I would definitely re-evaluate the Comfortis versus other options for your Barney.
Also, I wouldn't be too worried about the weight gain - they tend to gain in spurts. If you feel he is not eating enough, though, try NutriCal. You could use it as a treat a couple of times a day - gives a boost of calories. Until Mandie turned 6 months old, I gave her a little (I mean like a couple of squeezed licks) 2 times a day as treats. Don't over do it though because you could inadvertently cause blood sugar spikes and lows, leading to hypoglycemia. Just a tad and that way Barney will get some extra calories
