My senior lab-mix is the sweetest dog on the planet. She has "mothered" adopted kittens, always been cool with any visiting/temporary/permanent animals in the house no matter what kind, will spoon & cuddle with anyone/anything. No food issues, no territorial issues, etc.
Outside she is pretty laid-back as well, wags her tail when she sees other dogs, cats in the yard, etc. But on two occasions across her lifespan she has attacked and killed an unrelated animal. Once about 10 years ago on a hike, she killed a small woodland creature (not sure what it was). And then a few weeks ago, one of our neighbor's chickens hopped the fence into our yard, and she killed it. (We think the chicken was in our yard for at least a day, as the neighbor had found it missing the night before and assumed a wild critter had gotten it.)
So before this happened with the chicken, we were thinking of adopting another dog, a small one. In fact we'd had a chihuahua puppy visit and meet with her, with the kids, etc. and everyone got along fine, even gave both dogs treats and they ate them side by side. But now I am worried. What if....? Of course the puppy would be crated at first, & both trained & socialized together, lots of love to go around, but we wouldn't be on duty 24/7 and the whole idea of a companion pet would be for our old girl to have a companion (she has always been much happier and more active when she has a buddy around).
What does her outside behavior with a non-pet say about her inside behavior with another family animal?
Thanks in advance for any insight.