Published On: Mon, Oct 7th, 2013

Chemical Insect Repellents

dogmosquitoChemical Insect Repellents

Are They Causing Catastrophic Diseases 

In Our Pets?

by Al Plechner, DVM, and Michelle Cunningham


When mosquito season arrives, the disease they may bring might be dangerous for your dog. Our veterinarians believe that for us to keep our animals safe, we must provide our pets with monthly chemical insect repellents. In those regions, where mosquitos may cause heartworm disease, annual heartworm testing and a monthly chemical preventative is usually prescribed, but the real question is “are these chemical products really safe?”

After my own dog [referring to Michelle’s dog, Shasta] was diagnosed with SARDS (Sudden Acquired Retinal Degeneration Syndrome), only a month ago, and receiving the news that the cause of this onset of blindness is currently unknown with no known treatment, I began my quest for answers. 

I was referred to an Ophthalmologist in my area where my dog received an ERG (electroretinogram ), confirming the fact that Shasta indeed had retinal degeneration. The Ophthalmologist did not want to give me false hope that her eyesight would return, but she did mention the fact that in one of her cases, she had successfully reversed vision loss in a dog that had been taking heartworm medicine containing Ivermectin.

Because my own dog was due for preventative heartworm medicine, I decided to research this medication myself. I found the ingredients contained not only Ivermectin, but also contained many other very questionable chemicals. I thus decided to investigate and research all the chemical ingredients contained in every prescribed monthly heartworm, tick, and flea prevention medication.

To my surprise (and horror), what I found were several studies showing that many “every day” chemical insect retardants contained many of these chemicals that are not only dangerous for causing many other health issues, but may have caused blindness in my Shasta. These chemicals have also caused blindness in certain other specific canine breeds.

According to the Journal of American Veterinary Medical Association, there is a case in which two dogs that had Ivermectin in their systems also experienced sudden blindness. They both made a full recovery after cessation of exposure to the ingredient, (JAVMA, 2008). At first, it appeared that only dogs of certain breeds, such as Collies and other herding dogs, were susceptible to this sudden illness and were categorized with having a mutation in the MDR1 (multi-drug resistance) gene.

A second study, according to the Journal of Veterinary Emergency and Critical Care Society, indicated that a Jack Russell Terrier experienced blindness after exposure to Ivermectin. The dog was given intravenous lipid (IVL) therapy which reversed his condition. This was the first case reported of successful treatment of a dog with this condition that had tested negative for the MDR1 gene mutation, (VECCS, 2013).

These case studies were very helpful in proving that Ivermectin, possibly used in conjunction with other chemicals, did cause blindness in dogs. However, they did not prove that they caused my dog Shasta to also develop a kind of blindness called SARDS, but it was definitely worth forging on with my research.

After collaborating with Dr. Alfred Plechner, DVM, discoverer of the Plechner Syndrome and an expert on SARDS treatment, we started to research all of the ingredients in all of the different brands of heartworm, tick, and flea medications. For more information on Plechner’s Syndrome and on SARDS, please go to

The third case we found, according to the Australian Veterinary Journal, involved three dogs that were given oral Imidacloprid and Moxidectin at different dosages that experienced varying degrees of ataxia, paresis, hypersalivation, disorientation, and muscle tremors. Two of the dogs experienced temporary blindness. All three dogs tested negative for the MDR1 gene mutation, (Aust Vet J, 2009).

As we continued our research, we found an article by Wendy C. Brooks, DVM, DipABVP, involving Spinosad, an ingredient contained in some flea control medications. Brooks describes how the ingredient works and why it was invented in the first place. She also mentions that the drug is said to be safe to use, in conjunction with all other flea and heartworm preventatives, but then her following statement says that Spinosad can increase the risk of Ivermectin side effects, (Brooks, W., 2008).

This obviously was another concern that needed to be realized and probably avoided!

Dogs that have a deregulated immune system, dogs with this special gene mutation, and dogs taking both a flea preventative and a heartworm preventative at the same time, may be much more susceptible to the side effects of these chemicals. Blindness has been proven to be one of these side effects!

So how does my dog Shasta respond to these various chemicals?

She is Alaskan Malamute/German Shepherd mix, with a suspicion of some Collie. She has a deregulated immune system and has tested positive for Plechner’s Syndrome, and she also has been orally administered the aforementioned medications.

How do you know if your dog has a deregulated immune system?

You can have a simple blood test done on your dog or cat, referred to as an EI1 test (endocrine immune test # 1). The only veterinary laboratory doing this specific testing is the National Veterinary Diagnostic Laboratory. All and any information you may need can be found at under the heading of Get Help.

If the immunoglobulin (antibody) levels are deficient, it means that your dog is not creating enough antibodies to fend off disease and illnesses. If your dog’s mucous membrane antibody, referred to as IgA, is below 58, your dog will not be able to absorb nutrients, vitamins, medications and other supplements. The low IgA level will definitely cause a state of malabsorption which will further weaken those organs that produce those hormones that regulate the immune system.

Often the thyroid hormones (T3 and T4), are also deficient with Plechner’s Syndrome, and their receptor sites are blocked by other hormone imbalances.

Please keep this information in mind as you read on.

New research from the Australian Pesticides and Veterinary Medicines Authority shows that the ingredient Fipronil, contained in some flea control medications, has induced skin reactions in some dogs and cats. Although these incidences are few, yet occurs in your pet or my patient, one reaction is one too many! This is a concern for dogs because they may develop signs of skin allergies, alopecia, erythema, acute moist dermatitis, and pruritus. Embedded in this 138 page report, the thyroid function test results indicated that Fipronil, at some level, will decrease the production of T3, T4, and TSH (thyroid stimulating hormone), (APVMA, June 2011). This didn’t alarm the researchers, but it’s a major component of Dr. Plechner’s theory on adrenal exhaustion and the alarming effects it has on not only animals, but on humans as well.

Please imagine what might occur in the system of a human or animal with depressed T3, T4 and TSH?

The entire metabolism of the body is now depressed, and any toxin that enters the body cannot be broken down because of the slow metabolism of the liver and slow excretion rate of the kidneys. Once any of these chemical insect retardants are administered and not properly broken down, the residue that remains added to the next monthly dose of chemicals, will only become an overdose. If this overdose is caused by either the use of Fipronil or by Plechner’s Syndrome, you can expect some unhappy side effects to definitely occur.

Unfortunately when this happens, the side effects these chemicals may have caused can remain permanent, including blindness, but hopefully not. The longer it takes to stop using these damaging chemicals, the greater is the chance there is for permanent damage to occur!

Plechner’s Syndrome also deals with the detrimental effects of elevated levels of estrogen, and it is a known fact that Flea shampoos, flea collars, and most anti-flea products contain a form of estrogen referred to as xeno-estrogens which can definitely be harmful.

NOTE: Just for your own edification, there are more than 70,000 chemicals, including every day house hold chemicals, that make up various products and hand soaps that also contain xenoestrogens. (It may be worth your while to Google “xenoestrogen” for further protection of yourself, your family, and your family pet or pets.

Another reason why chemical insect retardants may create side effects is due to the Mutated MDR1 Gene.

The breeds that are affected by this gene are Australian Shepherds, Border Collies, Collies, English Shepherds, German Shepherds, Herding Breed cross, Long-haired Whippets, McNabs, Mixed Breeds, Old English Sheep dogs, Shetland Sheep dogs, and Silken Wind hounds, (Eldredge, DVM, April 2013). This gene mutation prevents the dog from metabolizing certain drugs even at a safe level. You can imagine how any reduced thyroid function would further compound the problem even more.

Although it is dependent on the quantity of the dosage and even if given a reduced dose of these specific drugs, these dogs can experience severe and even deadly side effects if given the following drugs: acepromazine, butorphanol, doxorubicin, erythromycin, ivermectin, loperamide, milbemycin, moxidectin, rifampin, selamectin, vinblastine and vincristine. Heartworm medications specifically have significant levels of Ivermectin and milbemycin in their formulations.

If your dog is not one of the breeds susceptible to this gene mutation, there is still risk of severe side effects to Ivermectin, as shown in the second case discussed, as well as to Imidacloprid and Moxidectin, as shown in the third case. I will also include Spinosad* with an asterisk, because it clearly states that if given in conjunction with Ivermectin, it can make the dog sensitive to Ivermectin’s side effects.

Last, but not least, Fipronil seems to be safe except for the fact that it suppresses thyroid function, which may lead to a deregulated immune system causing malabsorption. If you haven’t read about the Plechner’s Syndrome, please do so in order to understand the seriousness of the effects of Fipronil found in flea and tick preventatives, including all those unhappy chemicals that are prescribed daily for insect retardation; but is it really, or is it really a retardation of your pet?

Before ever exposing your pet to any of these chemicals, it might be worth making sure your pet does not have Plechner’s Syndrome.

The value of checking this syndrome often comes from a preventative standpoint because an imbalance of this syndrome may identify the cause of allergies, autoimmunity, cancer, and why certain environmental exposures cause problems when they should not!

The purpose of this article is to inform you about the dangers of using chemical heartworm, tick, and flea repellents. The use of these monthly chemicals might be convenient for you as the pet owner, but they could be deadly for your pet.

The links listed below are for your further information on the damaging effects that these heartworm, tick, and flea chemicals could cause and the side effects they may also cause your pet.

Please consult with your veterinarian for safer alternatives and educate yourself as to when an insect repellent is or is not indicated for use in your part of the country. Please try to minimize the use of any chemical.

Above all, always “read the label!

Please think this way; if you would not use a specific chemical on yourself nor on your family, then why would you consider using it on your pet?



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