★★★★★
Per Journal of Vet. Med. Science: "GABA dosage of 30 mg/kg of body weight once per day" will alleviate stress/anxiety without 'side effects'. This study was performed on aged dogs, 15+yrs., to calm them for vet visits.
Personally, I would lessen the dose as I am familiar with GABA's human use. My 10lb. dog would use 136mgs. per above dosage, however, I would start with half & this depends on the stress level. Example: for humans, mild stress dose is 100mgs., 3 x's per day. Severe stress is 250mgs., 3 x's per day per 'PharmaGaba' mfgr. GABA is avail at most health food stores. It's effects are similar to valium, however, mild. I would purchase the capsuled powder & break open the cap. to sprinkle in water or food. Buy the lower dosage if avail to make it easier to dose. GABA is a amino acid derivative & the human brain has GABA receptors, however, I don't know about canines.
Last note: I have an animal feed store nearby which does have "calming" supplements for various animals such as horses, dogs, etc. The price is inexpensive compared to the human stores. Read the ingredients & research them online.