Advantages and Disadvantages of the Various Forms of Heartworm Preventatives

by Larry Letche, DVM


  1. Interceptor– This is a once a month chewable tablet that prevents Heartworms, Roundworms, Whipworms and Hookworms. This product is safe in all ages of dogs and can be started as early as 8 weeks of age. It has also been proven to be safe in pregnant and lactating bitches and it does not affect sperm counts in breeding males. The only problem with this product is that it is not currently on the market due to difficulties at the manufacturer. The FDA stopped production at Novartis due to a number of human drugs that it produced. All of the issues have been corrected and production has started again but with human drugs first. Last word is that Interceptor will be back on the market later this year.
  2. Sentinal– This is a combination of heartworm preventative and flea control known as Program. This is also a once a month chewable tablet. As with Interceptor it is currently unavailable at this time. With the addition of the flea preventative it can have some side affects if given at a larger dose in lactating and pregnant bitches.
  3. Heartgard– A once a month chewable tablet that prevents heartworms, roundworms and hookworms. It does not prevent or treat whipworms. It has been used the longest and is safe for puppies, pregnant and lactating bitches and stud dogs. This is the best alternative to interceptor.
  4. Iverhart Plus & Tri-Heart Plus– These two products are the same as Heartgard Plus but manufactured by different companies. The only difference is cost.
  5. Iverhart Max– This product includes drugs to kill tapeworms. It has not been tested on pregnant and lactating bitches. There is caution for the use of this product in stud dogs as it may cause testicular hyperplasia which can affect fertility.
  6. Revolution– This topical agent prevents heartworms and helps to control fleas and ticks. It is applied once a month. There is currently no information on the package insert concerning safety in pregnant and lactating bitches or stud dogs.
  7. Advantage Multi– Also a topical agent that is applied monthly for the prevention of heartworms and the control of fleas. It also eliminates roundworms and hookworms. There is currently no information on the label concerning pregnant and lactating bitches or stud dogs.
  8. Pro-hart– This is a six month injectable heartworm preventative that must be administered by a licensed and trained Veterinarian. It is also used to control hookworms. A dog must be over 6 months of age to get this product. It was taken off the market by the FDA a few years ago due to severe reactions. The labeling warns of anaphylactic reactions, possible digestive bleeding and neurological side effects. No information is provided concerning breeding dogs, pregnant and lactating bitches or stud dogs.