Sileo® (Dexmedetomidine Oromucosal) Gel for Dogs

Published Nov. 13, 2023
little dog hiding under furniture

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PetMD’s medications content was written and reviewed by veterinary professionals to answer your most common questions about how medications function, their side effects, and what species they are prescribed for. This content shouldn’t take the place of advice by your vet.

What Is Sileo® for Dogs?

Sileo® (dexmedetomidine oromucosal gel) is the first and only FDA-approved medication for the treatment of fear and anxiety triggered by loud noises (noise aversion) in dogs.

Sileo® can be prescribed by your veterinarian to help your dog feel calm when exposed to loud noises such as fireworks, construction work, vacuum cleaners, thunderstorms, and any other loud environment that may trigger anxiety.

Sileo® must be given 30-60 minutes before the anxiety-triggering noise event or at least immediately after the dog starts to show signs of fear and anxiety in order to be effective.

Sileo® Considerations

Only dogs that pass a clean bill of health from their veterinarian should be prescribed Sileo®.

Sileo® should not be used in pets with certain medical conditions such as heart disease, respiratory disorders, shock, liver disease, kidney disease, or severe debilitation.

It also shouldn’t be prescribed for pets who are stressed due to fatigue, exposures to extreme weather (hot or cold), or in pets who are hypersensitive to it.

Giving Sileo® with certain medications can result in health risks to your pet, so it is important to discuss your pet’s medications and medical conditions with your veterinarian first.

It is important to note that Sileo® has not been evaluated in dogs younger than 16 weeks of age or in dogs with dental or gum disease that could affect the absorption of Sileo®. Since studies to determine its level of safety in breeding, pregnant, or lactating dogs are lacking, Sileo® is not currently recommended for use in these pets to treat noise aversion behaviors.

How Sileo® Works

The active ingredient in Sileo® is dexmedetomidine, which is classified as an alpha-2-adrenergic agonist.

Sileo® decreases fear and anxiety in pets by binding to alpha-2-adrenergic receptors in the brain. This prevents norepinephrine (NE), a specific “fight-or-flight" chemical messenger involved in the body’s response to stress, from being released. When NE levels are lowered in the brain, your pet will exhibit fewer of the physical and behavioral signs associated with anxiety and fear.

Sileo® Directions

Follow the directions on the drug label or as provided by your veterinarian.

Sileo® is an oramucosal gel, which means that it is a gel that is placed inside the mouth between your dog’s cheek and gums, where the medication will be absorbed into the body. Wear gloves when administering this gel to your dog.

Do not give your dog food, treats, or water after administration, as this may water down the gel and diminish the amount of Sileo® in between the cheek and gums where it is absorbed.

Sileo® may not be effective if swallowed. If Sileo® is swallowed, do not repeat the dose for at least two hours to avoid overdose in case some of the medication was already absorbed through the gums and cheek.

When dialing the appropriate dose on the syringe, the ring-stop must be locked in place prior to administration. If the ring-stop is not fully locked before dosing, an accidental overdose may occur.

Do not give Sileo® to a dog who is still sleepy or sedated from a previous dose.

Keep your dog warm and comfortable, and do not offer food or water until Sileo®'s effects have worn off within a few hours.

If your dog is still showing signs of fear or anxiety after Sileo® administration, check with your veterinarian first before giving Sileo® more than once to your dog.

Do not use Sileo® in pregnant, breeding, or lactating dogs, in puppies, or in dogs of advanced age, as safety studies have not been performed in these groups.

Missed a Dose?

Since Sileo® is given as needed and not routinely, always make sure you understand when you can and cannot administer the medication to your dog. If you’re unsure, contact your veterinarian.

Sileo® Possible Side Effects

Sileo® is typically well-tolerated in most dogs.

Possible side effects include:

  • Pale gums where Sileo® was applied (a transient effect)

  • Drowsiness

  • Weakness

  • Vomiting

  • Loss of balance

  • Muscle tremors

  • Inappropriate urination

Human Side Effects

The active ingredient in Sileo®, dexmedetomidine, is also a prescription medication for humans, frequently with dosages different from those prescribed for your pet by a veterinarian. Due to possible side effects, humans should never use medicine dispensed for their pets and pets should not be given any medicine dispensed for a human’s use.

Avoid handling and administering Sileo® if you are pregnant, since it can be absorbed through the skin and may induce uterine contractions and/or decrease your baby’s blood pressure. Impermeable disposable gloves should be worn when handling and using filled syringes, administering Sileo®, and during any contact with your dog's mouth after application.

Sileo® can be absorbed through your skin, mucous membranes (mouth, gums), and eyes. If you are accidentally exposed to this medication or ingest this medication, call your physician or the national Poison Control Center hotline at 800-222-1222.

Call Your Vet If:

  • Severe side effects are seen (see above)

  • You see or suspect an overdose

  • You have additional questions or concerns about the use of Sileo®

Sileo® Overdose Information

Signs of an overdose of Sileo® may include sedation, inappropriate urination, vomiting, loss of balance, weakness, and fainting due to abnormally slow heart rate (bradycardia).

If you suspect an overdose, immediately contact your veterinarian, seek emergency medical care, or call an animal poison control center. Consultation fees often apply.

Pet Poison Helpline (855) 764-7661

ASPCA Animal Poison Control (888) 426-4435

Sileo® Storage

Always confirm storage requirements by reading the prescription label.

Sileo® oromucosal gel syringes (unopened or opened) should be stored in the original package at controlled room temperatures from 68 to 77 F. Brief exposure to temperatures of 59 to 86 F are permitted.

Recap opened syringes and return them to the original package to protect the content from light and moisture. Make sure that the package is closed properly. Use or discard syringe contents within four weeks after opening the syringe.

Keep out of reach of children and pets.

Sileo® for Dogs FAQs

How do you administer Sileo® in dogs?

Sileo® gel is applied in the inner lining of the mouth between your dog’s cheek and gums (transmucosally) with a syringe. This is where the medication is absorbed—it is not meant to be swallowed.

How much does Sileo® for dogs cost?

The cost for Sileo® mostly depends on your dog’s weight and can vary slightly depending on the individual prices of your veterinary hospital or pharmacy.

Does Sileo® make dogs sleepy?

Sileo® is formulated to provide a low dose of dexmedetomidine to help your dog remain calm (but not sleepy) and exhibit less trembling, hiding, and panting when exposed to loud or noisy environments.

How quickly does Sileo® work in dogs?

Sileo® typically starts working about 30 minutes after administration.

No vet writer or qualified reviewer has received any compensation from the manufacturer of the medication as part of creating this article. All content contained in this article is sourced from public sources or the manufacturer.

Featured Image: Capuski/iStock via Getty Images Plus

Molly Price, DVM


Molly Price, DVM


Dr. Molly Price has practiced small animal medicine for over 20 years and is a graduate of Texas A&M College of Veterinary Medicine. She...

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