Morphine Side Effects on Dogs

By Mary Lougee

The most notable side effect on dogs while taking morphine is marked drowsiness that causes more sleep than usual as the pain relief medication works. This side effect usually wears off as your pooch gets used to the medication. Severe side effects, such as diarrhea, vomiting, labored breathing and sleeping constantly, require a veterinary visit because some pets are hypersensitive to morphine.

Morphine Basics

Morphine is an opioid, or narcotic, pain medication. It is prescribed for moderate to severe pain after surgery, advanced cancer pain and severe arthritis.

Morphine is available in tablets, extended-release tablets and an oral suspension for home usage. The extended-release tablets serve to mitigate severe pain in dogs with cancer. A veterinarian can administers an injectable form.

Common Side Effects

The most common side effect of morphine in dogs is drowsiness and sedation. Your dog may suddenly defecate after his first dose of morphine. It's best to keep him in an area that is easy to clean. Other gastrointestinal effects from morphine include decreased appetite, constipation and vomiting.

Morphine Contraindications

Dogs taking monoamine oxidase inhibitors for depression should not take morphine. These two drugs together can produce a dangerous drug interaction. Aged cheese can produce the same interaction when consumed with morphine.

Dogs with breathing difficulties such as asthma or lung disease should not take morphine, which can slow or stop their breathing. If your pet has kidney, heart, liver, lung, thyroid or glandular disease, your vet may or may not prescribe morphine, as it can aggravate the symptoms of these diseases.

Morphine is not recommended for dogs who are old or debilitated, or have head injuries -- it can drastically lower body temperature in canines.

Veterinary Visit

Watch your canine companion closely for several days when he starts taking morphine. He will likely appear sleepy. Make certain he can't fall down stairs or hurt himself in his drowsy state. If you notice severe side effects ,such as labored breathing, diarrhea, constant sleeping, vomiting or a decrease in appetite, take him to your veterinarian. He may not respond well to morphine; the vet may prescribe a different type of pain relief that produces fewer side effects.