Do you have any tips for crate training? I have tried his fav toys, treats and,things to occupy his time and all he cares about is being put in the crate. Is there anything I can do to make him like the crate?
If the dog has suddenly started doing this you have obviously changed something you are doing: schedule, sleep, exercise, chang of food, a pet that is no longer in the house...
I completely disagree with muzzling and spraying stuff at the dog. Distractions, like toys, typically don't work for very long.
Do you walk your dog or do you just let it run wild on your land for exericse? It matters because you have to do things that show you are in charge. A controlled walk on a short leash for about 20-30 minutes just before you leave the house should be done to get the energy out of him.
If the dog has separation anxiety you can break him of this by practicing leaving the house. As you leave the house you have the dog sitting there watching you leave. Do everything as you normally would if you were leaving. If you rattle your keys or get your purse, do those things as if you were really leaving. Don't pet the dog or give it any sort of attention. Leave for about 10 seconds then come back in. If the dog behaves, give him praise or even a treat (although treats aren't really necessary). If not, ignore him. Then extend the leaves to longer and longer periods. You may have to practice this exercise for a long time (could be days or weeks) until the dog realizes that leaving is not a bad thing.
But exercise just before you leave may also prove to be very important.
I know this seems like a lot but dogs require a lot of work to break them of bad habits and obsessions. This sort of behavior
could lead to aggression if you don't get it under control.