PET TIPS: Are bigger dogs smarter?

Pardon the pun, but this one seems like a no-brainer.

In biology, there has long been a belief that larger brains are superior to smaller ones – presumably because they have room to store more data.

But it doesn’t always follow that any animal who is big is automatically smart. Sure, we can point to the extreme intelligence of elephants and whales. But there were also enormous dinosaurs who had tiny brains – basically they were gigantic but dumb lizards.

So when we’re comparing different species, it’s not enough just to look at overall size. We have to take into account that an elephant, for example, is a mammal, and thus has a much more highly developed brain than a reptile.

But what about differences between animals of the same species? Dogs are unique in having an almost infinite variation in size and shape, despite genetically belonging to just one species. So, should we expect that they would all have a similar level of intelligence, regardless of body size?

A new study in the journal Animal Cognition has examined that question, and the results are in: It turns out that bigger dogs, who have bigger brains, do indeed appear to be smarter than smaller dogs – at least, when it comes to certain types of behaviors known as “executive functions.”

For this study, researchers used data from the citizen-science website, which allows pet owners to test their dogs and submit the results. The database now includes more than 7,000 purebred dogs representing 74 breeds.

Researchers looked at two specified “executive function” tests. In the short-term memory assessment, dogs had to be able to recall which plastic cup their owner had hidden a treat under. And in the self-control test, dogs were evaluated according to how long they could resist taking a treat they were told not to touch.

In general, the smaller dogs had more difficulty than the larger dogs in locating the hidden treat under the correct plastic cup. The smaller dogs were also unable to wait as long as the bigger ones before stealing a forbidden treat.

The researchers controlled for obedience training as a variable, so they were able to show that the behavioral differences between the smaller and larger dogs were not related to the fact that big dogs are more likely to have had formal training.

The study’s authors, who work at the University of Arizona’s Canine Cognition Center, said the size difference was only apparent when they looked at executive function, but not other types of behaviors. For example, dogs of all sizes did equally well on measures of social intelligence, such as being able to follow human pointing gestures.

For the next step in their investigations, the researchers want to look at size differences within the same breed. For instance, miniature poodles and standard poodles are genetically almost the same, except for their size. How much of a difference will it make that the standard poodles have bigger brains?

And what, if anything, does this research mean for pet owners? Would you ever (or did you already) reject the idea of adopting a small dog because you thought it wouldn’t be as trainable as a larger dog?

I confess that in my case, the answer is yes. I wanted to win obedience competitions, and I knew it would be a much more difficult challenge if I had, say, a Chihuahua. I took the easy way out and got a Sheltie. In fact, a larger-than-normal Sheltie, with enough room inside her skull for a substantial brain.

Because this recent study doesn’t really break new ground – it just confirms what dog trainers have observed anecdotally for decades.

Debbie Gilbert has been handling dogs for 50 years and won numerous AKC obedience competitions with her late Sheltie, Sunny. She lives with her current Sheltie, Daisy. E-mail your Pet Tips questions to

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