Heartworm Season & Treatment

Heartworm season – minimize the toxins you use to prevent heartworm! 

When mud season arrives, mosquitoes are not far behind. We’ll soon be seeing a postcard in the mail from our local vets, reminding us to get our dogs tested for heartworm. In many cases we are also reminded update our dog’s “yearly” vaccinations. If you see a mosquito, is it time to use preventive medication?  

Minimize toxins to help your dog live longer! 

Minimizing toxins is one of the foundations of our “Live Longer” program. Use only those medications, preventatives, and treatments that are useful and necessary. With careful evaluation, some “approved toxins” may be avoided. Medications are by their nature toxic to certain organisms, and often have serious short or long-term side effects for the animal. 

Sometimes chemicals are necessary to save lives. The chemicals used to prevent heartworm are extremely effective and can save dogs from difficult, unpleasant, and potentially dangerous treatment. However, many veterinarians recommend treatment schedules which result in far greater quantities of toxic chemicals being ingested by dogs (and cats) than are necessary or even advised by the American Heartworm Society. 

Heartworm Facts 

The transmissibility season for heartworm varies by climate, and is determined by temperature. In order for the larvae of the heartworm, carried by mosquitoes, to be transmitted to a dog, the temperature must be at least 60 degrees for a month. 

This means, for example, that in Florida, the heartworm season will be quite long. In Florida, it might make sense to give preventative year round. 

In Chicago, the temperature necessary for transmission is not usually reached at night until June. The beginning of the season is not likely to be earlier than June 1 most years, and perhaps later, even through mosquitoes may be present. Temperatures begin to drop at night by September. By October, the season will certainly be over, though we may still see mosquitoes. 

Preventatives kill heartworm larvae. The chemicals used to control heartworm are called preventatives, but when we use them we are actually treating larvae: the chemicals kill the larvae your dog may have picked up in the period since the last dose.  

Prevention Options: Drugs used are “daily” (Diethylcarbamazine Citrate, DEC) to “monthly” (Ivermectin: “Heartgard”, “Iverheart”; and Milbemycin, or “Interceptor”, and Selamectin, “Revolution”). A 6-month treatment (Proheart) was pulled from the market after numerous adverse effect incidents, including deaths.  

The daily preventative (DEC) was once the only choice.

It is not easy to find since the introduction of Ivermectin and other “monthly” treatments. It’s quite effective, and many feel that it is easier on the body. However, if DEC is given to a dog that is already heartworm positive, anaphylactic shock may result, and death. Completing a heartworm test prior to giving any heartworm medication is imperative. Two other issues keep us using the “monthly” preventatives vs. the daily medication. 

Some dogs stash pills away in their mouths and dispose of them where you can’t see them. You must be sure that the dog is swallowing them. Heartworm medication must be swallowed to be effective! 

Also, humans must remember to give daily preventatives. Missed doses may result in infection. This is how two of our dogs contracted heartworm. While May survived the arduous treatment, her brother was blinded. Too bewildered to make the adjustment, he was euthanized. That was long ago and treatment protocols have improved vastly, but treatment is still very toxic to your animals. We prefer providing regular oral preventative medication to the harsh reality of treating a heartworm positive dog.  

“Monthly” treatments are best kept as simple as possible.

There are a number of options based on several chemicals. You have a choice of a pill (flavored or unflavored) or a topical treatment. Some formulations are “multipurpose”. 

We prefer that dogs only receive medication that specifically prevents heartworm, rather than a combination that treats for multiple problems (which your animal may not have). Some manufacturers formulate products that combine heartworm prevention with worming medication, flea, tick and mange medication, just in case your dog may encounter these parasites.

“Just in case” is not a good enough reason to put a multitude of toxic chemicals into your dog’s body. Chemicals are hard on the body, and they interfere with good gut ecology. Plain Ivermectin (Heartguard) is the simplest choice, and the safest for most dogs. Some breeds have shown sensitivity to Ivermectin. We recommend you discuss the least toxic options for your animal with your holistic veterinarian.  

Make sure your dog swallows the pill! Keep an eye on her for a while afterward. While it doesn’t happen often, dogs occasionally vomit pills.  

When to start and end medication? 

To determine the best time to test your animal, see the guidelines at heartwormsociety.org. Each geographic area is different. You’ve had your dog tested this spring, and she’s clear of heartworms. How do you know when to start the preventative? 

Heartworm is not transmissible from mosquitoes to dogs until the weather is quite settled and warm, and the medications work on larvae acquired after the season starts. The time to start recommended by the American Heartworm Society is a month after the transmissibility season begins. 

The chemicals used for “monthly” prophylaxis are effective for at least 6 weeks. Many treatment protocols recommend one-month intervals year round, to account for missed doses and client (that’s us) unreliability. The concern of veterinarians that administration will be incomplete is valid. It’s true that humans may fail to give sufficient attention to the date. However, it’s easy enough to write on your calendar the dates that medication is due, to save your dogs unnecessary chemical exposure. 

Holistic veterinarians often recommend that the first dose be given a month after the season begins (dealing with any larva which may have been acquired and allowing for a little overlap) and every six weeks after that, until the end of the season. The Heartworm Society recommends that the last dose be given within a month after the season ends.  

How many doses are you likely to need? In a normal Chicago spring, four: July 1, August 15, October1, and Nov 15. Even if you are extra conservative, no more than one more dose will be needed. If you start May 15, you’ll end October 1. Few Octobers in Chicago have nights above 64 degrees, but if this occurs, one more dose would be needed before the end of the season. Close attention to the weather, particularly night temperatures, will give you excellent information about when to start. 

Are there other options to keep your dog heartworm free? 

Some concerned dog caretakers have sought out more “holistic” and “natural” options such as herbal or homeopathic remedies. If you desire to not use traditional heartworm medication it’s imperative that your animals be under the care and supervision of a veterinarian with expertise in this area. If you use these options and your animal does not contract heartworm, that doesn’t prove that “it works”. It just proves that your dog didn’t get heartworm.  

Holistic veterinarians suggest supporting the liver after treatment. 

Chicago area holistic veterinarian Karen Shaw Becker suggests a daily dose of milk thistle for the week following each treatment. Milk thistle supports the liver as it metabolizes the medication and aids in the body’s detoxification processes.  

Our goal is to minimize our animal’s exposure to chemicals. 

We recommend supplying the smallest amount of a chemical treatment that will do the job, for the shortest time period possible. This balance provides the best solution to a major health threat, with the minimum amount of medication, followed by appropriate detoxification.  

Of course, the support of a whole food diet and an active and stimulating life will also help your dogs live long healthy lives!  

What about cats? 

In the past few years, veterinarians have begun to recommend that cats receive chemical preventatives for heartworm. This article is addresses heartworm prevention for dogs only. Cats are not the natural hosts of heartworm. The incidence of feline heartworm causing clinical disease is very low compared to dogs. Bear in mind the actual risk that your cat will encounter mosquitoes when making a decision about medication: for most cats this risk is extremely low.

For more detailed information on all aspects of Heartworm, go to http://www.heartwormsociety.org.         

copyright Steve Brown and Beth Taylor

See Spot Live Longer 

this article may be reproduced for educational purposes with the above credits included 


~ by abbyjokickass on November 19, 2007.

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