Fentanyl (Duragesic®, Sublimaze®) for Dogs and Cats


Overview of Fentanyl for Dogs and Cats

  • Fentanyl, also known as Duragesic® and Sublimaze®, is a very potent medication used to control pain for dogs and cats. Fentanyl also can cause sedation and depression of the central nervous system. Fentanyl is available as an injectable solution or as a transdermal (skin) patch. 
  • Fentanyl belongs to a general class of drugs known as opiates or narcotics. Other related drugs in this class include morphine, buprenorphine, meperidine and butorphanol.
  • As with all drugs in this class, fentanyl has high abuse and addictive potential and its use is regulated.
  • Fentanyl, and other drugs in this class, are controlled substances (Class ll) and can only be prescribed by a veterinarian with an active Drug Enforcement Agency license.
  • Fentanyl is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
  • Fentanyl by injection is approved for use in animals. The fentanyl skin patch is not approved for use in animals by the Food and Drug Administration but is prescribed legally by veterinarians as an extra-label drug.
  • Brand Names and Other Names of Fentanyl

  • This drug is registered for use in humans and animals.
  • Human formulations: Duragesic® (Janssen), Sublimaze®, Fentanyl Citrate and Droperidol® (Astra) and generics
  • Veterinary formulations: Innovar® – Vet (Mallinckrodt)
  • Uses of Fentanyl for Dogs and Cats

  • Fentanyl injectable is used to control pain, sedate and tranquilize.
  • Fentanyl patches are used for pain control.
  • Precautions and Side Effects

  • While generally safe and effective when prescribed by a veterinarian, fentanyl can cause side effects in some animals.
  • Fentanyl should not be used in animals with known hypersensitivity or allergy to the drug.
  • Other nervous system depressant drugs and sedatives must be used with caution when combined with fentanyl.
  • As with most opiates, this drug can cause breathing activity to diminish. This can be a problem, especially if there is lung disease already present.
  • Care must be taken when treating an animal with a fever. Increased body temperature can increase the amount of fentanyl absorbed and lead to overdosing.
  • Fentanyl may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with fentanyl. Such drugs include antihistamines, tranquilizers, barbiturates, other narcotics and monoamine oxidase inhibitors.
  • The pet must be prevented from eating a fentanyl patch. An overdose may result, leading to excessive sedation and depression.
  • A skin rash may develop at the site of the patch.
  • How Fentanyl Is Supplied

  • Fentanyl is available as a transdermal patch in 2.5 mg, 5 mg, 7.5 mg and 10 mg doses.
  • Fentanyl is also available in injectable form combined with another drug called droperidol. The ampules have 0.05 mg fentanyl and 2.5 mg droperidol per milliliter.
  • Dosing Information of Fentanyl for dogs and Cats

  • Medication should never be administered without first consulting your veterinarian.
  • Use of injectable fentanyl is confined to the hospital setting and subject to strict controls. Injectable fentanyl is not prescribed for home use. The dose used in cats and dogs can vary depending on the condition being treated. Sometimes a loading dose is given followed by a slow IV drip infusion (constant rate infusion [CRI]). A common strategy is to give 5 mcg per pound (10 mcg/kg) as a loading dose followed by 5 mcg per pound per hour (10 mcg/kg/hr) as a CRI. 
  • When used as a patch for pain relief, the effect of the drug may not occur until 12 to 24 hours after the initial administration. For this reason, alternative pain medications may be used along with the fentanyl patch in the early stages.
  • The dose of fentanyl is based on the weight of the animal.
  • Animals under 20 pounds (10 kg) receive a 2.5 mg patch.
  • For animals 20 to 40 pounds (10 to 20 kg), the 5 mg patch is recommended.
  • For animals 40 to 60 pounds (20 to 30 kg), the 7.5 mg patch is recommended.
  • For animals over 60 pounds (30 kg), the 10 mg patch is recommended.
  • For very small animals, 1/2 of the patch can be used. The patch should NEVER be cut. Placing tape to cover 1/2 of the patch is sufficient to reduce the dose.
  • The patch is only effective for three days and, if pain persists, the patch should be replaced by a veterinarian.
  • The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your pet feels better, the entire treatment plan should be completed to prevent relapse or prevent the development of resistance.
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    Analgesic Drugs



    Gastroenterology & Digestive diseases
    Orthopedics & Musculo-Skeletal diseases
    Multiple organ systems can be affected


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