OK . . .couple of things:
1) Are you sure they are getting fat? I know this sounds like a silly question, but I would not go by their scale weight alone. There is a visual test vets perform which is either done to a scale of 1 to 5 or 1 to 10. On a scale of 1 to 5 a “3” represents good healthy weight, 1 is emaciated and 10 is obese. What your vet will do is look at your dog from the spine downward. He should be able to see your dogs ribs (the outline) without being able to put his fingers in between them. Your dogs should also have a high “tuck up” meaning that where the abdomen is towards the hind legs, the dogs stomach should appear to go up ward and the dog should have a “waist” if your pup resembles a sausage on four legs, you’re in trouble.
2) You are feeding Eukanuba? Wet or dry? Wet generally has more fat but if memory serves, Eukanuba, overall, has a high fat/protein content. You might consider switching to a food with a lower fat content (I feed Solid Gold Kibble that I know get from Yorkshire Terrier Rescue). I also like the
http://www.waggintails.com website as they have many excellent quality dog foods and they allow you to compare product labels so you can pick out something that has less fat than what you are presently feeding.
3) While I think its great that you can feed your dogs three times a day, which with these little guys does ward off hypoglycemia, because you’ve broken their portions down into three meals, you may be feeding more than what is recommended (and even the recommended portion according to the manufacture’s label I find to be a bit on the high side). Calculate the total amount of food you give your dogs a day and then compare it to be sure you are not overfeeding
4) One of my dogs has Addison’s disease. As a result, he will be on steroids for the rest of his life. One of the unfortunate side effects is that he constantly hungry. However, because he does agility, he cannot get fat or else risk injury and joint damage. In order to keep his weight down but satiate his hunger, I add organic vegetable baby food into his dog food every night. Dog’s don’t digest raw vegetables very well but they can digest processed veggies which also serve as natural vitamins supplements and a good way to help those anal glands too (so cuts down on scooting as well). His portion size looks bigger this way, he fills up on roughage, but I am actually reducing his caloric intake.
If diet changes alone don’t help, remember that just like you, your dogs need exercise and may not be getting enough. I am neurotic enough to have a dog treadmill and to take my dogs to the beach for swims (or a dog pool in NYC in the winter) to keep them fit. Although you don’t have to sink to my level of neurosis, I strongly suggest looking into a) whether you dogs are getting enough exercise and b) and even if they are, can you increase their activity level? I know everyone schedule is tight and crazy these days but getting your dogs fit will also help you stay fit. People, particularly, WAY underestimate the fitness potential of small and tiny dogs. My four pound girl, last night, jogged for 20 minutes with a five minute warm and cool down. That’s probably two or three miles of jogging! She wasn’t even panting when I stopped the treadmill. If you take it slowly and remember to do a slow walk before and after each exercise period, remember to give your dog access to water, and make sure with your vet’s assistance that neither has any physiological problems, you can and SHOULD incorporate exercise into your dogs life (Frisbee, long walks, swimming, jogging, etc.).