Mirtazapine Use in Dogs As an Appetite Stimulant

Mirtazapine is the generic name for the brand name drug, Remeron. It̵7;s used to treat moderate and severe depression in humans, but is most useful for dogs because of its other properties. Veterinarians generally prescribe mirtazapine to dogs experiencing loss of appetite and nausea associated with various medical illnesses.

  1. How Mirtazapine Works

    • According to Mar Vista Animal Medical Center, mirtazapine stimulates a dog's appetite. Its anti-nausea properties actually intercept and block signals from the intestine and stomach to the brain that otherwise would trigger nausea. As a result, the dog doesn̵7;t experience these effects.

    How It's Used

    • The drug is usually administered to dogs suffering from conditions or treatments that cause a dog to lose its appetite or feel queasy. It̵7;s also prescribed to dogs being treated for cancer to ease upset stomachs.

    Dosage

    • Veterinarians generally prescribe mirtazapine once a day to stimulate appetite, which makes it easy and convenient for dog owners to administer. When the drug is prescribed to accompany treatment for kidney or liver disease, the dosage may be reduced further, as these conditions prevent the body from fully eliminating the drug as waste. Veterinary Partner says it̵7;s possible for up to 30 percent of the drug to remain in the body after normal elimination due to impaired liver and/or kidney function. Under these circumstances, a veterinarian will adjust the dosage.

    Side Effects

    • One potential yet rare side effect is serotonin syndrome, caused when serotonin levels -- a chemical found in the brain -- become elevated. This usually occurs when mirtazapine is used as part of a combination of other serotonin-increasing medications. Monitor your dog for elevated heart rate, tremors, dilated pupils, difficulty breathing, fever or high blood pressure, which all can be signs of serotonin syndrome. Hyperactivity also can be a sign in some dogs.

    Drug Interactions

    • Mirtazapine therapy can have adverse side effects when used in combination with antidepressants like Prozac that are meant to increase brain serotonin levels.