Casting

Casting of film roles can be the subject of debate. I read this long article about some humans being disappointed that white humans are cast in roles as non-white humans. It was somewhat interesting. It did not say anything about dogs, though. It is common knowledge, at least among dogs, that Lassie was mostly played by male dogs, despite being a bitch. Why was this not interesting enough in the scope of the article? I guess it is the normal focus on humans. Isn't this pure focus on humans interesting, when the article is about diversity? Where is the species diversity? It is not that I am complaining, but it would be interesting to know if this pure focus on humans was intentional or not. I guess It was unintentional, but I do not think I will ever know.