If the vet said he was healthy, he shouldn't be wormed again.
And do pay heed to what AngelzFyre said. I have a dog that cannot take anything with Ivermectin in it, but she can safely take Interceptor - another h/w preventative.
And do pay heed to what AngelzFyre said. I have a dog that cannot take anything with Ivermectin in it, but she can safely take Interceptor - another h/w preventative.