Take him to the vet. See if something is wrong. How much exercise is he getting? Tired dogs aren't as reactive.
Are there some good , positive obedience classes you can go to ? Barring any medical reason he might just be feeling very insecure. Changing homes at this time in his life is probably very confusing and scary. Classes will help build trust and a trainer can give you advice. Just dont use punishment like loud noises and spray bottles. If its insecurity, it will just make it worse. Distractions like doing tricks etc, will likely be better.
My corgi is a barker! I adore this dog, but, oh! that corgi bark! Pierces right through your head. At least beagles sing.
When I adopted my Corgi he also barked at everything. I only knew he had been in the Shelter several times as a stray and thus surmised he had not been much of a house dog, so everything was new to him and set him off. I spent a lot of time sitting on the floor with him, calming his insecurity, encouraging him to check out anything he considered scary, rewarding him with treats for approaching and checking out the scary object. I also taught him "Quiet" . It took many months but now he only barks occasionally and stops as soon as I ask him to. My Corgi was around a year old. If yours was not a barker before, you have a chance. If his barking is ingrained, by age 7 it would be hard to turn around. How well do you know the previous owner? Often people giving up a dog downplay the negatives.... I would not normally recommend it, but if you risk the landlord's ultimatum, which would cause you to give up the dog (assuming you could find him a good home under the circumstances) you may consider discussing de-barking with your Vet.
It may buy you time to work out whatever other issues he may have. Best wishes.
Be careful with the Prozac. I have seen dogs get aggressive on this medication. Something else you may try is a Citronella bark collar. These work well with some dogs and are quite humane, but they do not work with all dogs. I would buy it someplace where it can easily be returned if you do not see improvement in a week. You need to scold him and say "quiet" at the same time the collar activates. Treats should never be given when a dog STOPS barking, although he should be verbally praised. Treats should be given when you tell the dog "quiet" as you see a situation developing which may trigger barking, or if you can stop it in the first low grumble stage. Otherwise you unwittingly reward the barking, which is probably what the previous owner did. As for not wanting to give too many treats, I recommend using plain Cheerios. One Cheerio is next to nothing (just try sqishing it) but it has volume and crunchyness and will satisfy him. You can reward as often as needed with no worry of affecting his weight. A house sounds good, but a nusance barker is a pain to all no matter where you live because the bark carries a long way. It sounds like you know what you're doing and are committed to the dog. Good for you, he is a lucky one!
Is this your first Corgi? I ask because Corgis are barkers, only the rare one is not. Shedding, herding and barking are part of the package. For the most part, you hope to train the pooch early in life to respond to the quiet command, and they learn to comply- but its generally a problem with Corgis - controlled barking is a success- meaning they bark and then quiet on command. Herding and guarding your home is hard wired into them. Your trying to teach the little guy not to do his job.
My guess is the previous owners are not being candid - they wanted a new home for the dog and would probably say anything they thought would solve their problem. What was their excuse for abandoning a 7 year old dog raised from a pup? If the dog was a loved, well-behaved family member - how did they give him away? Have to wonder.
The other issue is what kind of life did this dog have before? Did it live outside? Sleep in a dog house in a back yard? Is apartment - house living a new thing for him? It possible the dog was a barker - but not as noticeable or troublesome because he wasn't an inside dog. Get a better idea of his previous life style.
I agree with the others recommending a vet visit. Thats a good starting place. 2 of my guys who were manageable barkers when young started going deaf in there old age, and with each passing year the barking got louder and more frequent because they could not hear themselves as they were going deaf. Other medical issues could be in play, perhaps being treatable.
Here are some other recommendations - a lot of work but dogs are a lot of work :)
Exercise - exercise - exercise. A good dog is a tired dog. Try long walks - dog parks - doggie play dates - doggie day care that has play care. Find games your dog likes to do - fetch - tug - anything to wear him out.
Next step is training. Bring in a good trainer to do a home visit and work with you on how to deal with this.
Landlord advice - I think the best way to head off landlord issues is getting people to like your dog- neighbors, folks in the same complex- the landlord. Assuming the dog is people, kid, dog friendly, introduce him to everyone. Spend time with the other dogs in the complex. The more people like you and the dog, the less likely they are to complain.
If all of the above fails - either try to return him or work with a good rescue agency to find a more suitable home. All states have good Corgi rescue programs - with people sitting on waiting lists for years to find a dog. What state are you in? Also RescueMe.org is a good national rescue agency
This is my first corgi but I've owned hearding dogs in the past, I'm aware that corgis bark, but everyone, including the vet agrees that his barking is not normal. As stated in an earlier reply we have already tried training and exercise to no avail.
Re: the old owners: they made the decision to rehome him because their circumstances had changed drastically from when they first adopted him 6 years before, and I think it's p not cool to accuse them of being bad owners because they wanted to find him a better home once they realized they were unable to provide the level of care he needed. I can't imagine how difficult it must have been to make that call, and they are still involved in his life. I talk to them weekly with updates and pictures, they love that dog very very much and to accuse them of abandoning him is not okay.
Cassie the Corgi barks... a lot That was the reason her prior humans gave for abandoning her at the dog pound.
Rescued her. Brought her home. Found she hardly barks at all, unless for a reason. Decided the previous humans must have been making up an excuse.
A few years later, acquired another corgi: a pup. Over time, Cassie started barking more and more and more and...M!O!R!E!!! Life became a nonstop barkfest. A fair amount of vigorous doggy play/competition (hard to tell which sometimes) went on all the time. Of late, the two dogs became more crabby with each other.
About a month ago, a bleeding wound appeared on Cassie's face. Assumed the pup had bitten her and decided pup would have to go back to the breeder. When I told my son this, he asked me not to return her and said he would take her. He wanted a second dog as a companion to his pal, a golden retriever. Wanted a large dog, but to keep Ruby from being rejected, agreed to board her for a week or so to see what would happen.
Made an appointment with the vet. Took the puppy (Ruby) to the kid's house.
In the absence of Ruby, the barking STOPPED. Like, completely stopped. Cassie ceased to yap altogether and peace reigned.
The vet took one look at Cassie and diagnosed an abscessed tooth. I said the last time I had her at the vet (closer to my house; the good vet is a 40-minute drive through homicidal traffic) they told me her teeth didn't need to be cleaned. He said cleaning a dog's teeth did not necessarily prevent dental abscesses. But he kindly cleaned her teeth while he had her knocked out to remove the decayed carnassial fang.
Son agreed to keep Ruby until Cassie recovered from the surgery. Feeling much better, Cassie remained quiet: no barkfests.
Cassie is cured. My son is sick and tired of Ruby underfoot (true: she is somewhat eccentric, especially when compared to a Golden). He now returns the pup.
A-n--n-d...the barkfests return!
I'm fairly sure the conversational yapping is a device to get the human's attention. Cassie's previous humans had a yellow lab and a cat and a kid. Dog + human: no barking. Dog + dog + human: barking.
Given that possibility, you might want to take your pooch to a behavioral trainer -- one who specializes in canine behavioral therapy (i know, i know...). See if that person can identify what's causing your dog to want to bark. If you know that, you may be able to alter the household circumstances in a way that will short-circuit the barking impulse.