Thaks for the additional information. It is helpful.
One thing you desperately need to do is get him obedience trained. A dog should not be growling at his owners regardless of the reason. If a dog is in a lot of pain, they might growl if they think you are going to make that pain worse, but a well trained dog is still unlikely to growl even then. At his age, which is considered elderly even at 7 and thus may be experiencing some pain due to arthritis or joint issues. In addition, behavior problems can develop as the result of hypothyroidism which is a problem in the breed. Read about this here:
Hypothyroidism can cause behavioral changes as well as sudden aggression so you should rule that out. If a medical cause is ruled out, then it is behavioral in nature. In that case, start obedience training. Dogs that are acting aggressively toward their owner and others needs training by the owner so the owner can be seen as the boss. Dogs growl to reprimand others or warn them. If you ignore the growls the next step is to nip or bite. Dogs do not reprimand their boss. The fact that the dog is doing this shows he either has a medical issue or feels that he is the boss. Obedience training helps because each time a dog obeys a command (even if for a treat) they become a little more submissive to the person giving the command. So training leads to you being the boss. As the boss, you give the reprimands, not him. He also is required to do what you tell him to even if he doesn't want to.
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.
So I would start with a good physical and thyroid panel with bloodwork. In addition start the training. Use hot dog slivers as treats for training as they are high value treats and most dogs will gladly work for that treat. Liver is another good choice for treat but messier. All family members will need to work with him and who ever comes to take care of him when you are gone. You can also keep him socialized by having friends give him commands and then treats when he obeys. These things should help if it is behavioral in nature.
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Since there have been recalls on certain foods, please check the following site to be sure the food your animals eat is not affected. If it is affected, contact your vet as soon as possible. Have your dog seen if they have any symptoms.