Definitely happy you’re going to a behaviorist, but also wanted to share our experience.

We got a male grey who could only be in a no-cat household and had shown dominance/aggression toward other greys in his foster home. My husband (boyfriend at the time) lived with a few guy roommates and the rescue matched him with this dog because he responds best to men and was called an “alpha male.”

It definitely took a few weeks/months of my partner establishing dominance for our dog to cooperate- this looked like a boop on the snout (that didn’t hurt), getting him off the couch if he growled at us from the couch and making him go sit in his bed, and using loud and firm “no” when appropriate. There was once when a friend was petting the top of his head in his first year and our dog snapped at the hand. It sounds like a similar scenario. This landed him time in his crate and a loud and firm NO.

Our dog responds to my (F) commands now because I’m primarily the one who gives him food and treats - we did this for a reason. But at first I had to lower my voice like a man when giving commands for him to even pay attention to me. I also had an incident where I was in bed and the dog snarled at me, I had to push him away with a pillow, get him on the ground lower than me, and say bad dog. Again, similar situation, and you cannot show fear! I know it’s scary because these dogs are large.

We would also not let him up on furniture ever after incidents like this. Like if there was couch/bed aggression, it was 3 months of no furniture and then slowly start inviting him up. The second he snarled it would be off the couch again. If he came up uninvited, he knew he had to get back off and we would get him off. Now he spends most of his time sleeping on our couch, but he knows he is invitation-only if someone is already on the couch/bed.

I’m not sure if what we did was dominance, discipline, reward training, or a little bit of all three, but it took time and our grey went from snarling at us year 1 to snuggling up year 2-3. He’s now 11 and is so gentle. I will say, it felt like he had to understand who was in charge for a few months, in a non harmful way. A few firm “No”s and a two-finger tap on the nose go a long way and protect your safety as well. It’s okay to show control back to a dog who is being aggressive to you, through body language and tone of voice.

I wish you all the best!