Derm Spotlight: Let’s Stop Calling Flea Prevention Poison

Lack of Flea Prevention Causes Issues

A common refrain we hear from pet owners is, “I don’t give that poison to my pet!” These owners mean well, and they’re trying to do what’s best for their beloved pets, but calling flea prevention “poison” is not accurate. A lack of good flea prevention is very likely contributing to a pet’s skin problems. Let’s unpack this controversial topic.

Vague FDA Statements

On September 20, 2018, the FDA released a public health advisory warning owners of the potential for neurologic adverse events in dogs and cats when treated with drugs that are in the isoxazoline class. The isoxazoline class includes a number of the newer flea and tick preventions such as Bravecto (fluralaner), Nexgard (afoxalaner), Simparica (sarolaner), Credelio (lotilaner), and Revolution Plus (selamectin and sarolaner). Within hours of the FDA’s statement, the Internet exploded with talk about the possible side effects. Social media posts went viral. Petitions circulated demanding these drugs be removed from the market. Dog breeders made potential buyers promise never to use these products. You know how hysteria can spread online.

The problem with the FDA warning is that it made no mention of how uncommon these side effects are, nor did they explain what level of concern they were. They did say, “The FDA considers products in the isoxazoline class to be safe and effective for dogs and cats,” but that sentence was overshadowed by mentions of “muscle tremors, ataxia, and seizures in some dogs and cats.” Seizures? That sounds super scary! Why would anyone give their pet something that could possibly kill them?! Panic spread in the aftermath of such as vague and uninformative press release.

Luckily, the European counterpart of the FDA (The European Medicines Agency) was much more informative: “Side effects with Simparica are not common. However, the following side effects are seen in less than 1 dog in 10,000: mild and short-lived vomiting and diarrhea as well as tremor (shaking), ataxia (inability to coordinate body movements) or convulsions. These signs usually resolve without treatment.”

Facts on Side Effects

So how common are these neurological side effects? Less than 1 in 10,000 is quite rare! How dangerous are these side effects? Most resolved without treatment. Yes, even a seizure, which appears very frightening to the average person, usually stops on its own after a few minutes. Stopping the drug in the vast majority of cases leads to stoppage of symptoms and no further side effects. If your pet already has a neurological issue, talk about it with your veterinarian before using one of these drugs. For all other pets, the chance of this causing a life-threatening issue is really, really low. The FDA requires that any serious side effect that occurs within 15 days of administering a drug be reported. Fifteen days is a long time. Most pets that die suddenly had a serious underlying problem like a tumor that suddenly ruptured. Flea prevention gets blamed because grieving pet owners need to find some reason for the death, and for many pets, flea and heartworm prevention were the only drug they were given in last month. That doesn’t mean the drug is what caused the death.

The Real Truth

You might ask, why harp on this issue? What kick-back does BigPharma offer for us to say these things? The honest answer is: flea prevention is not a revenue-generating product. We advise on flea prevention because we care about our patients and want their skin disease to resolve. Most of patients we see as veterinary dermatologists have skin allergies. Most pets with skin allergies are also allergic to flea saliva. When they get bit by a flea, a protein in the flea saliva starts an immune reaction that leads to inflammation in the skin. This shows up as itching, redness, hair loss, and skin infections. We have seen countless patients that would not get better, no matter what was tried, until their owner used good flea prevention. Even when the owner insisted they had never seen a flea on their pet, it doesn’t matter!

Occasional flea bites are enough to contribute to skin inflammation, and fleas are tiny and well hidden by pet fur. If your pet goes outside, they are exposed to fleas. Even if you spray the yard, even if you live in a well-maintained community, even in the winter here in Texas, flea exposure is eminent. Older topical products like Frontline, Advantage, Advantix don’t seem to work as well as they used to. We see fleas living happily on patients using these products, Sentinel doesn’t kill fleas, it only prevents reproduction. Even Comfortis and Trifexis don’t seem to work as well as in the past. The isoxazolines are the most effective flea prevention drugs on the market right now.

We are not saying this to make money. We tell clients that they can buy it from ADRC for convenience or they can get it from their regular vet clinic, or even order it online as long as it’s a reputable pharmacy (do watch out for counterfeit meds). According to our practice financial records, Simparica accounts for only 2.2% of all sales—this is not a revenue-producing product. We see patients every single day who don’t get better until they’re on good flea prevention. We will say again for the people in the back: If your pet has skin disease, YOUR PET NEEDS A GOOD FLEA PREVENTION TO GET BETTER. If your pet doesn’t have skin disease, there are still a number of flea and tick-borne diseases that can be life-threatening. We would never give your pet poison. Please don’t believe everything you read on the Internet. Flea prevention is not poison.