I'm wondering if the dental problems could be making him cranky? There is credit care for that sort of thing. You don't have any interest for longer than a year, and monthly payments are very reasonable.
CareCredit Healthcare Finance - Payment Plans and Financing for Cosmetic Surgery, Dental, Vision, Hearing, Veterinary & Other Medical Procedures I agree with the others, keep him away from the puppies, they can be very aggravating to an older dog. Best of luck!