I have an 11 year old rotweiller who I recently had treated for tapeworms. Since this time I can not get him to regain his weight. I have been combining canned and dry food, but it is not helping.

It is very unusual for a healthy dog not to eat all it needs. I would first evaluate him as illustrated in this link, http://www.puppychow.com/products/popup_body_condition.aspx You may be comparing him to over weight dogs while he is eating what he needs. If you determine he is too thin, get back with the vet. It is possible the tape worm isn't gone, or there is another problem. If the vet can't find a problem, his ideas don't work, post back.

You are feeding a concentrated, meat based chow such as Pro Plan or Iams? If a dog won't eat enough of something like them to hide its ribs, you need to find and fix the problem, not tempt it with rich food. It the ribs aren't showing, there isn't a problem.

Did you or your vet decide the initial weight loss was caused by tapeworms? Did you actually see them? Did the vet give you the tape worm medicine? Or did you buy something over the counter?

There could be many reasons a dog of his age is losing weight and some could be serious. Because of his age I would definitely take your dog into the vet and have a geriatric blood screen done to rule out any problems.

Hope this helps,
Molly