My Molly went deaf early in life. She also went blind. I learned a lot about living with such a person. There's something absolutely wonderful about witnessing the pure courage and fortitude of someone so small and vulnerable to overcome such overwhelming odds. Molly did it and did it so that the world - everyone we interacted with - noticed.
One of the things we did before she went totally blind was train her in movements. I didn't call it sign language or anything so grand - it was just how Molly & I communicated. For instance, she knew that when I was going to pick her up, I sort of bounced her on her hind legs three times before I actually picked her up. That way, she could ready her muscles and not get hurt when I picked her up. Another example is when I'd put three fingers on her chest, my thumb and pinky finger under her arms and sort of push forward, she knew that it was time to "wave" to whomever was in front of her (she also knew this would probably get her a treat, because it was just so darned cute!).
Coming from this background, it was very interesting to me to find that there's a person who's developed ASL: Animal Sign Language. She did it so people and dogs could communicate more clearly with each other - not just have the dog do the person's bidding - they exchange information. They share where it hurts, that they want water, food, or treats, or a specific toy. That's HUGE!
That's an important step to humans understanding that they don't actually "own" their dog/cat/horse/animal any more than the people of the South "owned" their slaves. It's not possible. It's only through gross lunacy and an immoral sense of superiority that such an absurdity could happen. It's absolutely beyond me how any human could fathom that they could "own" another life.