On Heartworm…

I wanted to re-post Dr. Siri Dayton’s truly excellent emails on the subject of heartworm that she wrote for the SFRAW Yahoo Group in 2009. I concur with her suggestions wholeheartedly.


I have had dogs my entire life and have never once given any of them heartworm medication in any form; and I’ve never had a pet test positive. While San Francisco and the Bay Area are not areas with a lot of heartworm disease, whenever I visited heartworm endemic areas with my dogs (camping in the Sierra foothills or Russian River area, for example), I’d test them when I returned and then again 6 months later. The plan was if they tested positive at an early stage, we would then dose them with Ivermectin at that time only. I never had to do that because they were always negative.


I would personally never use Heartguard as recommended conventionally. But I wouldn’t use Black Walnut preventatively either. However, this herb might be the better option for someone living in a heartworm endemic region, if their dogs live outdoors and get bitten by mosquitoes frequently.


Whenever I went to areas with a lot of mosquitoes (even in San Francisco) I’d spray myself and the dogs with my Tick Spritz and that worked well to deter the bugs enough to not get eaten/bitten. While Tick Spritz was part of my heartworm prevention program, I didn’t live somewhere where mosquitoes were everywhere all the time — just bad in certain parks, at certain times of year and times of day. That made use of such a topical pretty easy. I know this is not true for people living in areas with a lot more bugs.


Hope this helps!




Heartworm Prevention (PART I)

Originally posted to SFRAW Yahoo Group December 2009


This is a topic of great concern to dog owners so I thought I would

chime in here and clarify a few conventional basics about Heartworm

disease, prevention, and treatment.


Heartworms are transmitted to dogs through infected mosquitos who

carry heartworm larvae. If an infected mosquito bites your dog, it can

pass the larvae to your dog.


For those of you who choose to treat their dogs:

  1. Heartgard is the most commonly used product on the market for the

prevention of heartworm disease. The drug in it is ivermectin. As one

other person mentioned, ivermectin is a common cattle dewormer and, if

your vet is able and willing, you can get it very cheaply this way.

Ivermectin is toxic to sight hounds. Though some veterinarians purport

that the extremely low dose of ivermectin can be given safely to sight

hounds, I would avoid that drug altogether (why push your luck?) and

use an alternative product called Interceptor (milbemycin) for sight



  1. The package instructions for Heartgard suggest giving the product

once a month. However, studies clearly show that the drug is close to

100% effective for longer than that. It can safely be given every 6

weeks IF you can keep to that schedule. In careful studies, dogs who

become infected with Heartworm disease while on Heartgard have

invariable received their dose late or have missed doses (or have

vomited it up).


  1. In our area of California, mosquitos are out and around all year

long. It has to be consistently lower than thirty something degrees

before mosquitos die, so it is unwise to skip the winter months here

in the bay area.


Diagnosis and Treatment:

  1. It is recommended that dogs who are not on heartworm prevention be

tested for heartworm disease once a year. I recommend this even to my

homeopathic clients (though I confess I have not tested my own dog in

over 3 years). If a dog does become infected with heartworms, the

sooner you know about it, the less damage they will do and the easier

and more successful the treatment will be. For those dogs who are on a

preventative product, a conservative recommendation is to test every

other year. Dogs who take Heartgard religiously have essentially no

chance of contracting the disease. Vets recommend every other year

testing because we pick up positive dogs – again, this happens when

doses are missed. If you are VERY certain that you have given the

doses every 6 weeks religiously, you should not need to test.


  1. Treatment with conventional drugs is not nice. As someone else

commented, the drugs themselves are very toxic. And, depending on how

many worms a dog has, when the worms themselves die, there can be

serious complications. I treated several dogs in my conventional

practice. Thankfully, all survived but it is not a nice or easy path

for anyone involved.


That is what I was taught in vet school and what is (or should be)

recommended by conventional vets out there. I no longer practice

conventional medicine, so this is no longer what I recommend for my



Heartworm Prevention: A Holistic Approach (PART II)


Having put my white doctor’s coat on for you all briefly the other day

to clarify the conventional aspects of heartworm disease in dogs, I

gladly shed that old starched coat and tell you what I now recommend

to my clients from the perspective of a homeopathic veterinarian.


First, one correction to my previous email. A member pointed out that

ivermectin (the drug in Heartgard) is toxic to Collies. I had this

wrong. Sight hounds have no increased sensitivity, it’s just Collies.

Sorry about that, and thanks to the person who pointed that out!


Now, on to a more natural approach to heartworm prevention. It will

help to understand first how heartworm disease functions in the

natural world. To see this, we look to wolves, dogs wild equivalents.

In the wolf population, heartworms exist at a low level (7% of wolves

according to a good study). Importantly, of those wolves who were

affected, none of them showed signs of health problems from the



In our domesticated, “well cared for” dogs, heartworm infection does

exist and in higher percentages than in wolves. Why is this? Dogs and

wolves are essentially the same genetically, so species difference

does not account for the increased susceptibility in our dogs. What we

know about parasites (intestinal worms, fleas, heartworms, etc.) is

that inhabit weak animals, animals with compromised immune systems.

The immune system is an incredibly powerful, effective tool our bodies

have to fight disease. But it is also very fragile and requires

nurturing and respect to keep it functioning properly. The simple,

highly effective strategy is to do everything we can to strengthen our

pets’ immune systems, and to avoid as much as possible those things

that weaken the immune system.


Here is a shot at a list of things you can all do to improve your

animals’ lives immensely.


  1. Diet: Feed fresh, whole food diets!!!! Do everything you can to

come as close to a 100% fresh diet of natural or organic high quality

foods. Kasie is nothing less than a guardian angel for all of our

animals in making this truly possible between her incredible knowledge

of nutrition and the work she does to make such a wide variety of

meats and other whole foods available to all of us.


  1. Vaccinations: In my opinion, the widespread over-vaccination of our

domesticated animals has led to a serious decline in health. This is a

whole lecture in itself, but the assault on an animal’s immune system

can be very damaging, creating a weakened animal whose susceptibility

to immune diseases increases significantly. So, vaccinate wisely.

Avoid vaccines for diseases that are not life threatening, avoid

vaccinating for diseases that are not prevalent in your area, and stop

the madness of repeating distemper/parvo vaccinations year after year.

Educate yourselves and don’t just follow the advice of veterinarians

who still recommend yearly distemper boosters. Even the strictest

conventional research out there shows that this is unnecessary and

potentially damaging to your pet’s health.


  1. Lifestyle: The way most of us keep our pets (myself included) is

highly unnatural and stressful for them. Do everything you can to

provide lots of exercise, fresh air and mental stimulation. Poor

“husbandry” should not be underestimated as a source of illness. I

suggest that all of you read Temple Grandin’s latest book, Animals

Make Us Human for an important and illuminating understanding of



  1. Toxins: Our world is full of them. Animals (and especially cats)

are very sensitive to chemicals. Practical things you can do include.

  1. Provide fresh filtered water (if you can afford it, get a

filtration system that removes fluoride along with other bad things).

  1. Use mild, natural cleaners in your house. It is disheartening to

walk down the cleaning isle in the grocery store and see the shelves

of extremely toxic substances when vinegar, baking soda and a few

other innocent things are equally effective.

  1. Stop using pesticides to control fleas and ticks as much as

possible. Pesticides are poisons. Instead, do what you can to improve

the health of your pet and the fleas will leave them alone!

  1. Drugs themselves can be very toxic to your animal. We are a drug

crazed society (though France is worse, I recently read), thinking we

need to treat every little ailment with strong drugs. Seek milder

treatment alternatives when possible.

  1. Consider consulting with a Classical Homeopath or someone trained

in Traditional Chinese Medicine to help you get chronic problems under

control, and to help you find your way through these very confusing



  1. Support the immune system with all the measures above, and also

with a product like Transfer Factor Plus, Canine or Feline Complete

Formula. What we understand about transfer factors is that they are

able to balance or modulate the immune system. So, if the immune

system is compromised, it increases the ability of the immune system

to respond (this is KEY in fighting off foreign invaders such as fleas

and heartworms!). If it is over reacting (as in allergies, auto-immune

diseases, etc), transfer factors slows it down.


Finally, it may help if you understand that most of conventional

medicine feeds off of our FEAR. Vets and doctors scare you silly about

the dangers of heartworm disease, driving the point home by showing

you a heart filled with worms in a formalin jar before selling you a

package of expensive drugs to prevent this happening to your little

dog. I know. I used to be one of those vets.


In that past years, my understanding of health and sickness has

shifted dramatically. I have learned to trust the immune system. It is

an excellent system, far better than any drug or treatment that

exists. I do not recommend heartworm preventative for the vast

majority of my clients. There. I said it. I stand behind my word too.

Of course, I cannot offer a money back guarantee that your animal is

not going to contract heartworm disease, but I have colleagues who

practice using these methods in states like Texas and Florida where

heart worm disease is rampant in the dog population, but who have not

seen a positive case in their patients under homeopathic care for over

20 years. Those are better results than I saw in over 10 years of

conventional practice, and should be very compelling to you.


So, the best advice I can give you is to stop acting from fear, and

start taking substantial steps to improving your dogs health.



I wish you all healthy and happy holidays,


Siri Dayton, DVM


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