Have you had him checked for worms or other health conditions? It seems odd that it started after adulthood and that you’re having to feed SO much, I’d do a fecal to be on the safe side.
That said, we have two Cattledog mixes around your dogs age. It is hard to keep weight on them, our vet admitted that he NEVER tells clients their dogs are too skinny, but that both of ours could gain a little. We feed LoJack (a German shorthair cattle dog mix) Merrick chicken and rice dry food, two heaping cups a day. We add a little more if we notice him thinning out too much. Quincy, who we think is a purebred Cattledog, gets 2-3 cans of chicken soup adult (for about 1000 calories). He has some stomach issues and can’t have dry food. They are both around 40lbs and both are around 21 months old. Both are neutered males. We don’t have a large yard, so their exercise is mainly walks and wrestling with each other. They’re both kenneled while we are at work – I imagine they’d need more food if they weren’t. And we haven’t been exercising them as rigorously these past few months, so it’ll have to increase if that changes as well.
I never use the bags recommendations, but instead figured out how many calories I need to get them each day and then figure out the food from there. Some brands is more, some less. Most have the calories per cup or can printed on the label, or on their website.
We’ve used Nurrisource grain free in the past as well with success, and are starting Quincy on Honest Kitchen soon. My moms dog does beautifully on Wellness (he’s not a Cattledog, but its a good food to my knowledge).
Good luck! These crazy herding dogs sure keep us on our toes!
