Due to MVD, being overweight is nearly a death sentence for a Cavalier. I guarantee you the best way to prolong your Cavalier's life is to keep it's weight to a MINIMUM! Not overweight even a little bit. THIN! If your Cavalier is even a little bit overweight, it will hasten the onset of MVD and death. Do not allow this to happen.
HOW MUCH DO I FEED AND IS MY DOG OVERWEIGHT?
There is no way to tell you just how much your dog will need so far as quantity of kibble. Cavaliers vary GREATLY in their activity level. I know some 20 lbs. dogs that only need 1/2 cup of food a day and others that need a full cup or even more. I know some 10 lbs. dogs that only need 1/3 cup of food a day and others that need a full cup or even more. It is too dependent on the metabolism and activity level of each individual dog. You will have to use a hit and miss approach to figure out which amount is right for your dog. Try 2/3 of a cup to 1 full cup per day for an adult Cavalier over 1 year of age and watch to see if the dog is gaining weight or losing weight. Adjust accordingly. If they seem to be getting heavier, cut back. If they seem to be getting lighter, feed more. Also most dogs will need more food when the temperature outside is colder. Now how do you tell if your dog is getting heavy or not? Hopefully the following will help you figure that out.
Your vet is not the person to ask! Over the years I have been amazed to find out that vets are very reluctant to tell an owner their dog is overweight until the dog is quite overweight--till the dog is so overweight it is very hard to get it off. Here are two ways to judge if your dog is overweight.
First is the rib test. Look for a hand towel or dish towel in your house. Fold it in half. Find a wire crate, wire fencing or expen, something with wire not spaced too far apart. Rub the towel over the wire several times and get used to how it feels. How does the wire feel, how easily does the towel move under your fingers? Now rub your fingers over the ribs on your dog. It should feel quite similar. A VERY thin amount of skin that moves easily over the ribs--ribs which can easily be felt and counted. If you feel some padding under the skin, the dog is mildly overweight. If you feel a lot of padding, you have to press a bit to feel individual ribs, and the skin doesn't move around easily--the dog is definitely overweight.
The second test is the waist test. Stand over your dog and look down at it while it is standing with the dog facing the same direction as you are. You can also use your hands with this test. As you are looking down at the dog you can see where the ribs are. If you are not sure run your hands from the shoulders over the ribs down to where the ribs end so you will know just where the ribs are. After the last rib, and before the hips, you should see a distinct indentation--a waist. If you can barely see an indentation, the dog is mildly overweight. If there is no indentation at all, the dog is definitely overweight. The following are three pictures of dogs. None are really overweight, but they will help somewhat in teaching you what to look for as some are have a tinch more weight than they should. I hope to get a picture of a very thin Cavalier and a very heavy Cavalier at some point in the future.