I'm interested in the growling and what your trainer says. Why would Boi be growling at your DH?
I have some theories but none explain 100%.
1) When he gets home, Baymax barks once. She starts it! Then DS5 runs to the door shrieking, "Daddy's home!!!!". The energy gets so high right before he walks in the door, and is generally much higher when he is home.
2) Teenage fear period. He was fearful of DH for a couple weeks. DH injured a rib which affected his gait. He was changing into camo hunting clothes and later blaze orange - which change his shape and smell. He goofs off with the kids using different voices and accents. All those were triggering fear behaviors in Boi. He is not acting fearful anymore. Edited- he is not acting fearful all the time around DH now. Every once in a while, like once a week he will get a little cautious/startled.
3) Becoming protective of me and the house? This would be disastrous, and this possibility is why we neutered him a year earlier than I had planned.
4) Teenage jerk phase. Maybe its this, he's trying to figure out what gets reactions and found something that works.
IDK. Now he is barking when I get home too. I am not happy with his barking.
The answers would be
1) train settle and desensitize.
2) gently encourage confidence with high value rewards + exposure
3) immediate firm corrections that dont come from me, and his behavior results in losing access to me
4) leash corrections and spatial corrections that come from me, as firm as necessary to get avoidance or submissive body language. That sounds bad in writing - I'm talking about shifting his body weight or changing where he is looking.
But if I'm wrong about what causes it, the wrong response would make it worse! Thats why I'm stuck. I'm afraid of making it worse.
I think the best way forward will be watching his body language each time to pick which response is appropriate at the time. Thats intimidating. I just dont want to mess it up.