[ASOC]

herd dogs (cattle dogs) have demonstrated a working vocabulary of up to 1800 words.

https://www.youtube.com/watch?v=6hFMaRFyVSU

https://www.youtube.com/watch?v=tDQw21ntR64

[DallasGal]

My heeler girl, who recently passed, was a very intelligent pup. Easily trained, listened to commands. My coonhound is also smart, but he is lazy :)

[zeugma]

herd dogs (cattle dogs) have demonstrated a working vocabulary of up to 1800 words.

Exactly. If you're going to conduct an experiment like this, you cannot use dogs that have been overbred to imbecility.

I'd definitely want to use some of the obviously more intelligent breeds like working or hunting dogs.