Currently all heartworm products for dogs are given on a monthly basis. These should only be given to dogs who have been tested for heartworms and found to be free of disease. The cost of testing is nominal and only requires taking a blood sample. Most veterinary clinics will conduct the test in a hospital laboratory and have the results 8 to 10 minutes later.

When your dog has been tested and is free of disease, they may immediately start heartworm preventative. However, if you wait more than 2 weeks before starting preventative, you must retest for heartworms. The medication should always be given consistently. If any monthly preventative is given more than 2 weeks late, the pet should be retested before giving that month’s heartworm preventative.

When given inconsistently, these medications may cause severe allergic reactions, causing anaphylaxis or possibly death. Due to the possible threat of allergic reactions, heartworm preventatives are a prescription only item.

Two types of heartworm preventatives are presently on the market, oral and topical. Merial and Novartis each produce oral heartworm preventatives. Merial has a product called Canine Heartguard (which is effective against heartworms only) and Canine Heartguard Plus (which also has activity against hookworms). Novartis also has two types of oral heartworm preventatives: Interceptor and Sentinel. Each of the preventatives available by Novartis comes as a flavored tablet. Interceptor can guardagainst hookworms, roundworms and whipworms in addition to heartworms. Sentinel is a combination product which, combines Interceptor with an additional flea-controlling drug. Sentinel must be given on a full stomach in order for the flea product to be absorbed.

The topical heartworm preventative is available from Pfizer and is called Revolution. Revolution comes as a 6-application set of single dose vials. To apply this product, the cap is pressed down until the tube is punctured and the cap is then removed. The dog’s hair is parted and the product is squeezed directly onto the skin in one or more spots along the back. Revolution is affective against heartworms, ear mites, sarcoptic mange, ticks and fleas. The cat version of this medication also works to prevent hookworms and roundworms.

All heartworm preventatives are given by prescription only. Many of these drugs will actually come with a manufacturer’s guarantee assuring that your pet will be free of these parasites or the manufacturer will reimburse for any treatment. These drugs must be obtained by a licensed veterinarian in order for the guarantee to be upheld. Often the manufacturer will have specials including manufactures’ rebates and additional free doses, which are available only from a licensed veterinary clinic.

Check with your local veterinarian for details!