Is Heartworm Prevention a Scam?

April 24, 2013

Some interesting articles worth sharing.  Most of it does make sense!

The scam: multimillion dollar medical companies pushing heartworm/flea/tick prevention products year round
The heartworm has 5 separate larval stages referred to simply as L1, L2, L3, and so on. It also has two separate cycles which have to be combined to makeup the lifecycle of the heartworm. Only one cycle takes place in a mosquito and the other inside a dog.

The mosquito becomes infested when it bites a dog which is already harboring L1 (MICROFILARIAE). *This can only happen if the dog is also harboring the L5, which is the adult, male and female heartworm as the Microfilariae are their offspring. These Microfilariae can live for up two years in the dogs blood but must be taken up by a mosquito in order to develop any further. If they are not taken up by a mosquito to further develop, they will simply die of old age.

Once the mosquito is infested, the larva must then go through two stages of development or molts L2, and L3, before they can infect another dog. This, mosquito, stage takes anywhere from two weeks to several months depending on the weather. The warmer the weather the faster the development.

The importance of temperature:
While the larva are developing within the mosquito, the temperature MUST remain above 57 degrees Fahrenheit at all times, day and night. If at any time during the mosquito stage the temperature drops below 57 degrees F, the development is halted and it must start all over again. It is only the L3 larva which are capable of infesting your dog.

So, now let’s say that a mosquito has bitten an infested dog and the temperature has remained above 57 F for a minimum of 14 days since that bite and the mosquito bites your dog. Still your dog is not infested because the L3 larva are deposited in a tiny droplet of mosquito saliva adjacent to the bite not actually injected into your dog as many would have us believe.

Providing the humidity and temperature are such that the droplet does not evaporate, the L3 larva must then swim through the droplet of saliva and into the mosquito bite, thereby entering your dogs system. Once inside your dog the L3 larva must spend the next two weeks or so developing into the L4 larva. During this period of time the larva is living in the skin, not the blood of the newly infested dog. The L4 will continue to live and develop in the skin for the next three or four months where it will finally develop into the L5 stage.

Once it makes this development into the L5 it then leaves the skin and enters the circulatory system. The L5 or young adult then migrates to the heart and pulmonary arteries. Once there it will mate approximately 5 to 7 months after entering the dog’s body. That is of course assuming that the dog has been infested with both male and female larva. This mating produces the Microfilariae.

I practiced for seven years in the Santa Cruz, California area, and treated many dogs with heartworms. The only dogs that developed symptoms of heart failure were those that were being vaccinated yearly, eating commercial dog food, and getting suppressive drug treatment for other symptoms, such as skin problems. My treatment, at that time, consisted of switching to a natural (that is, homemade) diet, stopping drug treatment whenever possible, and eliminating any chemical exposure, such as flea and tick poisons. I would usually prescribe hawthorn tincture as well. None of these dogs ever developed any symptoms of heart failure.

     I concluded from this that it was not the heartworms that caused disease, but the other factors that damaged the dogs’ health to the point that they could no longer compensate for an otherwise tolerable parasite load. It is not really that different from the common intestinal roundworms, in that most dogs do not show any symptoms. Only a dog whose health is compromised is unable to tolerate a few worms. Furthermore, a truly healthy dog would not be susceptible to either type of worm in the first place.

{ 1 comment… read it below or add one }

Michael Plotkin July 2, 2014 at 2:59 am

I believe you are wrong that a temperature below 57 degrees F will reset the life cycle. As Knight and Lok, 1998 (the paper most people cite on this issue) says,
“For development to even begin, a threshold of 57°F (14°C) must be exceeded. Larvae withm the\ mosquito are more cold tolerant than the intermediate host itself. Consequently, when the ambient temperature is below the developmental threshold, maturation will be only temporarily suspended until warmer conditions resume.”

Also more recent research has shown that in regions where HDU is reached every seasaon (nearly everywhere), temperature alone does not predict transmission rate.


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