[melaniejs (OP)]

John asks:

"Dogs come in all sizes, from tiny Chihuahuas to giant Great Danes. Their head size is hugely different, as must be their brain size. Does this mean that a Great Dane is massively more intelligent than a Chihuahua?"

We're looking into this for the show, what do people think?

[alancalverd]

You have to define intelligence, then determine how you would measure it in a dog.

Problem is that the huge spread of sizes results from selective breeding for particular characteristics, so your measure of intelligence may turn out to be characteristic of a breed other than its size. There is  no doubt that even among similar breeds there is a great variance in trainability. The golden retriever is a modern derivative of the flatcoated retriever and generally considered more trainable (e.g. as a guide dog) than a pure flatcoat, though in my experience the flattie is a more natural retriever "if he is in the mood". 

Are collies intelligent, or just natural  pack hunters that respond to a human "alpha"?

Circus dogs tend to be Jack Russell size. But are they selected for innate intelligence or long working life and small appetite?

There's a family tale of extreme hunting dogs (IIRC Borzois) being so intent on following a scent trail that they crashed into trees and knocked themselves out. Working out which way a deer has run is one kind of intelligence, running through a forest is quite another.

The best story I heard was from an army dog trainer. Asked to supply search and rescue dogs to support the Polish police after an earthquake,  he said it was quicker to teach the dogs (German Shepherds) Polish commands than to teach the cops English. Clever dog, or expert teacher?

[Bored chemist]

Are big dogs more intelligent than small dogs?
Apparently, yes.

https://link.springer.com/article/10.1007%2Fs10071-018-01234-1

Is it just me who thinks it's funny thet the publisher is "Springer"?

[melaniejs (OP)]

Thanks for your contributions!

We answered this question as part of our last show, and interviewed the author of the paper you found!

Listen here:

https://www.thenakedscientists.com/podcasts/question-week/are-big-dogs-smarter-small-dogs

Enjoy,
Melanie