Are the combination chewable heartworm/flea/tick medications safe for my dog?
In the last couple of years, pharmaceutical companies have developed and manufactured new chewable combination pills – heartworm prevention that also protects against fleas. Some newer products even kill ticks. But at what expense to our pets and our environment? If the medication is chewable, that means it somehow needs to get to the surface to protect from fleas and ticks, while the chemical also needs to float through the blood to kill any baby heartworms in the blood stream. Follow the hyperlink for a refresher on how heartworm infection works.
Monthly topical products used to be the “norm” for flea and tick prevention, while a monthly chewable tablet prevented heartworm infection. Because topical products make the fur greasy, can cause the pet to scratch out the fur, and can smell bad, some owners express dissatisfaction with topical products. Thus explaining the logic behind the development of chewable products. Pet owners like the convenience of a chewable product, more so when it’s an “all-in-one” pill.” However, where topical products can be washed off should there be a reaction, chewable tablets (obviously) cannot. This means if your dog has a reaction to the chewable tablet, there is little that can be done other than treat symptoms.
The following is a brief introduction to the new products and their potential side effects:
Trifexis® has been on the US market since 2011. Some dogs vomit from the medication, even when it is given as directed with a meal. Some dogs develop fatal kidney failure and ultimately die from the use of Trifexis®.
Nexgard® has been available since 2013. Like Trifexis®, side effects can include vomiting and diarrhea. Other side effects are itching and seizures.
Bravecto® has been in manufacture in the US since 2014. It is also linked to seizures; some dogs’ seizures are untreatable and they either die or are euthanized.
Simparica® is brand new, just approved in 2016. In spite of several dogs in the basic studies having seizures and one dog had to be euthanized, this product will soon be sold in veterinary clinics all across America.
Because the active ingredient of these new insecticides (the chemical class is Isoxazoline) are inside your dog’s body, a flea or tick must bite your dog in order 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! Yuck.
Safety testing procedures were not sufficient for these chemicals. The makers of Bravecto® published a “safety study” in which 32 dogs were evaluated for safety of the product. Sadly, if this had been a human-tested product, a minimum of 60 patients would have been tested to accurately detect side effects. This means a minimum of 60 test subjects are needed to detect side effects; 32 test subjects allows for an excellent opportunity to miss detecting an adverse events (like seizures and death). Apparently, pet products do not undergo the same scrutiny during testing as human products, even though the majority of pet owners feel their pets are part of the family!
Perhaps the pharmaceutical industry sees this as a win-win: if the dog does well on these products, more product is sold. If the dog becomes ill on these products, the veterinarian and the drug company sell even more product while attempting to save the affected dog’s life. For them, it’s a win-win. For the pet owner and the pet – it’s a game of Russian Roulette, a no-win situation.
Given that introduction – do you feel safe giving these new chemicals to your pet?
Dr. Cathy Alinovi DVM
As a practicing veterinarian, Dr. Cathy treated 80% of what walked in the door — not with expensive prescriptions — but with adequate nutrition. Now retired from private practice, her commitment to pets hasn’t waned and she looks forward to impacting many more pet parents through her books, research, speaking and consulting work. Learn more at drcathyvet.com