One of our dogs gets very nervous and howls and pants

Altern wrote:
Beer works every time.

Ha ha - I'd try the beer before medications!

SERIOUSLY, though, before I do meds I'd try the Desensitization Training like Dog Folks recommended above. If that doesn't work try something natural such as Rescue Remedy for dogs--a blend of flower extracts (get at a health food store) or another herbal remedy. I'd use prescription meds as a last resort!