If it was treated like a cone, then yes it would cause lag.
But if I understand correctly, it is an animation, and there is no need for other players to see the dogs in their exact position.
The only thing other players have to know is that there is a dog following you around, and which dog it is.
Unless we want the dogs to interact with each other, and there are so many ways this could be abused
So there is no need to broadcast and serialize the position of the dogs. Hence, no lag.
Christopher, can you provide more details on how you did that? And what changes it makes to the client installation?
I presume that if I join your shard, I will automatically get the necessary new files and Python code?