the welsh springer spaniel is the most uncommon breed in the us
dingo
bulldog
There is not a specific dog breed that is smarter than any other dog breed in the world than there is in the USA, but the smartest dog breed are poodles.
On the dog show, the Beagle 'Aro' was the symbol to the most popular breed in 2007, as well in 2008.
In the US, Dachshunds have bitten the most, followed by Chihuahuas and Jack Russell Terriers.
The US.
We can't answer your question, because you do not give us a breed of dog. Please restate your question
grey hound
grey hound
500,000 to 1,000,000
yorkie
Labrador Retriever