You need to be careful when choosing which heartworm prevention medication that you give your dog, given the seriousness of a heartworm infestation.

For example, Proheart Six, a heartworm prevention medicine released in 2001 with one injection administered every six months. Seemingly providing a worry free way of taking care of heartworm prevention twice yearly, it came under close scrutiny from the FDA in the USA after more than 5,000 reports of adverse reactions were received, including 415 deaths.

The results from the investigations conducted by the FDA proved that ProHeart 6 caused a much higher amount of deaths than regular, monthly heartworm medications. The comparison of ProHeart 6 with 138 deaths in one year, was overwhelmingly higher than the six deaths reported yearly from Heartgard heartworm protection and Sentinel. (FDA May 3, 2004)

Without wanting to scare any pet owners out there, it's wise to remind people that giving any kind of dogs heartworm control can cause allergic reactions. In the worst case scenario, they might result in the death of your pet.

The FDA 2004 study showed that Revolution had a total of over 8500 adverse reactions and 36 deaths each year; the average number of reactions was about the same as for ProHeart 6, but since the latter is newer to the market, ProHeart 6 has a death rate thrice as high.

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.

Indeed between 1995 and 2004 only 84 deaths were recorded for Interceptor heart worm protection. Heartgard, which uses ivermectin for heartworm protection in its Heartgard chewables, had an average of 355 reactions and 6 deaths.

Sentinel, another flea, parasite & heartworm protection medication, scores lowest with adverse reactions and deaths. Between 1999 and 2004, this heartworm prevention for dogs caused less than 900 adverse reactions, making an average of 233 compared to Revolution heartworm treatment for dogs at 1737, and the total number of deaths was 25, making the average 6.

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.

Keep in mind that these statistics are resulted from millions of dogs that have received medications from all over the world. Since your pet is a member of the family and not a statistic on paper, you should speak with the family vet so that he can aid you in choosing the right form of preventative.

Please do not underestimate the devastating effect of heartworms in dogs. By choosing an easy to administer monthly dose of heartworm preventive medicine, you can spare your pet a lot of hardship.