My dog has been vaccinated every 3rd year with Canigen and every year with Canigen Lepto Ci. We have moved and new vet uses Vanguard vaccines. The dog is due Lepto vaccination as had Canigen dhppi 2018 is not due again until 2021. When I said I wanted Lepto only the vet refused to give and said I must restart as different brand. It is my understanding that the dog still has protection for dhppi for at least another year so only needs Lepto ci or 2. Is the vet correct or am I please.