I agree with Jane E that adding a meat based food with some grains would help add some weight. I would actually find a performance food. They tend to have a min of 30% protein, 20% fat, and some grain as a source of energy/carbs. I raise Aussies and these are very high energy working dogs that until about the age of three are really hard to keep weight on without a decent amount of fat in the diet.
The two that I have had the best luck with are Victors High Pro Plus and Annamaet Ultra. I know Nutrisource has a couple performance foods also.
Best of Luck!
