Toy Dogs ...
Toy breeds, which often have tiny appetites and small stomach capacity, may also benefit from being fed a calorie-dense food but a careful watch should be kept on their weight and body condition score (see Managing your fur kids weight).
The following information is meant as a general guideline, and has been researched from other sources.
The extra energy for both working and toy dogs is best supplied in the form of fat, first because fat contains more calories per unit weight than protein or carbohydrate, and secondly because dogs appear to utilize the energy stores in fat more efficiently. The use of fat for energy also avoids the necessity to remove from the body the waste products that occur when protein is used.
Toy Dog Feeding Index