Separation Anxiety
Work on your dog's confidence and independence by asking them to sit before they get fed, go outside, get pet, etc. This will help build their confidence. You can then start to work on independence training. Ask your dog to sit and then stay on a mat or bed or "place" and start increased distance away from your pet. Eventually, you should be able to go to another room while they can't see you but are comfortable in the room.
Departures:
Before you leave, give your pet a high value treat or toy and ignore them for a few minutes before your departure. This helps create a positive association with your departure.
Try to leave quietly without gathering keys, purse, bag, wallet, coat, etc that may be a trigger for your pup. As hard as it is, do not make a big fuss of a good-bye.
Start with short amounts of time (ex: a few minutes) you are gone. This helps your pet realize you are not always gone for extended amounts of times.
Returning:
This is the hardest part! Ignore your pet for a few minutes when you arrive home. This helps reinforce it is not a big deal when you leave or return. When they are calm and quiet, you can greet them in a calm and relaxed to manner to reward them with positive reinforcement.
Supplements:
VetriScience Composure
This is a calming treat that has proteins in that are relaxing and may cause a little sleepiness. It works within 30 minutes and lasts for about 4 hours.
https://www.chewy.com/vetriscience-composure-chicken-liver/dp/42645
Zylkene
Calming milk protein that gives dog a sense of comfort and relaxation. This can also be given as needed but may work better if given every day.
https://www.chewy.com/vetoquinol-zylkene-capsules-calming/dp/121055
Solliquin
This is a calming blend of tryptophan and L-theanine that relax a dog. This is also better if given every day.
https://www.chewy.com/nutramax-solliquin-soft-chews-calming/dp/185266
Pheromones: Dog Appeasing Pheromone
A calming pheromone (hormone) we can smell but out dogs can’t. A similar hormone that mommas release when they are nursing their pups. It comes in from of Adaptil Collar or spray or diffuser.
Be careful with triggers like a bright/loud t.v. Turn off the tv when you leave and have Through A Dog's Ear playing in youtube or Calm Dog Music on Pandora. These are shown to calm a dog’s heart rate down.
Resources:
websites
https://www.aspca.org/pet-care/dog-care/common-dog-behavior-issues/separation-anxietyhttps://malenademartini.com/for-owners/separation-anxiety-training-programs/books
https://www.dogwise.com/ebook-separation-anxiety-in-dogs-next-generation-treatment-protocols-and-practices/https://www.patriciamcconnell.com/store/product/i-ll-be-home-soon