Help with new adult dog!

This might get long winded so sorry in advance.
We just adopted a shelter dog (small poodle mix) about 5 days ago who was found as a stray, so very little is known about him. He's between 4-7 they said. Still has stitches in from being neutered. However, his hair is matted and he has bad teeth and gums, so I imagine whatever situation he was in was not that great. I'm starting to think that maybe he was a stray for awhile.

The first day with him was fine mostly. I expected this, since there's a "honeydog" period. He slept, he chased a ball and he didn't bark at all. Then the third day, we took him to petco, where he did well around other dogs and the people there, but he peed inside there. That same day he peed inside our apartment (that was the only time he has done it so far).
Then the landlord came for rent. That's when we found out he does not like strangers coming to the door. He bit his pant leg, growled and didn't like him. Our landlord came back a second time a little later and he sniffed him out and growled a little. He was fine as he was leaving. Our landlord is giving us a chance to get him settled, but now we are worried.
Then our neighbor came over and growled at her. She moved some kind of way and he jumped on her, but didn't bite her. My husband told him to go lay down and he listened and he knew he did something bad. Then he sneaked back and growled at her.
Now he is starting to bark at every little noise sometimes. Especially when he's with my husband and sometimes with me. When we walk outside, he barks if he sees neighbors outside. He barks when I come home from work. He barks in his crate and outside his crate. He's starting to bark overnight at things.
The only thing he doesn't care about are other dogs.

On the other side of things, he seemed to already know how to sit. It took a day to teach him to learn "lay down" and "belly rub". So, I think he can learn things. He pays close attention to us and looks at us a lot. For example, when we go for a walk, he is good at paying attention to us. He stops at corners and walks nice.

We have no idea how to control the barking. His barks range from these little woofs under his breath and growls to barking loudly depending on what he's barking at. And in people's opinions, is the aggression issue with visitors not going to change? I really want to try something without a behaviorist.

He seems to bark more after I leave for work and my husband comes home. Then when I get home he goes nuts and it continues when I go to bed and he's in his crate. He does this thing where he makes low woofs a few times then yowls at every noise and sometimes it seems to be at nothing.

Last night it got so bad my husband made him come to bed with us. He didn't do it as much, but he still did a little. Especially around 4am, when the neighbors were moving around going to work. Then when my husband put him back in his crate this morning and left he hasn't made a peep since, even though there has been tons of noises. If someone came to the door he would freak out though.

Can a dog be afraid of the dark?

I doubt he's afraid of the dark but it's generally quieter at night so he'll notice sounds more and react to them. I'd put a baby gate up to stop him accessing the front door too until he can be trusted around visitors.

For some reason though, it seems like he's more alert at night time. During the day, he sleeps so hard he snores. I try to get him to be active so he sleeps later in the day...but he never wants to play with toys.

I'm going to list out a couple of things I would do if this were me, and maybe you can try a few of these or just ignore them if you think it won't make a difference. I've fostered a lot of dogs in my apartment, so I also can't have dogs barking, growling at people, etc.

- remember everything is new to him so give him some time
- go for a long walk at least once a day for at least 45 minutes so he's getting some exercise and will be tired (longer if possible)
- also go for a 2nd shorter walk at some point, half-hour or so. Exercise makes such a big difference.
- keep a leash on him when you're home so you can keep him under control and distract him when he barks. I use a calm "no" and then re-direct with treats to get the dog to sit quietly and reward that behavior
- is he quiet in the kennel? Then keep him in there at night, maybe with a fan on or soft tv noise to drown out some outside noise
- feed him all his meals in puzzle-type toys or in little training sessions so he's working his mind

Hope that gives you some ideas! I know the barking can be frustrating. He's probably a little scared.

I did write this post about stopping a dog from barking in the yard. Not exactly the same problem you're having, but some of the concepts are similar: https://www.dogids.com/blog/how-to-s...g-in-the-yard/

Thanks for the help.

His barking is hard to pinpoint. He barks at sounds, but also (like when he's in the pen) it seems like he's barking at nothing. Possibly barking because he wants to be let out and be with us in bed. However, I've tried moving the pen in our room and he still barked and growled.

My husband needed sleep really bad so he did something bad and let him sleep with us. He still barked at noises.

We called a behaviorist to come. We are going to see what happens. He has an issue with visitors too and he barks and growls at neighbors. So I think he's scared.