
In contrast, the results confirmed short-skulled dogs, such as pugs and boxers, the result of generations of selective breeding, retain some “puppyish” characteristics as adults but have lost many of their hunting traits entirely.
“Undesirable behaviours such as owner aggression, or mounting, occur more often among small dogs. This suggests that, in small dogs, these behaviours are tolerated more than they would be in larger dogs where such behaviours are more unwelcome and even dangerous. Equally, such behaviours in small dogs may be a result of their being overindulged and overprotected,” said the Sydney Veterinary School professor.
“These findings will interest dog owners, breeders, veterinarians and evolutionary biologists. They remind us that domestic dogs are an extremely useful model for exploring the biological forces that produce diverse animal structures and their related behaviours.
The latest report follows previous studies by the same group that showed dogs’ eye and brain structure depends on skull shape and that skull shape depends on sex.
“The interaction of nature and nurture in producing the relationships we have described in this study creates a raft of fascinating questions that further studies will address.”
Proposed Doctor of Veterinary Medicine at Sydney Veterinary School
The University of Sydney has offered a five-year, Bachelor of Veterinary Science in past years. The university is now transitioning its vet program from a Bachelor of Veterinary Science to a Doctor of Veterinary Medicine program. In 2013, the Sydney Veterinary School offered its last Bachelor of Veterinary Science intake. In 2015, it is planned that the faculty will offer a four-year, graduate-entry Doctor of Veterinary Medicine degree.
OzTREKK will post information regarding the new DVM program as soon as it is received from the University of Sydney Veterinary School.

Learn more about the Sydney Veterinary School and about Australian Veterinary Schools.

Do you have questions about Sydney Veterinary School and about studying veterinary programs at Australian universities? Contact OzTREKK’s Australian Veterinary Schools Officer Rachel Brady by emailing or by calling 1 866-698-7355 (toll free in Canada).