Holly is a very sweet smart dog (likely either a Blue Heeler/Border Collie mix or a Blue Heeler/Australian Shepherd mix). Holly is approximately 2-years old, 35 lbs, and is full of energy and love. She loves playing with toys and is highly trainable and very smart. She is house trained, crate trained, knows basic commands and a few tricks, and loves people. Though she still has some puppy mischief, she tries hard to please people and enjoys learning. Holly was adopted into a very loving home but after a few months developed issues toward the other dog in the home. Her owners worked with a trainer and behaviorist to try to get Holly past it but after many months of hard work and keeping the dogs separated they decided they could not safely keep her in their home with their other dog. **From her previous owners: She got along great with our other dog for 2-3 months. They played together, slept together, etc. One day out of the blue she became aggressive towards him and never reverted back to being his friend. Our pet trainer thinks something negative happened in her past before we got her, and something triggered that negative memory. We’ve also consulted with vets to try medication in conjunction with training, but it seems she just can’t be secure and comfortable in a multi dog home, at least not with the training that we did with her over the past several months trying to reacquaint her with our other dog. We have split our house in two and the dogs have been living separately.