Unintended Weight Loss in Cats: When Nutrition Complicates Disease Management

November 13, 2018

Nutrition can be an important part of disease management.1 Cats have unique nutritional requirements that can bring complexity to recovery and healing.

“It’s an interconnected problem, especially in feline medicine where the tolerance to periods of poor nutrition is so low,”2 notes Christina Fernandez, DVM, MRCVS, DACVECC, Professional Services Veterinarian with Kindred Biosciences, Inc. “Cats experiencing disease can easily slip into a state of malnutrition that can lead to unintended weight loss. It’s one more challenge veterinarians and cat owners must address to help the cat recover.”

In fact, prolonged inadequate nutrition may be more detrimental to the patient than the primary disease process.2 Cats have special dietary needs compared to many other animals, including higher protein and amino acid requirements2,3 and a reduced ability to digest protein and fat.4 Recognizing feline weight loss early is critical to minimizing complications associated with the underlying disease.

It’s important to recognize weight loss early. Early identification may lead to improved response to therapy, reduced hospital stays, and ideally support at home with the owner.

“A cat is typically most comfortable in its own environment,” Dr. Fernandez says. “Although it’s not always possible, home care for management of both the primary disease and weight loss is ideal. The in-home plan should be suitable for both the cats’ condition and the owner or caretaker to result in the best chance of success.”

It’s helpful when medications to help manage unintended weight loss in cats are easy to administer for pet owners, she adds. Otherwise, the treatment plan can put additional strain on both the cat and owner during an already stressful time.

A recently approved product — Mirataz® (mirtazapine transdermal ointment) — is the first and only FDA-approved transdermal medication for the management of weight loss in cats. The topical application doesn’t rely on the cat’s willingness to eat to be medicated.

Until the approval of Mirataz, veterinarians had to rely on extra-label medications to manage weight loss in cats, including human oral mirtazapine tablets that may have inconsistent results.5

Route of administration is important for practitioners too. In a survey, 74 percent of veterinarians said ease of administration is one of the most important factors in selecting a medication for the management of unintended weight loss in cats.6

“Weight loss isn’t just another symptom,” Dr. Fernandez explains. “It’s a serious problem that complicates the underlying disease and makes recovery more difficult. Pet owners need convenient forms of medications to help them implement a treatment plan. Together, veterinarians and owners can work to achieve optimum health for our feline friends.”

Mirataz is indicated for the management of weight loss in cats.

Important Safety Information

Mirataz® (mirtazapine transdermal ointment) is for topical use in cats only under veterinary supervision. Do not use in cats with a known hypersensitivity to mirtazapine or any of the excipients. Do not use in cats treated with monoamine oxidase inhibitors (MAOIs). Not for human use. Keep out of reach of children. Wear gloves when handling/applying, wash hands after and avoid contact between the treated cat and people or other animals for 2 hours following application. Use with caution in cats with hepatic and kidney disease. Cat’s food intake should be monitored upon discontinuation. Safety has not been evaluated in cats less than 2 kg, less than six months of age or in breeding, pregnant or lactating cats. The most common adverse reactions observed during clinical trials were application site reactions, behavioral abnormalities (vocalization and hyperactivity) and vomiting. For product label, including complete safety information, click here.


1. Sanderson SL. Nutrition in disease management in small animals. Merck Veterinary Manual website. https://www.merckvetmanual.com/management-and-nutrition/nutrition-small-animals/nutrition-in-disease-management-in-small-animals. September 13, 2019.

2. Agnew W, Korman R. Pharmacological appetite stimulation: rational choices in the inappetent cat.
J Feline Med Surg. 2014;16(9):749-756.

3. Chan DL. The inappetent hospitalised cat: clinical approach to maximising nutritional support.
J Feline Med Surg. 2009;11(11):925-933.

4. Laflamme DP. Nutrition for aging cats and dogs and the importance of body condition. Vet Clin North Am Small Anim Pract. 2005;35(3):713-742.

5. Benson KK, Zajic LB, Morgan PK, et al. Drug exposure and clinical effect of transdermal mirtazapine in healthy young cats: a pilot study. J Feline Med Surg. 2017;19(10):998-1006.

6. 2017 Mirataz Pricing Research, Kynetec, September 2017 (n=204 U.S. small animal veterinarians). Data on file Kindred Biosciences. American Pet Products Association (APPA), 2017-2018 National Pet Owners Survey (n=22,202 respondents).