no sleep

For the last month my dog has been waking alt all hours of the night wanting to eat.  It started out he would get up about 4am, not he is up at 11, 1am and 4 am.  I try to let him out thinking he needs to use the bathroom but all he does is run to his bowl.  I usually give in and feed him or he will continue to run up and down the hall until he is fed.  He is not gaining weight and is still active as ever for 13 years.  I switched his food from weight healthy to adult dog and his feeding time from morning to evening, but none of this has helped.

[ginger899]

Try him on 2 or 3 small meals a day rather than one. (I guess you mean he does have one meal a day?) If he's an active dog, and gets plenty of exercise, he probably does need to be fed at least twice.
I have an active, older dog too, and give her breakfast and dinner, and a healthy small snack late evening. She doesn't gain weight.
I feel maybe 24 hours is a long time to go without a meal.

That might fix the problem....
If not, then I would advise speaking to your vet. There are a few reasons why his appetite may have changed. Occasionally pituitary tumors can cause this (many of them are very very tiny, and often benign, but can cause changes like this) Has he been taking on a lot more water lately than he usually does? An over-active Thyroid can also cause similar symptoms.

There is another possibility, and that is he could have a form of mild dementia. This does occasionally happen with dogs. I have no hands-on experience of treating this, but as far as I have heard, there are medications which relieve the symptoms.

I don't particularly sense that it could be this...but it IS possible this is behavioural. That he maybe woke up snack-ish one night, asked for food, found that it worked, and is milking it for all he can get? Dogs are quite capable of that kind of thing!
But like I said, my instinct is mainly he might not be getting quite enough to eat during the day....and my second thought is he may need checking over at the vet's.

[Ghilly]

Some dogs develop huge appetites when they reach old age.  A noticeable increase in appetite is called polyphagia.  Sometimes it is accompanied by polydipsia, or a noticeable increase in thirst.  This can simply be a sign of old age or it could be a signal that something is wrong.  The only way to figure out the cause is to visit the vet and let them do tests.  Diabetes can cause both an increase in thirst and an increase in appetite.  Some dogs act like they never get enough food and will actually even do things they never did before to get that food.  Well-trained dogs will break training and raid trash cans and eat whatever they can find.  

It's possible for dogs, as they age, to develop poor nutrient absorption leading to an increased appetite in a search to satisfy the hunger.  As much as they may eat, their bodies are not absorbing the food adequately so the dog still feels hungry.

You need to schedule an appointment with your vet.  Some simple tests should be able to figure out what the cause is and you can either begin treatment if it is something that requires treatment or adjust his feeding schedule to give him more meals a day in an effort to satisfy his hunger.  Please let us know what you find out at the vet's.  

Ghilly