Dr. diagnosed and used Sargent's wormer. Trying to find out what Sergeants recommend, this is not on there package directions and cannot find from the company. After three times at the doctor for my dog I do not trust the doctor's confidence and it is getting expensive. The dog has been diagnosed with tape worms. How do we help our dog? When do you give a dog that is 70 to 80 lbs. a second dose of wormer if the first one did not work?