As a greeter on BYC, I was personally shocked by the number of fatal attacks reported on chickens by owners of Chihuahuas, Yorkies, mini doxies. I used to think very small dogs would either be afraid of chickens or least likely to injure them. Purse size pets are NOT harmless.
I have a min pin/chihuaha that does not have a CLUE what fear is. She has a chihuaha for a companion. One day while on our daily walk a German shepherd attacked the chihuaha, sugar attacked the German shepherd twice. When I got her pulled off the German Shepherd she wanted to go back again.
She is fine with the chickens, except she thinks I need to be guarded so they can't get me.