Australian Cattle Dogs and other Animals
The Australian Cattle Dog is a Herding Breed. The herding instinct is merely a modified (ie, controlled) prey drive.
Keeping this in mind, one must approach the subject of the cohabitation of Australian Cattle Dogs and other animals with great caution.
Most Australian Cattle Dogs are pre-wired to chase things that move fast and nip at them. This is instinctual, it's not a learned trait. The urge to "heel" a fast moving thing (be it another animal or a bicycle) can be curbed and can be diverted but it cannot be totally extinguished. Most other small companion animals are small and they move fast. Caution need to be taken during training, especially with a young dog. While an ACD nip is non-injurious to the bovines they were bred to heel, a nip on the "heels" of a cat or a bunny could lead to serious injury.
The best way to deal with a multi-pet household that includes a Cattle Dog is to make sure that the other animal always has a way to get away from the pursuit of the dog. Many people use baby gates to partition off rooms or prop door ajar with an opening wide enough for said "other animal" to run through but that won't allow entry to the chasing Australian Cattle Dog.
If baby gates in your doorways are too much of a contrast for your decor you may want to try either cutting small holes in your interior doors or providing special furniture for "escape" purposes. Several companies provide special doorway kits and kitty perches that make suitable retreats. I'll provide some links here in the near future.
With smaller animals (cats, ferrets, reptiles, rabbits, hamsters, birds, etc.) the key thing is TRAINING your Australian Cattle Dog that chasing and nipping said animal is completely unacceptable. Even puppies that chase just in play can harm a smaller animal accidentally. Obviously overriding the heeling instinct in a Cattle Dog takes a LOT of diligence.
Until you are 100% sure that your ACD will not actually harm other smaller animals you would be wise not to EVER leave them alone unattended....not even for a minute.
There are also other, larger companion animals that many people live with. With horses and goats and other livestock the Australian Cattle Dog also needs to be "watched". This breed is NOT an appropriate livestock guardian. If put out in the pasture to "guard" goats or sheep you will likely come home to exhausted animals that have been moved all day from one side of the field to another.