Amazon is expanding its online pharmacy to fill prescription pet medications, the company announced Thursday.The company said it has added "hundreds of commonly prescribed pet medications" to its U.S. site, ranging from flea and tick solutions to treatments for chronic conditions.Prescriptions are purchased via Amazon's storefront and must be approved by a veterinarian. Online pet pharmacy Vetsource will oversee the dispensing and delivery of medications, said Amazon, adding that items are typically deliver ...