Dormosedan® Gel (detomidine hydrochloride) for Horses

Published May 23, 2024
white horse mouth being administered medication through application of the mouth.

Groomee/iStock / Getty Images Plus via Getty Images

In This Article


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 Dormosedan® Gel for Horses?

Dormosedan® Gel is an FDA-approved veterinary medication used for mild standing sedation and restraint in horses.

This equine medication can be prescribed by your veterinarian to help your horse feel calm and relaxed during horse care and husbandry procedures that may trigger anxiety, such as grooming, hoof care, “floating” or filing of the teeth, passage of a tube or scope, or taking X-rays.

Dormosedan® Gel is to be given at least 40 minutes prior to the procedure while the horse rests in a quiet place. In general, Dormosedan® Gel helps horses stay sedated and calm for approximately 90-180 minutes.

It is important to understand that it may take longer for the medication to take effect in horses that are already nervous, excited, or agitated. The medication may be less effective or may not work at all in severely agitated horses.

Dormosedan® Gel does not provide pain relief so it is not used for painful procedures.

Dormosedan® Gel Considerations

Dormosedan® Gel should not be used in horses with medical conditions such as abnormal heart rhythms (arrhythmias), heart failure, disorders of the blood vessels in the brain (cerebrovascular disease), breathing issues (respiratory disease), chronic kidney failure, shock, severe debilitation, or in horses with known hypersensitivity to it.

It also shouldn’t be used in horses already sedated or under anesthesia, or stressed due to fatigue, high altitude, or exposure to extreme temperatures (hot or cold).

It is important to note that Dormosedan® Gel has not been evaluated in horses younger than one year of age, ponies, or miniature horses.

Safety studies for Dormosedan® Gel have also not yet been performed in breeding, pregnant, or lactating horses at the time of this publication.

How Dormosedan® Gel Works in Horses

The active ingredient in Dormosedan® Gel is detomidine, which is classified as an alpha-2-adrenergic agonist.

Dormosedan® Gel causes sedation in horses 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, the horse feels calm. Dormosedan® Gel also causes muscle relaxation.

Dormosedan® Gel Directions for Horses

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

Dormosedan® Gel is placed under the tongue, where the medication will be absorbed into the body. Wear impermeable gloves when administering this gel to your horse. Make sure your horse’s mouth is free from food.

Do not give your horse food, treats, or water after administration, as this may water down the gel and diminish the amount that is absorbed. Dormosedan® Gel may not be effective if swallowed.

After administering the medication, allow your horse to rest in a quiet place for a minimum of 40 minutes.

Be careful when handling a sedated horse. Handling or sudden noises may cause a defense reaction (such as kicking) in a horse that appears to be heavily sedated.

Withhold food and water from your horse for up to three to four hours until your horse is fully recovered.

Missed a Dose?

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

Dormosedan® Gel Possible Side Effects

As Dormosedan® Gel takes effect, you may notice these reactions in your horse:

  • Sweating

  • Relaxed, distended penis (penile prolapse)

  • Lowering of the head, resulting in facial swelling especially around the eyes, drooling, and nasal discharge

  • Front legs planted in a firm stance

  • Slight swaying

  • Slight muscle tremors

  • Slow heart rate, sometimes abnormal heart rhythms (arrhythmias)

Human Side Effects

Dormosedan® Gel is not used in human medicine. Due to possible side effects, humans should never use medicine dispensed for their animals and animals should not be given any medicine dispensed for a human’s use.

Avoid handling and administering Dormosedan® if you have heart disease or high blood pressure, since accidental exposure can cause sedation, low blood pressure, and slow heart rate in people.

Impermeable disposable gloves should be worn when handling and administering Dormosedan® Gel, and when in contact with your horse's mouth after application.

Dormosedan® Gel 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 Dormosedan® Gel

Dormosedan® Gel Overdose Information for Horses

Signs of an overdose of Dormosedan® may include:

  • Sedation

  • Head droop

  • Swelling of the head

  • Discharge of the eyes and nose

  • Loss of balance

  • Sweating

  • Prolapsed penis

  • Slow heart rate

  • Slow breathing rate

  • Decreased gastrointestinal motility

  • Abnormal heart rhythms

If you suspect an overdose, immediately contact your veterinarian, seek emergency veterinary 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

Dormosedan® Gel Storage for Horses

Always confirm storage requirements by reading the prescription label.

Store at controlled room temperature 68–77 F.

Do not save any leftover medication in the syringes for reuse.

Any remaining medication should be disposed of in accordance with local requirements and federal prescription drug disposal guidelines, if applicable. Your veterinarian can offer more guidance on how to properly dispose of your medications.

Keep out of reach of children and pets.


What is Dormosedan® Gel used for in horses?

Dormosedan® Gel is used for mild standing sedation and restraint in horses to help them feel calm during horse care and husbandry procedures that may trigger anxiety.

How do you administer Dormosedan® Gel?

Dormosedan® Gel is administered to a horse under the tongue. This is where the medication is absorbed—it is not meant to be swallowed. Make sure there is no food in your horse’s mouth before administration.

How much Dormosedan® Gel do you give a horse?

The appropriate dose of Dormosedan® Gel from the dosing syringe is determined by the weight of your horse. Your veterinarian will tell you what amount of gel to give to your horse.

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.


Plumb DC. Detomidine. Plumb’s Veterinary Drugs. Updated July 2021. Accessed April 27, 2024.


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...

Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health