Morphine for Dogs and Cats

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morphine for dogs and cats


Overview of Morphine for Dogs and Cats

  • Morphine Sulfate, commonly known just as “morphine”, is a well-known drug sometimes used for dogs and cats to alleviate pain. It is derived from the opium plant, which contains a naturally occurring substance found to relieve pain.
  • The body contains various opiate receptors involved in pain detection and regulation. Morphine acts on certain receptors, primarily mu receptors, resulting in analgesia (pain relief).
  • Morphine affects various body functions. Dogs and cats may vomit after administration. Dogs usually defecate immediately following injection. Panting may also occur.
  • If necessary, the effects of the drug can be reversed with administration of naloxone.
  • Morphine should be used with extreme caution in cats. The enzyme that helps metabolize morphine is deficient in cats, which results in potential brain and spinal cord stimulation.
  • All morphine products are prescription and class II controlled substances. Its use is stringently regulated by the Drug Enforcement Agency.
  • Morphine is a prescription drug and can only be obtained from a veterinarian or by prescription from a veterinarian.
  • This drug is not approved for use in animals by the Food and Drug Administration but it is prescribed legally by veterinarians as an extra-label drug.

Brand Names and Other Names of Morphine

  • This drug is registered for use in humans only.
  • Human formulations: Infumorph (Elkins-Sinn) and Astramorph PF (Astra)
  • Veterinary formulations: None
  • Morphine is supplied by numerous drug companies with a variety of trade names and various generic formulations.

Uses of Morphine for Dogs and Cats

  • The most common use of morphine is to treat pain in dogs and cats.
  • It is also used to reduce coughing and to reduce diarrhea in dogs.
  • For some animals, morphine can help alleviate anxiety and can help sedate before anesthesia.

Precautions and Side Effects

  • While generally safe and effective when prescribed by a veterinarian, morphine can cause side effects in some animals.
  • Morphine should not be used in animals with known hypersensitivity or allergy to the drug.
  • Morphine should be avoided in animals with liver disease, kidney disease, underactive thyroid gland, hyperactivity or Addison’s disease.
  • In very young, older and severely debilitated animals, morphine should be used with caution.
  • Morphine should be used with extreme caution in animals with head trauma, acute abdominal conditions and lung disease.
  • Avoid morphine in animals with diarrhea associated with toxin ingestion.
  • Animals stung by scorpions should not receive morphine. It has been shown to increase the potency of the venom.
  • Morphine may interact with other medications. Consult with your veterinarian to determine if other drugs your pet is receiving could interact with morphine. Such drugs include antihistamines, anesthetics, tranquilizers and monamine oxidase inhibitors (Prozac-like drugs).
  • Adverse effects associated with morphine include nausea, vomiting, slowed intestinal movement, constipation, restlessness, low blood pressure, slowed heart rate, slowed breathing, behavior changes and seizures.
  • The most profound adverse effects associated with morphine are suppression of breathing and sedation.
  • The use of morphine in cats is controversial. It can be associated with increased body temperature and nervous system excitement.
  • Chronic administration can lead to physical dependence.

How Morphine is Supplied

  • Morphine is available in injectable form in a variety of concentrations and bottle size.
  • Morphine tablets are available in 10 mg, 15 mg, 30 mg, 60 mg, 100 mg and 200 mg sizes.
  • Morphine is also available in an oral solution in various concentrations.
  • Morphine is also available in rectal suppositories in 5 mg, 10 mg, 20 mg or 30 mg sizes in 12 and 50 suppository containers.

Dosing Information of Morphine for Dogs and Cats

  • Medication should never be administered without first consulting your veterinarian.
  • Dogs are dosed at 0.05 to 0.12 mg per pound (0.1 to 0.25 mg/kg) intramuscular or subcutaneous every 3 to 4 hours or as needed. The oral dose of morphine in dogs is 0.7 to 1.5 mg per pound (1.5 to 3 mg/kg) every 12 hours.
  • Morphine administration is controversial in cats. It is usually administered in combination with a tranquilizer. The dose of morphine is 0.02 to 0.1 mg per pound (0.05 to 0.2 mg/kg) intramuscular or subcutaneous as needed.
  • 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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