Write to your airline to get their policy in writing if they cover dog food for service dogs. The airline I usually fly accepts food for service dogs as medical equipment (I have it in writing in case I ever have issues with my service dog's bags) on both domestic and international flights. I have never had an issue with the couple other airlines I have flown accepting the dog bags as medical equipment, either. The DOT should never have stated that food for a service dog isn't medical equipment, as it is the most necessary thing and can't just be bought anywhere unless you feed terrible food, which I wouldn't do. I can't even buy the food near where I live (have to order it from Chewy, a site I highly recommend), much less on a trip in the States and definitely not in another country where only terrible food can be found (and feeding raw would be ridiculously expensive, especially on long trips, at three times the price of meat in the States).
If they don't cover food, I would have it shipped there. If Chewy carries it and your total is $49+, two-day shipping is free. You can buy doggy energy treats from them, too; I like the WetNos bars and the Barkworthies bars, though they're both definitely ones you'll need to feed in an out-of-the-way spot while your dog is off-duty because they are hard chews and a bit messy.
I don't increase my dog's food at Disney or any other activity, but I do give energy treats (I used to give the little ones from Zuke's until I stopped buying from them when they got bought by Purina).
If you used a conversion tool/Google to calculate the amount of dog food in each bag, do not rely on that! A pound of lightweight popcorn and a pound of rocks are far from the same volume (amount of cups). Either ask the dog food company approximately how many cups are in each bag or measure it out yourself when you get your next new bag.
NEVER put medication in a checked bag!!! Meds can be stolen or your bag could be lost for a day or more (or never found).
