I have a chihuahua also that loves the chickens! He is obsessed with them! He has yet to hurt one and does "herd" them. When I let the chickens and the turkeys free range, he keeps them all away from the woods and tries his best to keep them together. If one gets too far off from the others, he herds them back in with the pack. I dont trust him with the baby chicks, I have seen him snap at them through the fence when they got too close to the outer edges of their pen. But he is obsessed with watching them and making sure they are all ok. I was wondering if chihuahuas werent chicken herders when they were first bred or something! Once, I let him sleep in the adult pen when we saw raccoons out. The adults were all up high roosting and I let him sleep in the nesting box with them that night in hopes he might deter the coons. He didnt mind one bit and it worked - everyone was alive when we got up! Also, when they are free ranging, he is the first to let us know a strange dog has come on the property. We also have a maltese and a german shepherd, but they are not at all interested in the chickens. When the chihuahua raises the alarm, then the shepherd will go and get the other dog to go away. When the chihuahua goes in the pen with the chickens, he kind of stresses them out because he tries to keep everyone in the middle of their yards, so we do our best to keep him out of there. But when free ranging - he has proved to be invaluable!