A black cat crossing your path signifies that the animal is going somewhere - Groucho Marx
Fleas and ticks can get on your pet's nerves. But apparently so might some medications to get rid of these pests.
The U.S. Food and Drug Administration (FDA) has issued a warning that medications in the isoxazoline class such as Bravecto, Credelio, Nexgard and Simparica may do more than just combat flea or tick infestations. These medications have the potential of causing seizures, ataxia, muscle tremors, or other neurological problems in your pets. Ataxia is a condition in which your pets can't control their muscle movements and thus may have trouble walking, balancing, or speaking. Of course, you may not necessarily be able to tell if your pet is having difficulty speaking. But the FDA warning means that you should be on the lookout for any struggles that your pet may be having after taking these medications.
It is not a complete surprise that these medications may affect your pet's nervous system. After, these medications act by messing with the nervous systems of fleas and ticks. Your pet, typically a dog or cat since alpacas are not common household pets, will first munch on the medication. The medication then gets into your pet's bloodstream. There the medication may enter any flea or tick that is actively feeding on your pet's blood.
That's where the fun begins for the fleas and ticks. As with humans, nerves in fleas and ticks acts like wires conducting electrical signals that control movement and other functions. These electric signals normally jump from nerve to nerve via neurotransmitters such as gamma-aminobutyric acid (GABA) and glutamate. However, the medication can interfere with the actions of these neurotransmitters, impeding the transmission of these electrical signals. This can then paralyze and kill the fleas and ticks, in essence short-circuiting their nervous systems. Dead fleas and ticks also can't lay eggs and reproduce.
With this mechanism of action, it shouldn't be a complete surprise that the medications may also screw with your pet's nervous system. But before you freak out about the medication paralyzing and killing your pets, keep in mind that the medications are still FDA-approved for use in pets, assuming that your pet is not a giant flea. Fleas and ticks are thankfully much smaller than dogs and cats. So they tend to be more susceptible to smaller amounts of the medications. They also have different anatomy and physiology.
Note that the FDA didn't say how common such side effects in dogs and cats may be. The FDA only issued a warning and asked manufacturers to include the warning on their labels. Currently, the risk nay not be high since the FDA did not advise against using the medications for your dogs and cats.
So, for you fleas and ticks out there hoping that the FDA would pull these medications from the market, sorry that's not going to happen. If you are a human, this news may not change your flea and tick control methods but don't use these medications on your pet without guidance from a veterinarian. Keep your veterinarian informed about any changes in your dog's or cat's behavior while on these medications. If you are a veterinarian, make sure that pet owners are aware of these potential side effects and discuss flea and tick control options if they are concerned. And if you are a dog or cat, woof, woof, woof, and meow, meow, meow.
Source: Bruce Y Lee, Pets, If You Are On These Flea And Tick Medications, Beware Of Seizures, Forbes, September 22, 2018.