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Admittedly, fleas are a huge problem in Texas, especially in warmer to hot months.  The FDA finally put out a warning in 2018, stating, “The U.S. Food and Drug Administration is alerting veterinarians and pet owners of the potential for neurologic adverse events in dogs and cats when treated with isoxazoline class flea and tick products, including Bravecto, Nexgard, and Simparica. Data received by the agency as part of its routine post-marketing activities indicates that some animals receiving Bravecto, Nexgard, or Simparica have experienced adverse events such as muscle tremors, ataxia, and seizures, said the FDA in a statement. Credelio, another isoxazoline class product, recently received FDA approval.” But did they go far enough by issuing this warning? In my opinion, the answer is NO! Because of the number of dogs that have either been harmed or died, it is my opinion that all oral flea medications, and oral heartworm flea combinations should be removed from the market.  I’m going to state my recommendations for Heartworm, Flea, and Tick prevention first, and then follow up with a history of all the other heartworm, flea, and tick preventatives that are now currently available.  

My recommendations for Flea prevention 

  1. TREAT your yard. If your neighbors don't treat their yard this will be an ongoing process. The environmentally friendly product, Diatomaceous earth does work.  It's important to understand the life cycle of the flea. If your flea problem is out of control, you will have to follow up weekly for several weeks to kill all the eggs. 

  2. If you have an out-of-control flea problem in your yard, you may have to use a harsher chemical from Home Depot to knock them down.  Just don’t allow your dog on the yard for 24-48 hours.  

  3. If you see fleas, bathe your dog with ANY pH-balanced dog shampoo. It does not have to be a FLEA shampoo (and preferably NOT).  Any shampoo will kill fleas if you lather them up and leave on for several minutes.  Dawn Original dishwashing liquid will also kill fleas, but you do need to follow up with a pH-balanced dog shampoo.  Dogs need a pH of 7 which is considered neutral.  Dawn Ultra has a pH of 7 as does Joy Ultra Concentrated and Seventh Generation Dish Liquid.

  4. “Wondercide” is a great new product whose primary ingredient is cedar essential oil. This really works. You don't need to drench your dog in it. Just follow the instructions. It's all-natural, and not expensive.  You can also use it on the dog’s bedding.  I love the lemongrass scent.  They also now make a new Wondercide collar that will last up to 4 months with a breakaway safety feature.  

  5. If your flea problem is out of control, as a last resort you can use Advantage II Topical which will kill fleas in 24 hours.  And you can dose your pet by weight. For example, a small dog’s package is for 3–10-pound dogs. If your dog is a 3-pound puppy, then only use 1/3 of the vial, and clamp off the vial for another 2 usages.  You'll notice that there is no expiration date. It is a topical insecticide, and insecticides never go out of date. Also, it claims the product needs to be applied every 4 weeks. Most of the time, you can get by only treating every 6 weeks. does have good pricing on both Advantage II and Frontline Plus. 

  6. There are also some effective essential oil-based flea collars that you can purchase.  

  7. I would like to mention that a lot of Pest Control companies that treat your yard for fleas will tell you that the products they use are safe for dogs.  This is not true, and after they spray your yard, you should keep your dog inside for 24 hours. 

My recommendations for Tick prevention: 

​ Advantage II does not kill ticks, but Frontline Plus will also get ticks.  However, it does take 48 hours for Frontline Plus to kill the fleas.  Advantage II will kill fleas in 24 hours.  If you don't have ticks, you'll want to use Advantage II, because one flea can lay 50 eggs in a day.  It does take 10 days for them to hatch.  They look like tiny black pieces of pepper/dirt.  You can see why you have to treat your yard weekly for a while to get rid of all the eggs that continue to hatch.

My recommendations for Heartworm prevention: 

Heartworm is transmitted by mosquitos, and if you live in Texas, then you have mosquitos. There are only a few areas in the U.S. in which giving a year-round heartworm preventive is advisable — those areas are in south Texas, South Florida, and other locations along the Gulf Coast. The goal is to use the least amount of chemicals necessary that successfully treat heartworm. Give the treatment at 6-8 -week intervals rather than every four weeks. Heartworms live in your pet's bloodstream, so natural GI (gastrointestinal) de-wormers, such as diatomaceous earth, and anti-parasitic herbs (e.g., wormwood, pumpkin seed, black walnut tinctures) are NOT effective at killing larvae in the bloodstream.

I only recommend Ivermectin which is (Heartgard Plus or Heartgard Plus generics). Unfortunately, you cannot divide a Heartgard Plus chewable tablet in half and only give half. They put such a tiny drop of ivermectin in a chewable tablet.  When you divide it in half the probability is quite high that one-half of the tablet will NOT contain any ivermectin.  Ivermectin is safe compared to all the other heartworm alternatives.  It is one of only a very short list of drugs that can safely be given to pregnant females. Because we live in a high-risk area for heartworm, I do not recommend any of the natural/holistic approaches to heartworm prevention.  Especially, if you live in a high-risk area for mosquitos which cause heartworms.  Because of the longer life cycle of heartworm, you only need to give Heartgard Plus every other month.  You will need a veterinarian prescription to purchase Heartgard or its generic if you are not purchasing it from his/her office.  If you have paid for an office visit, your vet is obligated to give you a prescription.  Allivet will call/fax your veterinarian for an oral prescription.  If you’re a breeder, contact me and I’ll tell you how you can save yourself a lot of money treating your breeding stock with Ivermectin 1% injectable orally vs. using the chewable tablets.

The “Plus” ingredient in Heartgard is Pyrantel Pamoate.  This is also a very safe de-wormer.  It must be added to the Heartgard because the amount of ivermectin needed to prevent heartworms is very low and will not kill other worms.  Pyrantel Pamoate is a very safe and effective de-wormer.  I use it on my puppies until they are 6 weeks of age, and then I switch to Safeguard (Fenbendazole) which also treats for Giardia.  If you have children, and they had pinworms, then they were most likely given Pyrantel Pamoate.  

Let me put all of this in perspective; a 12-month supply of Trifexis purchased online from Allivet is $240 or $20 a month.  Because you only need to give Heartgard Plus every other month, if purchasing the generic from Allivet the cost will be $1.83 a month.  That’s a $218 yearly savings for a product that is safe and effective for your dog. 

I should mention that some breeds have a gene mutation where Ivermectin in higher doses is unsafe for them.  These breeds should take Interceptor or its generic: Collie, Border Collie, Australian Shepherd, German Shepherd, Miniature American Shepherd, Old English Sheepdog, Shetland Sheepdog, and Skye Terrier.  

The History of Oral Flea Medications and

Combination Heartworm & Flea Preventatives:

Capstar: To understand the history of the oral flea medications you must go back to the very first one, Capstar, which came out in 2000. Nitenpyram is an INSECTICIDE first used in agriculture and veterinary medicine to kill off external pests, like fleas. The compound is a neurotoxin belonging to the class of neonicotinoids. Later, nitenpyram was expanded for use as an oral flea treatment by the pharmaceutical company, Novartis, under the trade name “Capstar”, with a subsequent FDA approval for non-food-producing animals in October 2000. Because we wouldn't want humans to ingest this product, BUT it's ok for dogs?


As a pharmacist, I realized that giving an oral insecticide to dogs was NOT a good idea, and since 2001, I've had it in my contract that my health guarantee was null and void if any of our pups were administered oral flea medications. Understand that there are NO long-term studies that have ever been done on the safety of giving oral insecticides to pets.  But since Pest Control workers must get tested for pesticide poisoning twice a year, common sense tells you these products could NOT be good for animals.  

Trifexis & Comfortis: The next group of oral insecticides introduced was Trifexis and Comfortis in 2011. The active ingredient Spinosad is an insecticide based on chemical compounds found in the bacterial species, Saccharopolyspora Spinosa. You can do the research, but there are petitions to take these drugs off the market due to the high incidence of deaths in dogs and cats. There WERE Facebook pages dedicated to this, for example, Does Trifexis Kill Dogs? However, Facebook took all those pages down.  I don't think that it was a coincidence that Trifexis was introduced in the marketplace in 2011, that was in fact, the same year that Heartgard went generic. 

Nexgard, Nexgard Spectra, Bravecto, Simparica, Simparica Trio, Credelio: The isoxazoline's were first introduced: Nexgard in 2013 Bravecto in 2014, Simparica in 2016, Credelio in 2018 This is what is VERY important for you to understand: Because the active ingredient, Isoxazoline, is inside your dog’s body, a flea or tick must BITE your dog to contact the chemical – no contact, no death. If your dog is flea allergic, it will still have flea allergies as it is being bitten. If you live where Lyme disease, Rocky Mountain Spotted Fever, Ehrlichia, or any other TICK disease is a concern, your dog can still be infected by these life-threatening diseases as the tick must first BITE to receive the chemical treatment. In fact, the tick may continue to be attached for 48 hours!  What is the point of killing the tick, if it has already bitten your dog and possibly infected it with Lyme disease? In September of 2018, the FDA issued an alert to all veterinarians regarding these isoxazoline medications;  “The U.S. Food and Drug Administration is alerting veterinarians and pet owners of the potential for neurologic adverse events in dogs and cats when treated with isoxazoline class flea and tick products, including Bravecto, Nexgard, and Simparica". Data received by the agency as part of its routine post-marketing activities indicates that some animals receiving Bravecto, Nexgard, or Simparica have experienced adverse events such as muscle tremors, ataxia, and seizures, said the FDA in a statement. Credelio, another isoxazoline class product, recently received FDA approval.  You can read the entire article here: Click Here

Sentinel: Sentinel (Noravatis pharmaceutical) uses yet another agricultural pesticide, Lufenuron, which is a benzoylurea pesticide. It’s enough poison to kill an army of insects and parasites. But it is FDA approved and the FDA says it is harmless to dogs. So, is it "safe" to trust the FDA when it comes to your pet? Again, the FDA legally allows dead, diseased, and rendered animals as protein sources in dog foods, because all the many dead animals would STRESS and overburden our landfills. But this is the BEST part! Lufenuron has no effect at all on the ADULT flea, as a matter of fact, its only target is the FEMALE flea who lays eggs. When a female flea jumps on and bites a treated pet it ingests lufenuron. When the female lays eggs, the lufenuron is deposited in her eggs. Now here is the clincher. Sentinel states that lufenuron prevents "most" eggs from hatching or maturing into adults. Most? What about all the male fleas? Well logically, they and all the adult female fleas, remain on the animal. What?

Proheart6 and Proheart12: One of the worst is Proheart6 or Proheart12.  The active ingredient is moxidectin, delivered via injection; it’s said to protect against heartworms and hookworms for six/twelve months, but not whipworms or roundworms which are very common. First introduced in 2001, it was recalled in 2004 after over 5,500 adverse event reports, including about 500 deaths, but is now back on the market.  Because it lasts for SIX months or 12 months, if your dog has a reaction to it there is NO way to get it out of your dog’s body.  It’s there for 6 months or 12 months depending on which one you injected. 

Seresto Collar: There are also flea and tick collars like Seresto.  The active ingredients are imidacloprid (10%) and flumethrin (4.5%). Imidacloprid, which affects the central nervous system of fleas, is a member of the neonicotinoid class of insecticides; flumethrin, which repels and kills ticks, is in the pyrethroid class.  I took this next sentence right off the internet when the question was, “How many dogs have died from the Seresto collar?”  Answer: According to the documents submitted to the Midwest Center for Investigative Reporting, the EPA has received reports of at least 1,698 pet deaths related to the popular Seresto collars from 2012 to June 16, 2020. Overall, the agency took in more than 75,000 Seresto incident reports in that time frame.”   You can see more at this link: Popular Flea Collar linked to almost 1700 pet deaths.    Sadly, this product is the #1 seller of flea collars on Amazon.  


Many vets also like to use topical Heartworm and Flea preventatives like Revolution or Multi Advantage.  My vet uses multi-Advantage because he has seen breakthroughs with Revolution.  It appears to treat fleas, but some dogs still get heartworms.  I don’t like either product because I believe in the least amount of chemicals for your dog.  You don’t always have to treat fleas.  In the winter/colder months fleas are usually not a problem.  So why treat them for both?  

Why does my vet test for heartworms prior to refilling my heartworm preventative? 

Heartworm preventives do not kill adult heartworms.  Giving a heartworm preventive to a dog infected with adult heartworms may be harmful or deadly. If microfilariae are in the dog's bloodstream, the preventive may cause the microfilariae to suddenly die, triggering a shock-like reaction and possibly death.

Just to summarize, it voids my health guarantee if any of my owners use any of the following products: 

  1. Capstar

  2. Trifexis

  3. Comfortis

  4. Nexgard, 

  5. Nexgard Spectra, 

  6. Bravecto, 

  7. Simparica, 

  8. Simparica Trio, 

  9. Credelio

  10. Sentinel

  11. Proheart 6

  12. Proheart 12

  13. Seresto Collar 

I also do not recommend Revolution or Multi-Advantage topicals.

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