I make my lab carry her food in a harness/pack, when I'm backpacking or scouting. I did have to start putting her food in a water proof dry sack. As soon as she'd see a creek or one of the lakes, she'd head straight for it.
I use a ruffwear pack for my Airedale. Put a couple water bottles and food in the panniers, used it yesterday and she was crawling over/through a pile of downed trees and held up very well
Ruffwear Palisades. Made really well. I tried a cheaper one off Amazon. She had it tore up pretty fast. No issues with the Ruffwear though. Only used it last summer though.
Going on our fourth season with the palisades, highly recommend it. Ruffwear makes other nice packs, but the features on the palisades are worth the extra bit of $$.