my beagle biting

Question
Hi, I have an 11 year old beagle whom we have had since he was 10 weeks old.  My husband and I adopted him when we were newly married and now have a 7 year old and a 4 year old.  He has always been a very dominant dog and we had a tough time establishing alpha since he was young as we had similar issues as one of your readers with a 3 month old puppy biting and growling. We did take him to dog training for the first couple of years of his life and socialized him and thought that he had been trained out of his bad behaviors.  He has been a great family dog but every so often still gets very aggressive and bites us if we try to take away a piece of food that he has accidentally taken from the garbage or been dropped on the floor.  He has bitten me and my husband in these instances in the past, but it had been isolated by a chicken carcass or steak bone.  
Recently, though, he has bitten us while we have tried to stop him from running out of the house.  The kids may leave the front door or garage open and he will run out.  As we try to stop him by the collar, he has tried to bite us and has drawn blood from it. He will come back if offered a treat but usually I still have to chase him down the street.  Recently, he bit my son's play mate as he tried to stop him from running out of the house and it has worried us alot.  We love our dog and he is otherwise a very typical sweet beagle but now we are concerned that he may be getting old and may be changing for the worse in old age.  Fear biting is definitely something I have thought of because he does have bad knees that have been giving him pain.  We were told that he would require very expensive knee surgery to fix it and because of his age, recouperation time  and the chance of re-injury we have opted not to do it.  He still runs and jumps off of furniture even with hurt knees all the time.  
I am very concerned and am not sure what we can do if anything to stop this very scary behavior.  Can you please help us? Thanks so much!

Answer
Thanks for writing to me about this. I think there is a combination of things going on. There is fear biting or food dominance going on and also it does sound like he may be in pain. As they age dogs do get grumpy and previous behaviors tend to resurface.  First off just to address the pain issues, if he doesnt have the surgery then there is no reason why the vet cannot give you pain medications for him, specifically anti-inflammatories such as Deramaxx. It may make a big difference for him and he is old enough that you dont need to worry about long term use being an issue.

As far as the biting it doesnt sound as if he ever really did get the picture of who is Alpha. This kind of biting where he draws blood is serious, Lupe, it might be one of the kids sometime. I believe in keeping a dog for his lifetime and just like with our kids we work through whatever issues come up. It is my recommendation that you seek out a hands on trainer who can come to the house and do some one on one work with you and him before this excalates any more. There is little I can tell you via email that will help. Any time there is aggression it needs someone to come and observe and be part of the process. I cannot strongly urge you enough to take care of this ASAP. He also needs some work on running out of house as this appears to be a lifelong habit of his. All of these issues are fixable but you need help as I said by someone in person. Please follow up with your vet on the meds and they may be able to give you recommendations of trainers in your area.