Heartworm is a spine-chilling word for dog owners.
Every veterinary clinic has gruesome photos on the walls. The ones with foot-long spaghetti-like worms in a dog’s heart …
And you’re warned … if you don’t want your dog to end up with dreaded heartworm, you’d better give her monthly preventive heartworm drugs.
Preferably year round.
Conventional vets are afraid of heartworm because they’ve seen how difficult and risky heartworm treatment can be.
So they want to scare you into buying the heartworm preventive drugs … and they’re often successful.
Even holistic vets want you to take heartworm meds.
So your dog needs them, right?
Well, I’ll let you decide ..
Here are 10 things you probably don’t know about heartworm.
1. Who Sponsors The American Heartworm Society?
Visit the American Heartworm Society (AHS) website and you’ll find pages of information on heartworm disease and dogs (including more of those sickening spaghetti pictures).
They’ve got brochures, maps, infographics and even children’s games to teach you about the risks of heartworm disease. And there are all kinds of resources that veterinarians can use to improve “compliance.”
While that seems generous, it’s really designed to get you to buy heartworm meds.
And give them every month, year round. Even in cold climates.
Probably because the people behind the American Heartworm Society are the people who make heartworm meds.
Check out this list of sponsors:
This is called CONFLICT OF INTEREST.
These large companies have a vested interest in giving you as much information possible to convince you to buy their drugs for your dog.
They even state that “No natural or herbal therapies have been shown to be safe and effective prevention or treatment for heartworm disease.”
If you think this is true, jump ahead to #9 (hint: it’s blatantly untrue).
2. Heartworm “Preventives” Are Not Preventive
The so-called heartworm preventive drugs don’t prevent your dog from being infected with heartworms.
Instead, they work by killing heartworm larvae that may already be in your dog’s body. So heartworm meds are actually treatment drugs, not preventives.
And if your dog hasn’t been infected, you’re treating her for something she doesn’t even have.
When you give your dog monthly heartworm “preventives,” what you’re really doing is poisoning the heartworm larvae before they grow into adult heartworms.
Why is that a problem?
3. Heartworm Meds Are Neurotoxic
Heartworm meds are pesticides.
Just the idea of putting pesticides into your dog should make you hesitate. And when you learn how those pesticides work, you’ll really think twice.
The drugs are neurotoxins … the way they work is by paralyzing the parasites’ nervous systems.
Wonder what effect that might have on your dog?
The Adverse Drug Experience (ADE) reports on the FDA (Food and Drug Administration) website will show you the side effects reported in dogs.
And they’re conditions that involve the nervous system. Things like:
- Ataxia (staggering/incoordination)
4. Heartworm Drugs Are “Safe” For Your Dog
But not for you!
The warning labels on heartworm medications are very clear …
If you or your child accidentally gets heartworm meds inside you, you need to rush to the doctor immediately.
Here’s the warning on the label of Heartgard, one of the most popular heartworm drugs:
So these drugs are perfectly safe for your dog to eat … but call the poison control center if you eat them!!
Yet you vet will tell you heartworm meds are “safe” for your dog.
Even when taken every single month, year round.
I’m not aware of any long term clinical studies done on the safety of these drugs.
But we know there are serious side effects reported every month … and that includes death!
Still think heartworm meds are safe for your dog?
Even if they were relatively safe, here’s something else to consider …
5. It’s Not So Easy For Your Dog To Get Heartworm
Heartworm disease is transmitted by a mosquito bite. But it’s not quite that simple.
For your dog to get infected, here’s what has to happen.
First of all:
- Heartworm is spread only by certain breeds of mosquitoes (not all breeds can transmit heartworm)
- To be a heartworm carrier, the mosquito must bite an infected dog or other animal
- Dogs can’t catch heartworm from other infected dogs – it can only come from an infected mosquito
Then, there are several other things that have to happen for your dog to get heartworm disease:
There are several studies showing that the weather must be warm enough for heartworm larvae to develop in the mosquito.
The University of Pennsylvania vet school found that “Below a threshold temperature of 14C (57°F), development cannot occur, and the cycle will be halted.”
The dog (or other host where the mosquito picks up the heartworm) must already be infected with mature male and female heartworms.
And they must have produced microfilariae that are alive when the dog is bitten and are at the site of the bite.
Now, a female mosquito needs to bite the animal carrying these microfilariae.
Only female mosquitoes can act as an incubator for the microfilariae to grow into the mature larvae known as L3.
This takes 10 to 14 days and again, it requires the right temperature.
The female mosquito that is actively incubating microfilariae needs to bite your dog to transmit heartworms.
And the temperature and humidity need to be high enough for the mature L3 larvae to make it through your dog’s skin.
Many studies say this requires a steady daily temperature of at least 64°F, day and night for a month for this to happen, and if, at any time, the temperature drops below 57°F, the maturation cycle will fail and the female mosquito can no longer transmit heartworm to dogs.
So mosquito bites don’t give your dog heartworms …
It has to be a female mosquito. One that’s bitten another animal that was carrying microfilariae. And the temperature has to be warm enough.
Heartworm isn’t as easy to get as you think. Plus …
6. Heartworm Isn’t Everywhere
The AHS recommends year-round medication for dogs, no matter where you live.
They say this because there are heartworm cases in all 50 US states.
But have a look at this AHS map of heartworm incidence in 2016 (the most recent map published up to 2019.
Those white parts experienced less than one case per clinic.
And the pale pink areas only have 1 to 5 cases per clinic.
On average, more than half of the US gets fewer than 5 cases of heartworm per clinic.
Is that really enough risk to justify giving your dog a poisonous pesticide every month … one that could cause him to become seriously ill or even die?
And there’s another problem with regular heartworm med use …
7. Heartworm Drugs Are Becoming Less Effective
Heartworms are becoming resistant to heartworm drugs.
In December 2013, the AHS reported that, in certain areas of the United States, a large number of dogs have become infected with heartworms while taking heartworm meds.
What does the Heartworm Society say we should do about heartworm med resistance?
Give more heartworm meds, of course!
If a drug doesn’t work, why give more of it and create more resistance?
And this reduced effectiveness leads into the next point …
8. Drug Manufacturers “Guarantee” Their Products …
… but good luck collecting.
They don’t make it easy.
One company, Zoetis, which makes Revolution, says,
“If any dog determined by a licensed veterinarian to be free at the onset of treatment with Revolution develops heartworm disease, we will provide reimbursement (up to $750 and the acquisition cost of melarsomine dihydrochloride) associated with the diagnosis and treatment of heartworm disease and provide a year’s supply of Revolution.”
Oh good, a year’s supply of the product that didn’t work!
But in order to pay the guarantee, they require:
These are pretty stringent requirements and other heartworm med manufacturers have similar standards.
How do you prove the first point, that you gave Revolution at all times according to label directions? Your dog is your witness!
So, if you use these drugs and your dog gets heartworms, it’s unlikely you’ll be able to collect under the guarantee.
9. Immiticide Isn’t The Only Treatment Option
One of the reasons vets want you to use heartworm meds is because the treatment they use is dangerous and difficult for the dog.
The treatment involves a series of injections with a drug called Immiticide (melarsomine) over a period of three months.
During this treatment, your dog has to be on crate rest and restricted exercise.
This is because dead heartworms can travel to your dog’s bloodstream, which can be fatal.
And the treatment isn’t always effective either.
In fact, ineffectiveness is the first of many side effects reported.
Here’s the first page of the ADE for merlarsomine from the FDA website:
If this is true, why does the AHS want you to only use veterinary-approved treatments?
Oh yeah … because the sell them.
There are actually several natural treatment options that are much gentler on your dog and don’t require restricted activity.
- Over the counter herbal blends with a good track record
- Homeopathic treatment through your homeopathic veterinarian
- Black walnut and wormwood: there are various protocols using these herbs. They are very powerful and can be toxic if used improperly, so use them only with guidance from your holistic veterinarian or herbalist.
Here are more details about natural treatment options you can try at home or with your holistic vet.
If the thought of preventing heartworm with herbs scares you, consider this …
10. Wild Dogs Don’t Get Sick From Heartworm
It’s true. Wild canines like wolves, coyotes and foxes don’t seem to get sick or die from heartworm disease.
In a Wisconsin study from 1991 to 1996, researchers captured and tested adult wolves for disease.
Only 2% of wolves had any trace of heartworms.
Another study in Illinois tested 920 coyotes caught by hunters from 1995 to 1997.
Only 16% had any incidence of heartworm.
Even the coyotes who had heartworms weren’t sick. Their body weights and fat reserves were unaffected.
Think about that …
While wild animals are outdoors 24/7, they have a much higher risk of being bitten by mosquitoes.
So why are dogs more susceptible to heartworm disease?
- Vaccination or over-vaccination
- Poor nutrition
- Exposure to toxins like drugs, pesticides, fertilizers, household cleaners, and other chemicals
Every drug, chemical and vaccine your dog is exposed to compromises her immune system.
Even the AHS admits, “Host immune responses affect the presence of circulating microfilariae.”
In other words, your dog’s immune system can kill the microfilariae without meds.
In fact, special antibodies called IgE are a part of the immune system that are responsible for finding and attacking parasites like heartworms.
So why would you reach for heartworm meds that can harm your dog’s immune system?
What Can You Do For Your Dog …
The immune system is key to helping your dog prevent heartworm.
Here are some things you can do to help strengthen your dog’s immune system:
- Feed a fresh, whole food diet
- Minimize vaccines
- Avoid prescription drugs like antibiotics or non-steroidal anti-inflammatories (NSAIDs)
- Avoid chemical pest control products (like spot-on products) and dewormers
- Don’t use pesticides or herbicides on your lawn
- Use natural cleaning products in your home
- Avoid heartworm meds!
Take these 10 facts into consideration before deciding how to protect your dog from heartworm.
You can learn more about heartworm disease in this article.