In long term - I would make sure the dog is stilll getting the proper
vitamins which is different than for cats. Talk to your vet. Especially
if your cat is on special diet food. You want to make sure your dog
isn't missing something special in the diet that could keep him
healthier and live longer.
JQ

I had a cat (for 18 years) that would drop down out of a tree onto the back
of a German Shepard when he was in our yard.  He would sometimes ride the
dog across the street into his own yard and then jump off and come home.  
Now the yards were only fenced by a 36 inch chain-link fences, but that did
extablish territory for both pets.

Once the dog's owner showed up at our front door complaining about the fact
that our cat had been in their yard abusing their dog.  My wife informed
her that we had small children that played in our yard and if she didn't
keep her dog home we would let our mean cat out to play with their dog.  We
did have another cat at that time, but he was too cowardly to let himself
be seen by an intruder of any verity.

Eventually their dog quit showing up, or got hit by a car or something.

I do not think my cat actually took a bite of this dog, so maybe a response
in a thread about cats eating "dog" food is inappropriate, but it is a true
story!