I have been thinking about your predicament. I do think your husband has some kind of challenge where he is controlling and possessive. I don't think you noticed it as much because he put you in his world and kept you near him like he is doing with this dog. You mentioned that you felt like "we are best friends" until you experienced this behavior of his with this dog.

He may be on the autism spectrum, however he may also have OCD too. From what you have shared he struggles with his sense of "control" and that tends to be a challenge with both the conditions I posted, though I am not an expert and am not diagnosing him. But you shared how he is really smart and his mind tends to go fast and he can struggle with that. It sounds like he struggles with sharing or if others challenge him in someway when it comes to business or perhaps a job etc, but this could be due to his need to feel a sense of control of his own world too. As eskie put it, "how his brain is wired" that can seem toxic and abusive and even narcissistic. It's quite possible that he is not intentionally trying to be abusive towards you, but, he needs to have full control of that dog to feel comfortable in HIS mind with it where he can control everything about how that dog is a part of HIS world. This is what makes me think of OCD because that's a challenge where the individual needs to have everything in a certain place to "feel" safe with whatever they have in their world. I read at one point that Howard Hughs had OCD. He was VERY controlling and eccentric and difficult to get along with due to his obsessive need to control and had a busy mind.

I think one of the reasons you can't find anything doing a Google search is you would have to search the kind of challenge that comes with how his brain is wired. Once you find that a lot of things will make sense to you. You are probably searching if men are possessive with dogs. Instead you need to maybe search OCD symptoms or the symptoms that present with someone with ASD.

My husband has ADHD and Dyslexia, I have learned about these challenges and when I read about them as I mentioned, a lot of things began to click as my husband would present me with these same behaviors as is described.

If you discover what makes him tick that is when you need to decide IF his challenges are something you can live with because he really won't change all that much and that is what you are noticing in this particular situation. His own mother has noticed he is different, mentioned what it might be, however he would have to see a professional in order to get diagnosed and possibly get help to manage his condition.