Proheart Six, first available in 2001, is a medication administered as one injection once every six months. This was originally seen as a safe & simple way to provide heartworm prevention every six months. However it peaked the FDA's attention after more than 5,000 reports were filed detailing poor reactions, which included 415 deaths.



ProHeart 6 caused many more deaths and adverse reactions than monthly heartworm treatments, according to the FDA. Reactions to ProHeart 6 led to 138 deaths each year, while reactions to Sentinel and Heartgard heartworm protection were as few as six per year.

While our intentions are not to scare pet owners away from necessary treatment, we feel that they should know that allergic reactions can result from heartworm control. It is possible that death could be the result of the medication. Obviously this is the worst-case scenario.

Here are the facts from the 2004 FDA source: Revolution heartworm protection averaged 36 deaths a year and more than eight and a half thousand reactions, so although the number of reactions was almost twice that of Proheart 6, the drug has been on the market longer so the average number of reactions was similar to Proheart 6, but the death rate of Proheart 6 was over three times as many.

Revolution is not necessarily unsafe. The high numbers of deaths are partially due to its very widespread use, however you should still educate yourself on the facts. Only 214 negative reactions were caused by Interceptor for canines, which is eight times less than Revolution. Interceptor averages a mere nine deaths per year, compared to ProHeart Six's average of 138.

Interceptor heartworm protection had only 84 deaths recorded between 1995 and 2004. Ivermectin is the active ingredient in Heartgard heartworm protection, which led to an average of six deaths and 355 adverse reactions each year.

Causing the very least amount of allergic reactions or deaths was Sentinel, a flea, parasite and heartworm protection medication. Statistics show that information gathered in the years of 1999 through 2004 that Sentinel heartworm prevention for dogs resulted in 900 reactions which is an average of 233 as opposed to Revolution heartworm treatment for dogs which had 1,737 reactions with a total of 25 deaths averaging to be 6 annually.

ProHeart 6 should only be used for preventative heartworm control, and should not be used if heartworms have already become established. Monthly heartworm prevention and treatment is a popular choice, but numerous vets maintain that Proheart is safe. In 2007 Proheart 6 was still on the market as a heartworm prevention medicine despite the fact that it was recalled in September 2004.

We realize your pet is a member of the family and not a statistic in a dogs heartworm protection table, but be reassured that these are the results of millions of dogs being given the drugs worldwide. Speak to your vet if you are at all concerned, but do choose a prevention.

Heartworms are devastating to any dog and should not be taken the least bit lightly. Choose a monthly dosage of heartworm preventive medicine for your beloved pet so as to provide the best care possible and protect him from any unnecessary pain and suffering.