On Thursday, September 20, 2018, the U.S. Food and Drug Administration (FDA) issued an alert concerning Isoxazoline flea and tick preventatives. These products include Nexgard, Bravecto, Simparica and Credelio. The alert is for potential neurologic side effects of these products.
The information that the FDA is providing is not necessarily new. Before releasing a pharmaceutical product to become available for animal use, rigorous safety studies must be completed to receive FDA approval. During the process of testing these flea and tick medications, rarely, neurologic side effects were noted, including muscle tremors, stumbling, and seizures. After 3 ½ years of prescribing these products we have had one patient experience seizures shortly after administration of an isoxazoline product and alerted the manufacturer. The patient has had no further seizures or other side effects since discontinuing the product. However, other rare side effects such as brief nausea or diarrhea were reported more often. These products are labeled as prescription and we require a physical examination of your pet prior to sending home the first dose due to these types of reasons.
After a medication is released by the FDA to be freely prescribed to the general population, the FDA continues to monitor the medication’s effectiveness and safety. This is general rule for all pharmaceuticals, and we think this is an important one. Once a pharmaceutical enters the general population, it is used by thousands and potentially millions more pet patients than could ever be tested through clinical trials. With the higher numbers of product use, sometimes side effects that were not known previously become evident. At that time, the FDA may elect to submit alerts to veterinarians and the general population, change the labeling of a product, or completely remove it from distribution.
Flea and tick concerns:
Veterinarians do know that diseases caused by fleas are exceptionally common in the South Carolina lowcountry. Fleas cause significant pathology/discomfort for our pets, can spread diseases to people and when severe, can be life threatening. It is not uncommon for our practice to see multiple appointments with our patients each day that involve skin infections and discomfort secondary to flea bites and flea infestations. We often use antibiotics and anti-inflammatory products to treat these conditions. Those products unfortunately can also have adverse side effects for the patient.
The Companion Animal Parasite Council (CAPC) is formed of a group of veterinarians dedicated to tracking the prevalence of parasites affecting our pets. CAPC has reported annual increases in tick borne diseases (including Lyme disease) and continue to recommend year-round flea and tick preventatives for all at risk dogs and cats. At Charleston Harbor Vets we have begun to test for tick borne diseases annually and have found that many dogs have been exposed to diseases such as Lyme disease indicating that our local population is at risk.
Unfortunately we do not have a proven safe and 100% effective product for our pets to prevent flea and tick infestations. However we have found that neurologic side effects are much lower when using these products than the risk of disease if we chose not to use them. Currently, our team continues to recommend Nexgard and uses it consistently for prevention for our own dogs. However, if you have any questions or concerns please call, email, or make an appointment to meet with a doctor. We can discuss the risks and benefits and help you find the right products for you and your pet.
-Dr. Blackwood and Dr. Kahuda