Most people do not realise the importance of food to a dog.
If you have a dog that is fed, eats it and goes away happy you don't know how lucky you are.
The bad bit of feeding problems is that they are usually pretty extreme before the owner notices there is a problem - this is not a reflection on the owner, by the way.

For this problem... taking the food away from the dog and letting it watch the cats eat it will only prove to the dog that gaurding the food was the right thing to do. I can see why you thought of it... "if you don't eat it someone else will".
What the dog is seeing is, "I was sooo right to tell those kitties where to go 'cause they doooooo want to steal this stuff!"

Your dog is seeing feeding time as a daily dose of Look Who Is Boss Here.
You are getting worried about it, result for the dog.
The cats have decided doogie food is tasty and WANT it so dog asserts his authority - result for the dog.
You take food from dog and give it to cats - reinforces dogs belief that the most important TOOL in the house is it's food. - If you have control of the food you have total control.

Take control yourself.

Give the dog very small rations, I would suggest that you cut what your dog usually has in one day by half. (The reason for this is that your dog has forgotten what it is like to have an empty stomach. Empty stomach is a natural state for all carnivores - they have to have an empty stomach to trigger the hunt (not to be confused with the prey drive). It is not healthy for a dog to go through a twenty four hour period without feeling it is hungry.)

For very small rations give half in the moring and half in the afternoon/evening for three days.
Give the dog a break and do not allow the cats into the room where the dog is eating.
Put the food down, making the dog sit, and then , at first give the dog ten minutes to eat. You have to leave the room too.

As soon as ten minutes are up - go in and take the food away.
Do not give the same food to the dog at the next feeding time - give him fresh (it can be the from the same can or bag - just not the bowlful of food he didn't eat earlier.) (Also, don't change brand!)

What you need your dog to understand is that he doesn't have a dominance issue with the cats - it is with you!!!!

You are the giver of food - you decide on a fair time to eat it - you decide that it is taken away .....you are the boss, not the cats.

As the dog is never really hungry he can afford to use food as a trophy.

Please understand - I am not saying starve your dog- that would make things a lot worse!! Over a few weeks you need to find the balance of what your dog needs to stay healthy and what it can eat in ten minutes. An overload of food ar an overload of time to eat it is giving the dog the wrong messages.

Your dog is having a problem deciding who is boss in the house and is trying to use the food you give him as a lever. You need to make it clear to the dog that you are in control.