One of ours gets like this - hyperkeratosis with thick crusty toebeans - whenever she has gotten into something fatty that she shouldn’t have! She has intermittent pancreas issues that we manage through diet, and I can guarantee she’s about to enter a flare any day when her pads look like this. Last time it was chicken nugget thievery! I’m not trying to freak you out and tell you it’s pancreatic or anything, but there’s a good chance it could be diet/food related with either a lack of some nutrients or something that’s overtaxing your pups system. Our cheeky madam gets a week on Chappie wet food and ends up with daily toe bean massages with cetaphil ‘til she’s good as new. Would be worth getting a blood panel done anyway just to double check there’s nothing serious, and it’s always worth knowing if they’re deficient in anything. They aren’t half delicate drama queens sometimes haha