#1 - Check for Xylitol. Anything with Xylitol in it is not good for dogs.
#2 - If you find one without sugar or sugar substitutes, that would be best of all.
#3 - Oils...if you can find one without hydrogenated oils/palm oil, that's best.
#4 - And, maybe it's nitpicking, but low sodium is nice.
I would say, though, that no xylitol, and being picky about oils would be the most important, in that order. Sugar 3rd, salt last.
If you could get cheap raw peanuts, or roasted, and could find a 2nd hand blender, you can blend your own with a little of whatever oil you prefer. If raw, peanuts can be toasted lightly, then processed.
I've found it easier to get peanut butter here, than reasonably priced peanuts. But, maybe you can find a line of them.
I hope that this helps.
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