That’s exactly what my cats and dogs have been telling me for months. The Frenchie is so depressed that the vet has referred him to a canine psychiatrist.
Please don't pay for a canine psychiatrist. If your dog has issues, contact an animal behaviourist. They are cheaper and their results will be seen much sooner, usually within 2 weeks.
If your dog is feeling anxious or stressed, it is generally the result of the home environment and how people treat the dog. The dog should be treated like a dog and not like a human. If you treat a dog like a human it will take over the house, become the leader of the pack (humans will be lower down the pecking order), and start to become aggressive towards strangers, as well as developing separation anxiety whenever it is left alone.
Separation anxiety can show as barking or howling constantly when nobody is home.
Acting aggressively to visitor/ strangers, or even biting people it knows.
Peeing or pooping in the house when it's left alone.
Destroying things when left alone.
The most common reasons dogs develop separation anxiety are (not necessarily in this order):
People let the dog sleep on the human's bed.
People let the dog jump up onto furniture any time it wants.
People let the dog lay or sit on the human.
People feeding the dog before the humans eat.
People saying hi to the dog before they say hi to the owners and other people around it.
In the wild dogs live in packs with a pecking order. There are two dominant dogs, the alpha female and alpha male. These two rule the group by dominating and intimidating lower ranked dogs. It works well in general and the top ranking dogs eat first, sit wherever they like and all the other dogs come to them to say hi. When the alpha dog/s call, the others in the pack come running to them. If we compare this to a dog living in a house with people, the dog is in a pack, just the members of the pack are humans and dogs. The humans need to be the alpha dogs and the dog needs to be at the bottom of the pecking order.
If you let a dog eat before you have dinner, the dog says I am in charge because I eat first. Humans should eat before the dog and the dog should sit there and wait for its turn to eat. If possible, take the dog for a walk before feeding. This simulates the dog hunting for prey and then having a meal. After dinner they usually fall asleep. The walk should be at least 30 minutes long and the dog should be allowed to stop and sniff things, and allowed to run around off lead in a safe dog exercise area.
If you say hi to a dog as soon as you come home from work, you are telling the dog it is the alpha and you are coming to it. When you come home and the dog is jumping up and down and barking and saying pat me, ignore it until the dog settles down. Then let the dog in and call it over to you to say hi to you.
If a dog is barking and howling to get your attention and there is no reason for it to be doing this (no burglars, fires, etc), ignore the dog or growl at it. Tell it to knock it off. If you go over and pat and hug the dog and say "what's wrong with didums", you are simply going to the alpha dog and showing it attention when it calls you.
If you let a dog jump up and lay on you or sleep on you, or sleep on your bed or furniture whenever it wants, you are telling the dog it is in charge of the pack and it can do whatever it likes. Dogs should have their own bed, preferably raised off the ground a few inches to keep them off the cold floor. They should not sleep in the same bed as a human. They should not be allowed to jump up onto the couch and lay on you any time they want. You can call them over and let them sit on the couch with you, but it must be on your terms and the dog should not do it on their own accord.
If you have a dog that is in charge of the house and has separation anxiety, these steps can put the dog in its place at the bottom of the pecking order, in a matter of weeks. The dog will usually continue to act dominantly for the first week but if you continue to be in charge of the dog, then its behaviour will change rapidly, literally over night. The dog will suddenly act depressed and not want to have anything to do with you. However, after 3 or 4 days of this, the dog will suddenly wake up and accept its new position and be a happy dog again and want to come and say hi to you. When this happens you are in charge and most anxiety issues will go away on their own after that.
If the dog has had separation anxiety for a long time, then it might need something like Valium for dogs (prescribed by a vet) to help it chill a bit for the first month. Then it should be weaned off the medication, while you continue to do the aforementioned things.