Ayesha Azeem ‘23

For centuries, humans have been breeding domestic dogs with the intention of producing specific skill sets needed to improve humans’ lives. For example, purpose-bred dogs can be used for hunting or as service dogs that guide people with disabilities. Dog breeding has been highly controversial lately, since dogs are now seen more as companions rather than workers. In a new study conducted by Erin E. Hecht of Harvard University and team, including Professor Jeroen B. Smaers of Stony Brook University, the researchers found that selective breeding has altered dogs’ brains more than ever expected.

Though significant breed differences are obvious in behavior, trainability and temperability, surprisingly, neural differences had not been observed before Hecht’s study. Hecht examined MRI scans of 62 purebred and domestic male and female dogs of 33 breeds. The dogs studied were referred for neurological examination but did not have any abnormalities. The MRI images were collected at the Veterinary Teaching Hospital at the University of Georgia. Before concluding the study, the scans were re-reviewed and approved by a veterinary neurologist. 

Rather than simply studying brain size or skull shape, the researchers also focused on specific networks in the brain that differ significantly among the individuals. The researchers studied the regions of the brain involved in the mesolimbic reward system, olfaction and gustation, vision and motor movement, social interaction, and stress and anxiety. After reviewing the MRI scans extensively, the team concluded that significant variation exists in brain morphology of dogs. They additionally discovered that though larger dogs tend to have larger brains, there is high variability in the brain to body ratio in different breeds. The networks studied in the MRI scans varied across breeds, possibly due to skull morphology as observed in the study. The changes seen in different networks lead to behavioral differences. For example, dogs bred for hunting purposes have brain regions that support higher-order scent processing. 

Though show animals are still selectively bred, most dogs are kept instead as companions and house pets. This study may be used as further support for those against selective breeding, since differences are not only seen in behavior, but in neural networks as well, implying a more permanent change than believed prior. 

References:

1. E. Hecht, et al., Significant neuroanatomical variation among domestic dog breeds. Journal of Neuroscience, (2019). doi: 10.1523/JNEUROSCI.0303-19.2019
2. https://news.stonybrook.edu/facultystaff/study-shows-breeding-has-altered-dogs-brains/
3. Image retrieved from: https://upload.wikimedia.org/wikipedia/commons/0/06/Askals_or_aspins_are_mongrel_dogs_in_the_Philippines.jpg