system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are animal actors selected (auditioned/bred) during/for the audition process?
gpt
Auditioning and breeding are two massively different things, so let's take them separately.

First, an animal breeder selects animals that have certain traits like appearance and intelligence and obedience. Generally the best acting animals had smart parents, and aren't dumb-as-a-post types like poodles or afghans, or hyperactive like irish setters. 

Then training takes place to ensure the animal can follow commands. This can take years. Some individual animals train much better than others so the trainer selects those to put forward for the more challenging roles. 

Finally the audition comes... and the audition is just as much about the handler/trainer as it is about the intelligence and obedience of the animal. Sure you want a gorgeous black horse when filming Black Beauty... but you might need a second no-so-gorgeous-but-smarter-or-gentler horse for some of the closer-in shots such as head-nuzzling an unconscious Aragorn or for the child-actors to ride. And they rely heavily on the reputation of the trainers and handlers to secure this.

So you're often getting a collection of animals for a specific role... and if that doesn't work out, there's always CGI to create those velociraptors or clone a few more for the dalmation puppy horde.