Context: anime attempts inter-species communication, circa 2014, colorized.
anata jishin mo
inu no kimochi ni natte
hanashi-kakeru あなた自身も犬の気持ちになって話しかける
You yourself too become like the dog's feelings and start talking.
You put yourself in the dog's shoes and start talking to him.
You make yourself feel like a dog and start talking to him.
You make yourself think like a dog and start talking to him.
hanashi kakeru 話しかける
To start talking with someone. (in this case, with the dog.)
inu no kimochi 犬の気持ち
Dog's feelings.
How the dog feels.
How the dog thinks.
The perspective of a dog.
anata jishin mo あなた自身も
You yourself too. You too. (the dog already thinks like a dog, so the point is that you, too, think like a dog.)
sou sureba {inu no
itteiru} koto mo
wakaru toiu
mono desu yo そうすれば犬の言っていることもわかるというものですよ
If [you] do that, the thing [that] {the dog is saying} [you'll] understand.
If you do that, you should be able to understand what the dog is saying.