<human>: Can you condense the text into three sentences or less?

My wife and I adopted Russel (the afformentioned beagle/JR mix) about six or seven months ago from a local APL. He is currently 1 yr.

He is a very loving dog but came with some issues and very little backstory. At first when we would leave our apartment he would bark like a madman. So much so that the apartment complex gave us a warning. So we got him a bark collar and that stopped. 

When we confined him to a cage during alone time, he would mess in it an roll in it. After shortening the cage (it was a little too big) it became less frequent but would still happen. 

We then tried confining him to the bathroom and he scratched the door to hell and peed on the floor consitantly.

At the advice of our friends, we purchased two baby gates ( he is easily able to leap one). First he dug at the walls, and then realized he could barrel through the bottom one. The ripping of the gate off the wall does damage the walls. 

This weekend we tried leashing him in the garage (its heated and no chemicals on the floor. We did take precautions to keep him safe). When we returned from our movie and opened the door, he was sitting by the door off his leash... he chewed through the leash to break free.

Another hound owner told us to let him have reign, just close the doors etc. Well he got into the trash and shredded a whole box of tissues.

We both love this dog and just want him to not panic when we leave. He is a very clingy dog naturally (did know this for a while) and we are trying to ween him from constantly being up our butts.
<bot>: our dog has separation anxiety and is always up our butts. when left alone gets some wicked (pardon the nonPC) tard strength.