Older Boxer and the use of fish oil capsules

Question
I have a female Boxer (approx. 11 yrs) she is having trouble getting to her feet quickly or walking with her usual gait when she first stands. She is a little too heavy but won't tolerate less food without getting into anything she can search out or aggressivly grab. I"m sure she has arthritis.  I was advised at the Health Food store to begin giving her fish oil capsules for her joint problems, and age related issues.  Is this a good idea and
has anyone else done this with success in Boxers?  Also
she has developed a habit of snatching an empty box, bag,or
toy - and guarding it very aggressivly even tho it's nothing she really wants.  I can usually distract her with a treat while someone gets the "treasure"  So far she has never bitten anyone, but I'm getting concerned about the grandchildren.

Answer
As far as the fish oil-- that is fine, but it is more for a healthy heart and blood pressure than joints.

You can research online, canine joint supplements, and find some recommended supplements. (Pet stores carry it too)

I do suggest feeding her a special senior dog food that is formulated for joint health. Ask your vet, or research it online.

These two things will help her.

She should be on some type of arthritis meds and pain meds. If her stomach can tolerate them.

Get her the most comfortable bed as possible. They do make special beds for arthritic dogs. Sometimes it helps to have a low-raise bed for her to get out of, and low enough for her to get into.

A heating pad on her leg and hip joints help also. I would use that if she is particularly showing pain and stiffness.

Do check with your vet about meds for her. They do help, and treat her special and love her as much as possible, keeping her as comfortable as possible. She hasn't much time left.