First Shield has permethrin which is usually not a good idea for sensitive pups. I'd try Advantage. If that doesn't work, I'd bile acids test to make sure the liver is okay. Should not see three reactions from three drugs... Advantage would be for fleas only. Advantix covers ticks, but also contains permethrin.
__________________ Crystal , Ellie May (RIP) , Rylee Finnegan , and Gracie Boo🐶 |