My dog has brittle claws - are their any supplements which would help improve his claw condtition?

I feed my dogs Taste of the Wild, it has no grain or by-products. I started them on it 3 weeks ago, and it has done wonders with their coat. One of my Doxies is a chocolate, his coat was always dry, and didnt even look chocolate, until now. I also give my dogs NuVets vitamins, which was required when I bought my Isabella Dachshund, as issys tend to loose their coat.