Why I Won’t Prescribe Sileo for Dogs With Noise Phobias

A faulty mechanism in Sileo’s syringe has caused a reported 80 cases of canine overdose.

Dexmedetomidine — Sileo is its brand name — has been around for decades. By: LauraTara

Sileo is a drug marketed for the last 2 years as a way to help dogs with noise phobias. When given by people at home, it’s dispensed as a gel into your dog’s cheek pouch with an oral syringe ring-stop mechanism that may be faulty, leading to overdoses.

The FDA issued a warning in 2017 after receiving 54 adverse drug reports involving Sileo overdoses. The pharmaceutical company, Zoetis, was asked to revise its labeling to better emphasize the need to secure the ring-stop mechanism to avoid accidental overdosing.

Although Zoetis has revised the labeling and provided enhanced training videos on its website to show how to administer Sileo, the FDA just released a second warning last week because now there are 26 additional reports of overdosing. As far as we know, no dogs have died from these overdoses.

As with any drug, the number of overdoses is probably underreported. Many people don’t report a drug reaction or overdose to the drug company — and some veterinarians don’t either.

Sileo Facts

Sileo isn’t new; its actual name is dexmedetomidine. It’s been around for decades and is used in anesthesia at veterinary hospitals, administered under the watchful eye of a veterinarian.

What’s new is that people now are able to administer it at home to their pets.

Sileo, as marketed, is an oral gel to be administered into the dog’s cheek pouch rather than the mouth. The administrator should wear gloves and should not be pregnant, and the drug should be given 30–60 minutes prior to the expected noise (i.e., fireworks or thunderstorms).

The syringe used to administer the oral gel to canines at home has some reported problems. This is why the FDA is now involved.

Lethargy and general sleepiness are 2 of many side effects of Sileo overdosing. By: manfredrichter

What Veterinarians Are Reporting

Opinions vary widely as to Sileo’s effectiveness for noise phobias. Noise phobias are a very difficult anxiety to treat. The labeling for Sileo claims it does not have to be part of a behavior modification program.

Vets dispensing Sileo have heard complaints about people not understanding how to use the oral syringe or being worried they gave “the whole syringe.”

The “overdose” is generally not life-threatening, but it looks scary, with side effects like:

  • Lethargy
  • Sedation
  • Sleepiness
  • Slow heart rate
  • Loss of consciousness
  • Shallow or slow breathing
  • Trouble breathing
  • Impaired balance or incoordination
  • Low blood pressure
  • Muscle tremors

There is a reversal, like an antidote, for this drug. Unfortunately, it is only available at a veterinary office — and you don’t want to be looking for an emergency hospital on the 4th of July.

Sileo Dosing

A study published in a British veterinary journal in April 2017 studied dogs affected by noise phobia related to the previous New Year’s Eve fireworks in Great Britain. They found the drug to be effective as long as it was given at “subsedative” doses. Sileo’s oral syringe and faulty ring-lock mechanism means you could give a sedative, not a subsedative dose.

Sileo is supposed to be given in the cheek pouch. If given into the dog’s mouth and down their throat, it is not absorbed well and therefore won’t help relieve the noise phobia. You are supposed to wait 2 hours before administering it again — this time, directly into the cheek pouch.

Veterinarians are largely concerned about where the onus lies when someone inadvertently overdoses the dog.

  • Did the veterinarian fail to instruct the person properly?
  • Did the person not watch the Zoetis video or were they still confused?
  • Was Mom, who watched the video, out at the time of the impending thunderstorm and instructed her teenage son at home to put the proper amount of medication into Alfie’s cheek pouch?
New veterinary drugs from profit-driven pharmaceutical companies may not always be safe for your pet. By: MichaelGaida

New Drugs May Come to Market Too Soon

I have always been wary of drug company claims and usually wait a year or 2 before prescribing a “new” drug. In this case, it may not be the drug so much as the flimsy dosing syringe.

Drug representatives from the veterinary pharmaceutical companies are sent out to detail new drugs to veterinarians. Big Pharma sends glossy brochures to veterinarians about their new and amazing drug that is the best thing to come down the pike since veterinarians learned to talk.

I don’t blindly trust the drug companies because most veterinary drugs hit the market without adequate testing. Sample size is often very small, and rigorous testing for safety may be limited due to corporate greed and the inability for government agencies to provide appropriate oversight.

Here’s a look at Sileo’s faulty syringe mechanism:

I try to look at independent research as much as possible. I don’t trust the initial literature provided by the drug company.

If a new drug might be critically important in saving pets’ lives, I ask the veterinary specialists to weigh in on the safety, efficacy and dispensing of the drug.

Until Zoetis fixes the dosing syringe, I’m going to wait before dispensing Sileo. If FDA and veterinary pressure prevails, the big pharmaceutical company should fix the problem they created in the first place.


This pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. It was last reviewed July 11, 2018.

Dr. Debora Lichtenberg, VMD

View posts by Dr. Debora Lichtenberg, VMD
Dr. Debora Lichtenberg, VMD, is a small animal and exotics veterinarian who has split her time between a veterinary practice in Pelham, Massachusetts, and her studio in New York City. Dr. Lichtenberg is a graduate of the University of Pennsylvania School of Veterinary Medicine with 30 years of experience. Her special interests are soft tissue surgery and oncology.

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