And even Nintendo Power referred to them as dogs.
Nintendo Power's really not exactly a good source for canonical Pokémon info, though.
I dunno, they're pretty clearly based on big cats. Raikou's a tiger- that's clear as day, and anybody who disputes that is in a certain Egyptian river. Entei looks like a lion to me with the mane and all, and it always seems to be portrayed with a sort of regal bearing, as the lion is associated with royalty.
Suicune's the hardest one to identify, but it's probably a cheetah or leopard to go along with the other two. Think about it- every trio, with the exception of Hoenn's weather trio, are all based on one general idea:
Articuno/Zapdos/Moltres: Birds
Regirock/Regice/Registeel: Golems
Uxie/Mesprit/Azelf: Sprites/fairies/whatever you wanna call them
Dialga/Palkia/Giratina: Dragons
And even Rayquaza and co. are based off of Hebrew mythology (the Leviathan, Behemoth, and Ziz) so I really don't see why Pokémon, with its tendency to patterns, would randomly make two members of a trio based on one thing and the other one on another.
I still call them beasts anyway because it sounds cooler.
Also, adding to the list of things that also bark: prairie dogs.