The U.S. Food and Drug Administration is alerting dog owners and veterinarians about the risk of accidental overdose to dogs treated with the drug Sileo, according to a statement released today by the FDA Center for Veterinary Medicine. Sileo, a prescription gel manufactured by Zoetis given to dogs by mouth to treat noise aversion, is packaged in an oral dosing syringe with a ring-stop mechanism that must be “dialed” and locked into place in order to set the correct dose for the dog. Overdose can occur if the ring-stop is not fully locked. Sileo hit the market in May 2016; to date, the FDA stated it has received 28 reports involving Sileo overdoses in dogs due to the ring-stop mechanism not properly locking at the intended dose. Fifteen of the 28 reports state that dogs experienced clinical signs of overdose, including lethargy, sedation, sleepiness, slow heart rate, loss of consciousness, shallow or slow breathing, trouble breathing, impaired balance or incoordination, low blood pressure and muscle tremors. No deaths have been reported. The FDA stated it has not determined at this time whether the reported overdoses were due to improper use of the ring-stop. The FDA strongly encourages veterinary staffs to provide education in proper operation of the syringe to dog owners before dispensing the drug and of potential signs of overdose. Zoetis also has provided online resources, which demonstrate the proper operation of the syringe and administration technique in detail for veterinarians and for dog owners. In response to the FDA's warning, Zoetis offered the following statement: “Sileo comes in the form of a gel, which the pet owner administers between a dog’s cheek and gum using a specially designed syringe. The syringe's lock mechanism allows the pet owner to administer the correct dose to their dog. There have been rare reports of overdose due to improper administration (failure to securely lock the ring-stop) by the pet owner. In those cases, clinical effects were temporary. We at Zoetis take these reports seriously. The health and well-being of animals is our highest priority. “As with any prescription medication, it is important for pet owners to fully review the instructions to ensure proper administration to a pet. So that dogs fully benefit from Sileo, we encourage veterinarians to discuss with pet owners how to use the syringe and administer Sileo. We also encourage pet owners to review the step-by-step dosing instructions that are included in the Sileo package and the instructional videos available online on the Sileo product website.”
