Today marks the 8th birthday of my dog Cosmo. Every year on his birthday I post a little birthday tribute for said pooch in honor of him adding another dog year to his life, and giving me another year of happiness and companionship. So Cosmo, here’s to you. Happy Birthday. I raise a Jerky Treat in your honor. Using the Pedigree Dog Age Calculator, Cosmo is 48ish in human years for his breed and size.