Uses/Indications: Treatment of chemotherapy induced nausea and vomiting (CINV), anorexia, associated with renal failure (azotemia), congestive heart failure, gastrointestinal disorders, liver disease, or neoplasia.
Studies/Case Reports: For years, veterinarians have used B-vitamins and steroids for appetite stimulation in canines and benzodiazepines in felines. Pharmacy faculty at The Mississippi State College of Veterinary Medicine used mirtazapine in a dog after all other attempts at appetite stimulation had failed, and were pleased to find that appetite was almost immediately restored. Due to the vast improvement in the quality of life, the dog’s primary care veterinary clinic conducted a series of uncontrolled trials over 4 years in 24 dogs and 17 cats with GI symptoms that were marginally responsive to standard therapies. “Mirtazapine therapy led to a robust response in 12 animals, improvement compared with standard treatment in 16 cases, and an equivocal response in 13 animals. The most vigorous responses were observed in patients with chronic renal failure or receiving concurrent chemotherapy for neoplastic disease.”
Adverse Effects: Drowsiness/Sedation, Vocalization, Hypotension, Tachycardia (all-dose dependent)
Dosing: Dogs: 0.6mg/kg PO every 24 hours (not to exceed 30mg per day)
Dogs < 20lbs = 3.75mg PO every 24 hours
21 – 50lbs = 7.5mg PO every 24 hours
51 – 75lbs = 15mg PO every 24 hours
> 75lbs = 15mg PO every 12 hours or 30mg PO every 24 hours
Cats: 3 – 4mg PO every 72 hours
Monitoring Parameters: Adverse Effects, Clinical efficacy measured by the following parameters: increased appetite, decreased episodes of vomiting, and weight gain