My large dog chews due to separation anxiety. What can I give him?

Sorry to hear that Bo is having this issue. Thank you for rescuing him :)

Separation anxiety is a huge issue in dogs and it is not an easy fix even with medications. We cannot recommend you give any medications without you talking to your vet first, especially a drug like alprazolam that is a controlled substance. What I can tell you though is that 0.25mg will not touch a dog that size. Dogs take a MUCH higher dose than humans as they metabolize the drug differently.

What you really need to do is try to correct the behavior instead of trying to mask it. I suggest you consult a dog trainer in your area that will come to your home and assess the situation. They can help you try and correct the behavior. Sometimes medications are indicated to be used in conjunction with training and then you can try to wean them off the drugs eventually. You will need to work with your vet and trainer about using medications in conjunction with behavioral modification. Clomicalm is one of the main drugs we use for separation anxiety in dogs.

https://www.veterinarypartner.com/Content.plx?P=A&S=0&C=0&A=3144

I recommend Bark Busters for a training company:

http://www.barkbusters.com/dog-training-columbia-sc

Of course you can do your own research for trainers in your area.

Hope this helps. Best wishes.