My 11 years old Bishon Frise constantly barks when there's no one at home. Even if we stay away for 4, 5 hours. She got raucous once for barking too much.
What could be causing that and how can I train her not to do it anymore?
You can't expect your pet to keep mum if you are not with him.
Get the dog someone to give him company. When there is no one at home, you can consider leaving him at some neighbors home awhile.
You can request somebody to look after him while everybody has gone from your house.
You can provide him something to play with. This is not very effective in every cases. But in 50% cases, it would work. Give a bone toy or a ball to chew with. My own dog likes to play with them and we got rid of the barking problem.
Dogs do not like being locked. Just letting him be may work.
I think she misses you. Dogs are pack animals and you're part of her pack. When you leave, she has effectively been separated from her pack and that can be very distressing. One way to address that is to add to the pack, another dog, but if you can't do that, then another animal (surprisingly, even a cat) may give her that sense that she's not alone enough for her to stop. I don't think, without that pack substitute, you're going to have a huge amount of luck working her out of it.
I would like to propose another idea.
I've experienced the same problem and noticed that proper exercise, especially in the hours prior to them being left alone, can help calm their behavior.
In many occasions, anxiety causes them a high level of distress, to the point any noise or movement results in them barking for an extended period to an invisible threat. However, the most exercise they do, the more physically and mentally relaxed they are (socializing with other dogs also helps). The more relaxed they are, the less likely they will be bothered by your absence (especially when they spent four of those hours sleeping!).
Previously, I've got many complains from neighbors of incessant barking; and so I started to take her to park or for extended walks/runs very early in the morning before work. It has both improved her psychological state (she's less anxious, less insecure, more calm and happier) and reduced the complains from neighbors.
Also, remember that in your absence the dog will do its best to protect your/their home. It is part of their instinct. For them it is a purpose, a 'job' if you will; and barking is one the tools they use to get the job done. Be very careful when repressing this instinct (with collars, gizmos, etc) as it can cause further psychological issues and/or sense of uselessness in the dog.
She is probably lonely. Also, she wants to protect the territory - and since the rest of her pack is away, she must do so herself.
In addition to the great suggestions by @Mistu4u, you could make a recording of your own voice, and have that play while you're gone. 4 or 5 hours might be a bit long, but for shorter periods of time this could work. (I'd prefer to try @Mistu4u's suggestions first though).
If the dog can't be brought to the neighbours, they can still help - if the dog can hear them and they can hear the dog, they can talk to her to comfort her.
People here has answered very well but if nothing helps then barking control collars can help as a last resort. I know its little rude to your pet but giving pet a company doesn't always helps and sometimes building/neighbor restriction can force you to do so with your pet. My sister Labrador also constantly barks when he is alone, even in presence of her second dog French mastiff. We didn't used the collars but there are some collars in market which doesn't give electric shock but just vibrate on barking which are less effective then electric collars but it doesn't harm the pet.
I got a lot of complaints about my dog barking, and I've gotten that under control, so the advice I found might also work for you. If your dog is barking due to separation anxiety, you can try the following:
I also purchased a cheap Wyze camera and set a sound alarm - this helps me to know if my tactics are working. It took a week or so before my dog settled down, and now when I check in from my phone, she's mostly sleeping. I believe you can talk through the camera, but I wouldn't recommend that unless you've given the above a proper try, because it could cause more worry rather than helping.
I have seen Tv programs saying how to quiet a dog, and they have said that You get a ball, with a hole and you put in dry or moist pet food inside. The dog has fun trying to eat the food, and concentrates on eating rather then barking. * This can be done in a Cage.
She may be lonely, so you should maximize your time with her, so you may want to get toys.
It was shown as many pet owners were struggling in apartments as they kept barking.
Leave her toys with hidden snacks inside and put in many hidden snacks in her cage to give her something to do. It may take a while for her to start enjoying this but it will eventually make her pleased about it. Make sure its a challenge before she can get it so that she will be satisfied. Make sure the treats are dry cookie treats or else they will go bad very fast.