Morphine
Also known as: Astramorph PF, Avinza, DepoDur, Infumorph, Kadian, MSIR, MS Contin, Oramorph SR, RMS, Roxanol, Morphine
Morphine is a potent, highly regulated pain-relieving medication typically administered in a hospital setting under direct veterinary supervision. * **What to Expect:** Your pet may appear sedated, sleepy, or unusually quiet. Dogs often pant heavily and may vomit or defecate shortly after receiving the drug. * **Cats and Horses:** May sometimes appear restless, pace, or have wide-open eyes instead of appearing sleepy. This is a known species difference. * **At-Home Care:** If your pet is sent home with oral morphine, keep it strictly out of reach of children and other animals. It is a highly controlled substance (Schedule II). Do not adjust the dose without consulting your veterinarian.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
- As an analgesic
- As an analgesic
- For post-op pain
- For analgesia
- For analgesia
- For analgesia
- Epidural administration for pain control
- As a preanesthetic in critical patients
- For adjunctive treatment of cardiogenic pulmonary edema
- For analgesia
- For epidural (Adult horses)
- For epidural (Foals)
- For analgesia
- Epidural analgesia
How it is given
Possible side effects
- Histamine release (hypotension, vasodilation)
- Respiratory depression
- Bronchoconstriction
- CNS depression (dogs, primates) or excitation (cats, horses, ruminants)
- Physical dependence (with chronic use)
- Hyperthermia (cattle, goats, horses, cats)
- Hypothermia (dogs, rabbits)
- Nausea and vomiting
- Decreased intestinal peristalsis and constipation
- Initial defecation (dogs)
- Panting (dogs)
- Bradycardia or tachycardia
- Histamine release (if given rapidly IV)
Cautions & contraindications
- Hypersensitivity to narcotic analgesics
- Patients receiving monoamine oxidase inhibitors (MAOIs)
- Diarrhea caused by a toxic ingestion (until toxin is eliminated)
- Scorpion envenomation (Centruroides spp. - potentiates venom)
- Conditions where vomiting is contraindicated (e.g., raised intraocular pressure)
- **Extreme Caution:** Patients with head injuries, increased intracranial pressure, acute abdominal conditions (e.g., colic - may mask clinical signs), and respiratory disease or acute respiratory dysfunction. **Caution:** Hypothyroidism, severe renal insufficiency (acute uremia), adrenocortical insufficiency (Addison's), and geriatric or severely debilitated patients. > **Important Notes:** > * **IV Administration:** Must be given slowly to avoid significant hypotension and histamine release. > * **Envenomation:** Avoid in envenomation situations, as clinical signs associated with histamine-release can be confused with anaphylaxis. > * **Uremia:** Because of its effects on vasopressin (ADH), urine flow can decrease by up to 90% in dogs given large doses.
Drug interactions
- CNS Depressants (anesthetics, antihistamines, phenothiazines, barbiturates): May cause increased CNS or respiratory depression when used with morphine.
- Diuretics: Opiates may decrease diuretic efficacy in congestive heart failure patients.
- Monoamine Oxidase Inhibitors (MAOIs, e.g., amitraz, selegiline): Use with extreme caution; contraindicated in humans due to risk of severe opiate overdose signs.
- Skeletal Muscle Relaxants: Morphine may enhance neuromuscular blockade.
- Tricyclic Antidepressants (clomipramine, amitriptyline): Morphine may exacerbate the effects of tricyclic antidepressants.
- Warfarin: Opiates may potentiate anticoagulant activity.
- CNS depressants (anaesthetics, antihistamines, barbiturates, phenothiazines, tranquillizers): Increased CNS or respiratory depression
Frequently asked questions
What is Morphine used for in pets?
Morphine is a potent, highly regulated pain-relieving medication typically administered in a hospital setting under direct veterinary supervision. * **What to Expect:** Your pet may appear sedated, sleepy, or unusually quiet. Dogs often pant heavily and may vomit or defecate shortly after receiving the drug. * **Cats and Horses:** May sometimes appear restless, pace, or have wide-open eyes instead of appearing sleepy. This is a known species difference. * **At-Home Care:** If your pet is sent home with oral morphine, keep it strictly out of reach of children and other animals. It is a highly controlled substance (Schedule II). Do not adjust the dose without consulting your veterinarian.
Is Morphine safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
Worried about your pet?
Peqaboo’s AI helps you track symptoms, understand lab reports, and know when to see a vet.
Get the Peqaboo app