Hi there, my name is XXXXX XXXXX I am a registered veterinarian and I would like to try to help you.
Separation anxiety can be difficult to help with but there are some simple steps that you can use to improve your situation.
The most important thing is to vary the routine you have before you leave so your dog doesn't predict (and become stressed) before you go. If you wake up, have breakfast, go for a walk, pick up keys and leave, eventually your dog is stressed by breakfast and it is impossible to keep a dog calm when you are gone if he is stressed even before you leave.
Leaving a radio on (spoken is best), and leaving a distraction toy (kongs stuffed with peanut butter are great) can really help. Vary this up also since this will form a routine before you leave.
Try and leave for a few short periods so your dog can't predict when you will come home.
Give lots of attention when you arrive home.
DAP collars can be useful as well as DAP diffusers. These have natural pheromones which can reassure your dog and help reduce stress. You can get them online without prescription.
These are the basics of dealing with separation anxiety.
I would recommend doing all of these things before considering medications.
I hope this helps you?
The citronella collars are really detrimental and could be causing the worsening of the problem.
Your dog is anxious because you have left and then anxious because of the collar. This can escalate quickly into a really uncontrolled situation (which it sounds like you have). I would definitely recommend stopping the use of this collar. I believe they are quite inhumane and have no place in training.
I would recommend starting back at square 1 again and re-jigging your routine.
Stick with it and hopefully the situation improves. Unfortunately for very severe cases, it may not be possible to ever completely solve the problem.
If you need anything else, just reply.