I just got into these too! I'm using them for desensitizing my dogs to grooming procedures/handling. Basically as long they don't pull away while I'm rubbing their feet/ears/etc they get to eat out of the tube. When they pull away or I stop the tube gets capped. It's been a training game changer!

I'm lazy so I've just been filling them with canned dog food, but I might try canned pumpkin next.

Edit: I'm using these ones, they're easier for me to fill and squeeze. ChooMee Reusable Food Pouches,... https://www.amazon.com/dp/B01GH7ZOSM?ref=ppx_pop_mob_ap_share

I haven't decided if I'll put much effort into washing them yet, they say they can go in the dish washer so I'll try that. I'll refill them with the same stuff once or twice as long as the contents didn't get hot or they weren't out of the fridge for more than an hour or two.