Fenbendazole (Panacur®, Safe-guard®) for Horses

Molly Price, DVM
By Molly Price, DVM on Mar. 22, 2024
woman standing with horse in ring

AzmanJaka/E+ via Getty Images

In This Article


What Is Fenbendazole for Horses?

Panacur® (active ingredient fenbendazole) is a veterinary deworming medication used in horses for the removal of worms including large and small strongyles, pinworms, and roundworms.

Panacur® is FDA-approved for use in veterinary medicine to treat a wide variety of worms in horses, cattle, swine and goats.

Panacur® is available over the counter as a dewormer paste or by prescription from your vet in liquid formulation. Containing the same active ingredient and concentration of fenbendazole as Panacur®, Safe-guard® is a similar over-the-counter dewormer available in a paste and medicated feed pellets.

In certain circumstances, your veterinarian may prescribe a compounded formulation of fenbendazole. Compounded medications are prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug, such as if your pet has trouble taking pills in capsule form, the dosage strength is not commercially available, or the pet is allergic to an ingredient in the FDA-approved medication. Compounded medications are not FDA-approved. They are created by either a veterinarian or a licensed pharmacist on an individual basis to best suit a patient’s particular needs. You can learn more about compounded medications here.

Panacur® and Safe-guard® have been evaluated for safety for horses of all ages, including foals and pregnant mares during all stages of gestation.

How Fenbendazole Works in Horses

Fenbendazole blocks the ability of worms to produce energy, which ultimately starves and kills the parasite. Immature life stages, such as larvae or eggs, may also be affected in some types of worms.

Fenbendazole Directions for Horses

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

Determine the proper dose according to your horse’s body weight.

Make sure your horse’s mouth is free of food, then administer this medication with an oral syringe onto the back of the tongue. The liquid formulation may also be administered by stomach tube.

Regular deworming at intervals of six to eight weeks may be required for horses due to the possibility of reinfection.

Missed a Dose?

Speak with your veterinarian about what to do if you forget to give a dose of fenbendazole. Generally, your vet may instruct you to give it when you remember, or if it is almost time for your horse’s next dose, to skip the missed dose and resume your normal dosing schedule. Do not give extra or double doses.

Possible Side Effects of Fenbendazole in Horses

When used as labeled, studies have shown that Panacur® and Safe-guard® tend to be well tolerated in horses without typically causing any side effects.

Higher dosages may potentially cause the dying parasites to release harmful substances (antigens), which can result in an allergic reaction (also known as hypersensitivity).   

Signs of hypersensitivity include red and itchy skin, hives, skin blisters, irritated eyes, watery nasal discharge, coughing or sneezing, trouble breathing, swelling of the nose, diarrhea, colic, behavior changes, and, in extreme cases, sudden death from shock.

Seek immediate medical treatment if you suspect your horse may be having an allergic reaction.

Human Side Effects

Fenbendazole is a veterinary medication not intended for use in humans. Wash your hands after handling this medication.

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.

If you accidentally ingest a veterinary 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)
  • Your horse’s condition worsens or does not improve with treatment
  • You see or suspect an overdose
  • You have additional questions or concerns about the use of fenbendazole, Panacur® or Safe-guard®

Fenbendazole Overdose Information for Horses

An overdose of fenbendazole in horses is unlikely to cause toxicity but can result in an allergic reaction (hypersensitivity) due to dying parasites releasing harmful substances (antigens).

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

Fenbendazole Storage for Horses

Always confirm storage requirements by reading the prescription label.

Compounded medications should be stored according to the compounding pharmacy’s label.

Store at or below 25 C (77 F). Protect from freezing.

Keep out of reach of children and pets.


What does Panacur® do for horses?

Panacur® and other fenbendazole products treat worms including large and small strongyles, pinworms, and roundworms in horses.

Is Panacur® a good horse dewormer?

Yes. Panacur® and other fenbendazole products are considered highly effective medications for removal of strongyles, pinworms, and roundworms, but it is important to understand that many species of small strongyles have developed resistance to fenbendazole deworming medications.

When the species causing the infection becomes resistant to a medication, the medication loses its ability to fully be effective at eradicating it. Talk to your veterinarian about the best deworming program for your horse that includes multiple dewormers from other drug classes to help prevent resistance.

Can I give Panacur® for horses to my dog?

No. It is important to only use horse medications in horses and dog medications in dogs. Horse medications are usually much more concentrated than dog medications, making overdoses in dogs more likely.

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.


Daniels S, Proudman C. Ovicidal efficacy of fenbendazole after treatment of horses naturally infected with cyathostomins. Veterinary Parasitology. 2016;227:151–156.

Zanet S, Battisti E, Labate F, Oberto F, Ferroglio E. Reduced efficacy of fenbendazole and pyrantel pamoate treatments against intestinal nematodes of stud and performance horses. Veterinary Sciences. 2021;8(3):42.


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