My name is ***** ***** I’ve been involved professionally with dogs in the health and behavioral fields for over 18 years. It will be my pleasure to work with you today.
Actually the behavior you describe is one we often see with a dominant dog. However, there are some medical conditions that can cause sudden aggression and those may be a factor. Unfortunately, these would not be able to be ruled out without testing. Read more on these conditions on the following pages.
It sounds like your dog may be having issues with dominance aggression. Many dominant dogs are described as well behaved until you try to get them to do something they do not want to do, and then they reprimand you either with a growl or bite if you don't heed the growl. Things like taking away something they want, making them move when they don't want to, waking them up, etc can cause them to reprimand (bite) you. Often male dogs won't feel the same dominance toward a female but a male will cause them to try and dominate them.. A strong willed woman might also cause the same reaction as well.
Dogs that are allowed on furniture (even if put on the furniture) tend to feel that since they are elevated to your level or higher if on your lap, they mentally feel elevated as well in the pack order and thus are the boss. Keeping them on the floor can help lower them mentally back to a submissive position in the pack. So the first thing is to not allow him higher that the humans or even on the same level. In addition, humans shouldn't be on the floor with him either. A small short stool is enough to keep them higher than the dog when petting the dog. Attach a leash and use it to remove him from the furniture. Give a correction in the form of a short tug and firm "NO" when he attempts to get on and a treat when he starts not trying to get on the furniture. Thus you are providing negative reinforcement for the getting on the furniture and positive reinforcement for the desired behavior (not attempting to get on the furniture).
There are other ways to regain the dominant position in the house as well. The best way is to start obedience training. While a formal training class is great, you can start obedience training without a formal class. The following site is helpful in helping owners train their dog. Be sure and click on the link to the page on obedience at the bottom. and links on subsequent pages leading to detailed instructions.
Training works best if you train at least 30 minutes a day (two 15 minute sessions). I would start making your dog work via the Nothing in life is free program (NILF). It is outlined below.
I do recommend paper thin hot dog slivers as treats when training. Dogs are quick to obey for these types of treats and often ignore store bought treats. You will also want to keep a leash on him at all times initially to grab if he should disobey. I think you will be pleasantly surprised at how well your dog does with training. Dogs like knowing what is expected of them and they love the little paper thin slices of hotdogs that I use for treats while training. Give this a try and see how it works for you.
Be sure to use the leash to make him obey you. If he growls give a short tug to get his attention and a firm "NO" to let him know, you are not going to allow his aggression. If he is sleeping, give a little tug to let him know that someone is there so he isn't startled when being woken up. .
In addition, if the situation is not improving using the techniques on the previous website, you may have to consult a professional behaviorist. You can usually find a behaviorist by asking your Vet for a recommendation or you may be able to find one using the following site.
So definitely start training and making him work for his food and affection, etc.
I hope this information is helpful to you. If you would like any additional information or have more questions please don’t hesitate to press the reply to expert or continue conversation button so I can address any issues you still have . If you do find this helpful, please take this opportunity to rate my answer positively so I am compensated for my time.