405 Heron Drive Suite 200
Swedesboro, NJ 08085
Ph 800.331.8272

Morphine Sulfate for Veterinary Use

By Evan Ware, DVM

Basic Information

Morphine sulfate is a narcotic pain reliever derived from the opiate plant. It can be used in veterinary medicine to alleviate moderate to severe pain. In some cases, it can be used to help diminish coughing and to decrease diarrhea in dogs.

How Morphine Sulfate Alleviates Pain

Opiate receptors that regulate and detect pain are throughout the body. Morphine sulfate effectively inhibits these receptors, primarily mu receptors, resulting in pain alleviation.

Since morphine sulfate affects many biological functions, many dogs and cats can vomit or defecate immediately after morphine sulfate is injected. Some dogs can start panting excessively after administration as well.

Possible Side-Effects of Morphine Sulfate

Morphine sulfate is a very powerful analgesic, so there is always a possibility that side effects can arise when taking this medication. The most-common side effects are nausea, vomiting, constipation, restlessness, behavioral changes, reduced blood pressure and heart rate, slowed breathing, and seizures.

Use of morphine sulfate in cats is not as common as it is in dogs, as cats can experience elevated body temperature and nervous system excitement.

Morphine Sulfate Drug Interactions

Morphine sulfate potentially can interfere with or enhance other medications the patient may be on, including monoamine oxidase inhibitors, tranquilizers, anesthetics, and antihistamines. To eliminate or reduce the risk of a drug interaction, the veterinarian should know the animal's drug regimen.

Morphine Sulfate Precautions

Morphine sulfate should be avoided if the patient has had a previous allergic reaction to it. It also should be avoided in patients with pre-existing liver or kidney disease, Addison's Disease, an underactive thyroid gland, hyperactivity, and in cases involving diarrhea because of toxin ingestion.

Morphine sulfate should not be administered to a dog that has been stung by a scorpion, as the drug can increase the potency of the venom.

This drug should be used with extreme caution in older animals, severely debilitated animals, and those with serious head trauma, lung disease, and acute abdominal conditions.

For Veterinary Practices
Prescribe Now
For Pet & Horse Owners
Manage Your Prescriptions


Therapeutic Class
Opiate Agonist

Dogs, Cats, and Horses

May Be Prescribed by Vets for:
Acute Pain

Search for Available Dosage Forms

About the Author

Dr. Evan Ware

Evan Ware, DVM

Dr. Evan Ware is a veterinary practitioner in Phoenix, Arizona. He received both his undergraduate degree in microbiology and his Doctorate of Veterinary Medicine from The Ohio State University.

Dr. Ware is currently the Medical Director of University Animal Hospital (VCA) and is also the owner of two other hospitals, including Laveen Veterinary Center and Phoenix Veterinary Center. His areas of interest include orthopedic medicine and surgery, veterinary oncology and chemotherapy, and general and advanced soft-tissue surgery.

Tags: How Does Morphine Sulfate Alleviate Pain, Morphine Sulfate, Morphine Sulfate Drug Interactions, Morphine Sulfate Precautions, Possible Side Effects of Morphine Sulfate