Last night we were blessed to have Dr. James Crisman, of Pfizer Animal Health, come to our South Mississippi Veterinary Medical Association (SMVMA) to speak on the topic of heartworms.
Now, you might well think that there is nothing
new to know about a parasite that has been recognized for well over one hundred years. Not so, like most living things, Dirofilaria immitis undergoes constant change.
For example, we have known for about five years that dogs on heartworm preventive have been getting heartworms at an increasing rate. Study after study shows that the leading cause is failure to administer heartworm preventive on schedule. Here is a list of common mistakes:
- failing to give the medicine on the same day every month.
- thinking that being a few days late is not a problem.
- missing entire month(s).
- forgetting to refill the medicine when refills fall between doctor visits.
Apparently, much of heartworm preventive failure is actually failure to prevent!
These same studies show that pet owners (dogs and cats) who purchase their heartworm preventive 12 doses at a time are less likely to miss doses.
I must emphasize again: Heartworm preventive is a monthly medication. It is not an every 33 days medicine. It is not an every-other-month medicine. It is not a whenever-you-think-of-it medicine.
Having said that, we also know that while owner compliance is a major factor in this trend, it is not the only factor. Researchers are looking at a number of parameters about the heartworms themselves that are contributing to this trend.
Some of the things they are examining have to do with the adult worms. Some pertain to the microfilaria, the offspring of the adult worms. Some even have to do with changes in the intermediate host, the mosquito. Case in point: The introduction of the Asian Tiger mosquito, Aedes albopictus, changed the picture of heartworm transmission significantly. An Oriental invader, she is a much more aggressive feeder than the native mosquito. Natives may feed primarily at dawn and dusk. This striped menace feeds all day long. Every bite has the potential to transmit heartworms to your pet.
That’s right. It takes only one bite from one mosquito to transmit heartworms.
Researchers have no firm conclusions on the biological factors involved in heartworm preventive failure. MyPetsDoctor.com will keep you informed as more information comes to light.
Check back tomorrow for more on heartworm disease, Dr. Randolph.