My 11 year old Brittany Spaniel disloacted his jaw about 7 weeks ago. The vet popped it back in place but informed us that he should no longer eat dry dog food because the crunching could cause it to pop out again. We began a slow shift between Purina Dog Chow to Purina soft Alpo Prime cuts. De seems to be doing alright as far as his digestive tract is doing. The problem is that my dog is losing weight. He was 39 lbs before and is now more likely around 30 lbs. Also, his skull is more pronounced and appears to be mis-shapened. We increased the amount to food and thus slowed down his weight loss quite a bit. We feed him about 14 oz of food, twice a day. Somehow, it doesn't appear that he is getting enough nutrition. Does any body know if that it enough food based on dog breed and weight? (He should be 35 lbs ideal)

Perhaps you could switch him to one of the top quality canned foods - Merricks, Nature's Variety, Innova Evo. Purina is pretty far down the ladder when it comes to quality and you're right, he's not getting the nutrition he needs. I bet you could get his weight back up with a change to a better food.

You should get bloodwork run on your dog to see if there is not another reason why he is losing weight.

The best thing you should do for your dog is to take him back to the vet. They know things that we don't. If it's serious, then your vet could tell you, not us.
hope I helped, go to the vet!

The first problem I see is what you are feeding him. Just look at this website:
http://www.dog-food-secrets.com/alpo-dog...
http://www.fda.gov/oc/po/firmrecalls/pur...
He needs to be on something that is raw, like Innova EVO. These will provide the appropriate nutrients that is needed, not just a bunch of grain nutrients. It is VERY IMPORTANT to feed him the right diet. Since he is an older dog, it will probably take a bit for him to adjust to his new diet. But don't keep changing the food. This will cause digestive problems as well. Another benefit of raw dog food is that there is less poo. And that's always a plus. Please get your dog off of that poison! He needs something healthier!

take him back to the vet, if his head is misshapen, he may have reinjured his jaw. 28 oz of food should be more than sufficent for him

First, you're feeding him crappy food. You need to switch to a decent brand, nothing from the grocery store or Petsmart. I suggest:
Artemis, Merrick, Evangers, Wysong, Wellness, California Natural, Health Extension, Chicken Soup, Solid Gold, etc.
I would feed 2-3 large cans per day to help him gain weight, then 2 cans or so a day to maintain weight. Also, make sure he's getting enough fluids, sunken features are a sign of dehydration.

It's the food.. lack of nutritional value.. Check out the Canidae canned food if you are looking for soft food.. Dogs love it and it has actual nutrition in the food...

Feeding proportions are usually according to the food manufacture.
If it doesn't say on the label, go to the food maker's website to see if you are feeding him enough for his body weight.
If he is still having problems, call your vet, it may be something other than what you are feeding him.

Purina canned food is not a very nutritional food, most canned soft dog foods in fact are composed mostly of water. Therefore your dog might not be getting enough nutrition. If you are going to have to feed a soft food, I would actually suggest softening the hard food that you were feeding or feeding a science diet brand of soft dog food. Probably one of the prescription diets. i/d is a good one. Also alpo was included in the dog food recall so if you have been feeding this for a while I would take your dog to the vet immediately to make sure your dog hasn't been poisoned, it might not be showing any signs right now, but it could be having kidney failure. (this too will cause weight loss). It needs to have a wellness blood screen to check it's chemical balances in it's blood.

Some animals dont adjust to food changes very well. I'm guessing that he will get back the weight slowly, but surely. Did the vet mention anything about him being overweight, or that he will have side affects to the food? I think that you should call your vet with this question. He can probably answer over the phone, or at least one of the assistants can. Has your dog been acting like hes hungry like looking in his food bowl multiple times a day when there is no food in it, begging for food, etc.? Ask yourself this. He might just be getting the affects of old age.