Zesty Paws, in conjunction with ChromaDex, is entering the longevity category for dogs. Healthy Aging NAD+ Precursor is formulated to promote metabolic health and cellular energy repair for furry friends. NAD+ is an essential coenzyme that features Niagen, which supports regeneration of NAD+ levels in dogs, the company says. One package includes 60 capsules of Niagen and a jar of the brand’s bacon-flavored Pill Wrap Probiotic Paste.