What is the typical mirtazapine dose for a [dog](/knowledge/veterinary-medicine/clinical-methods/dog)?

The most current evidence supports an oral dose of 0.6 mg/kg once daily for appetite stimulation in dogs. This dose has been shown to be safe and effective in clinical studies.

# Mirtazapine Appetite Stimulant: Dose for Cats and Dogs Guide ## Key Takeaways - Mirtazapine is a dual-acting veterinary pharmaceutical, functioning as both an appetite stimulant and an anti-emetic, primarily indicated for inappetence in cats and dogs. - For cats, oral dosing typically ranges from 1.88 mg to 3.75 mg every 48 hours, with a lower dose (1.88 mg q48h) often preferred in cases of chronic kidney disease to mitigate side effects. - Dogs commonly receive mirtazapine orally at a dose of 0.6 mg/kg once daily, a regimen supported by recent clinical trials for short-term appetite stimulation. - Transdermal mirtazapine is an alternative for cats, with commercial formulations dosed at 0.5 mg/kg daily, offering a slower onset of action but improved owner compliance compared to oral administration. - Key side effects in cats include vocalization and restlessness, while dogs may experience mild sedation; caution is advised in patients with compromised liver or kidney function due to altered drug metabolism and excretion. - Mirtazapine is a prescription medication requiring veterinary diagnosis and oversight; it should not be administered without professional guidance, and prompt veterinary consultation is critical if a pet stops eating for over 24 hours. --- **Direct answer:** Mirtazapine is a veterinary appetite stimulant and anti-emetic used to manage inappetence in cats and dogs. For cats, the typical oral dose is 1.88 mg to 3.75 mg per [cat](/knowledge/veterinary-medicine/clinical-methods/cat) every 48 hours, while dogs commonly receive 0.6 mg/kg orally once daily. However, these are general guidelines; the exact dose, frequency, and formulation (oral vs transdermal) must be determined by a veterinarian based on the individual patient's health status, underlying disease, and concurrent medications. **Owner Triage Summary:** If your pet stops eating for more than 24 hours, contact your veterinarian immediately. Do not attempt to dose mirtazapine without a prescription. While this medication is generally safe, the correct dose is critical, especially for cats with kidney disease or liver disease. If your pet is also lethargic, vomiting, has diarrhea, or is showing signs of pain, seek urgent veterinary care. Mirtazapine is a prescription medication and requires a veterinarian's diagnosis to ensure it is appropriate for your pet's specific condition. ## At a Glance: Mirtazapine in Cats and Dogs | Feature | Cats | Dogs | | :--- | :--- | :--- | | **Primary Use** | Appetite stimulation, anti-emetic (especially with CKD and chemotherapy) [1][2][3] | Appetite stimulation, anxiety-related behaviours [4][5] | | **Common Oral Dose** | 1.88 mg to 3.75 mg per cat every 48 hours [6][2][3] | 0.6 mg/kg orally once daily [4] | | **Common Transdermal Dose** | 2 mg per cat every 24 hours (compounded) or 0.5 mg/kg (commercial ointment) [1][6][7] | Not routinely used; oral is preferred [4] | | **Onset of Action** | Oral: ~1-2 hours to peak plasma levels; transdermal: ~16 hours [7] | Not well-defined; effects seen within 24 hours in studies [4] | | **Frequency** | Every 24-48 hours depending on formulation and renal status | Once daily [4] | | **Key Side Effects** | Vocalization, restlessness, vomiting, redness at application site [6][8] | Mild sedation, increased appetite, occasional vomiting [4] | | **Monitoring** | Weight, appetite, kidney/liver values, behaviour changes [6][2] | Weight, appetite, behaviour [4][5] | ## Understanding Mirtazapine Mirtazapine is a tetracyclic antidepressant that is widely used in human medicine. In veterinary medicine, it has found a valuable role as an appetite stimulant and anti-emetic, particularly for cats [1][2][9]. Its mechanism of action involves antagonism at central alpha-2 adrenergic receptors and specific serotonin (5-HT2 and 5-HT3) receptors. This dual action is believed to be responsible for both its appetite-stimulating and anti-nausea effects [1][9]. While historically used off-label, mirtazapine is now a cornerstone of managing inappetence in small animal practice. The drug is available in both oral and transdermal formulations for cats, offering flexibility for owners who may find it difficult to administer pills [1][8]. In dogs, oral administration is the standard route [4]. ## The Physiology of Appetite and Inappetence Appetite is a complex process regulated by the central nervous system, particularly the hypothalamus, and involves a balance of orexigenic (appetite-stimulating) and anorexigenic (appetite-suppressing) signals. Inappetence, or anorexia, is a common clinical sign in sick animals and can be triggered by a variety of factors, including: - **Systemic Disease:** Chronic kidney disease (CKD), cancer, and liver disease are common causes of reduced appetite [1][6][2][10]. - **Gastrointestinal Issues:** Nausea, vomiting, and diarrhea can all lead to a refusal to eat. - **Pain:** Post-surgical pain or pain from other conditions can suppress appetite [11]. - **Stress and Anxiety:** Environmental changes, hospitalization, or behavioural issues can cause inappetence [5]. - **Medication Side Effects:** Certain drugs, such as chemotherapeutic agents, can induce nausea and anorexia [1][3]. Prolonged anorexia is particularly dangerous for cats, as they are prone to developing hepatic lipidosis, a potentially fatal condition of fat accumulation in the liver [9]. Therefore, prompt management of inappetence is crucial. ## Mirtazapine in Cats: A Detailed Look The evidence for mirtazapine's efficacy in cats is robust, especially for managing chronic kidney disease and chemotherapy-induced side effects. ### Dosing for Cats The dose of mirtazapine in cats is not a simple weight-based calculation. It is often dosed per cat due to its wide therapeutic index and the need to avoid excessive side effects. - **Oral Mirtazapine:** The most commonly cited oral dose is **1.88 mg per cat every 48 hours**. However, studies have used both 1.88 mg and 3.75 mg per cat effectively [6][2]. For cats with CKD, a lower dose of 1.88 mg every 48 hours is often recommended to reduce the risk of side effects like vocalization and restlessness [6]. - **Transdermal Mirtazapine:** This formulation is applied to the inner pinna (ear flap). A commercial product is dosed at **0.5 mg/kg once daily** [7]. Compounded transdermal gels have been studied at doses of **1.88 mg and 3.75 mg per cat every other day** [6]. The pharmacokinetics of transdermal administration differ significantly from oral, with a slower absorption and more prolonged half-life [7]. - **Use in Chemotherapy:** For cats undergoing chemotherapy, mirtazapine has been shown to be beneficial. One study used **1.88 mg per cat every 48 hours** to successfully reduce gastrointestinal side effects and improve appetite in cats receiving doxorubicin [3]. Another retrospective study evaluated the use of transdermal mirtazapine in cats with lymphoma receiving chemotherapy and found it to be well-tolerated and effective in preventing substantial weight loss [1]. ### Evidence for Use in Cats - **Chronic Kidney Disease:** Multiple clinical trials have demonstrated that both oral and compounded transdermal mirtazapine significantly increase appetite and body weight in cats with CKD [6][2]. These studies also noted improvements in food consumption rates and owner-assessed appetite scores. - **Chemotherapy-Induced Anorexia:** Mirtazapine's role as an anti-emetic and appetite stimulant is particularly valuable in feline oncology. A study by Lee and Wang (2024) found that cats receiving mirtazapine alongside doxorubicin chemotherapy had significantly higher body weights, better appetite scores, and fewer episodes of vomiting compared to those receiving a placebo [3]. - **Post-Operative Anorexia:** Research has shown that mirtazapine is more effective than a placebo at stimulating appetite in cats following ovariectomy surgery [11]. ## Mirtazapine in Dogs: Emerging Evidence The use of mirtazapine as an appetite stimulant in dogs is less established than in cats, but recent research is providing valuable data. ### Dosing for Dogs - **Oral Mirtazapine:** The most current evidence, from a 2025 study, used a dose of **0.6 mg/kg orally once daily** [4]. This study demonstrated that this dose was safe and effective in increasing food intake in dogs with reduced appetites. ### Evidence for Use in Dogs - **Appetite Stimulation:** A retrospective study and a placebo-controlled trial published in 2025 evaluated the short-term effects of mirtazapine in dogs with inappetence [4]. The results showed that dogs receiving mirtazapine were more likely to start eating and consumed more food than those on placebo, particularly on the first day of treatment. The study concluded that mirtazapine is a safe and helpful option for short-term appetite stimulation in sick dogs. - **Behavioural Issues:** Beyond appetite, mirtazapine has been investigated for its anxiolytic (anti-anxiety) properties in dogs. A review of 32 cases found that 81% of dogs with anxiety-related behavioural problems showed improvement when treated with mirtazapine, with only mild and tolerable side effects [5]. This suggests a potential dual benefit for dogs with stress-related inappetence. ## Oral vs. Transdermal Administration The choice between oral and transdermal mirtazapine is a key clinical decision, especially for cats. - **Oral Administration:** This route provides a rapid onset of action, with peak plasma levels reached in about 1-2 hours [7]. It is generally more cost-effective. However, it can be challenging to administer to uncooperative cats. - **Transdermal Administration:** This route is applied to the inner ear and is often easier for owners [8]. The onset of action is much slower, with peak plasma levels not reached until about 16 hours after application [7]. The relative bioavailability of the commercial transdermal ointment is about 65% compared to the oral form, meaning the body absorbs less of the drug [7]. Compounded transdermal formulations may have variable absorption, and their efficacy has been shown to be comparable to oral forms in some studies [6]. Owner surveys indicate that while transdermal application is generally preferred for ease, some owners prefer the oral form due to its lower cost [8]. ## Safety, Side Effects, and Contraindications Mirtazapine is generally well-tolerated in both cats and dogs, but it is not without potential side effects. ### Common Side Effects in Cats - **Vocalization:** Increased meowing is a well-documented side effect, particularly at higher doses [6][8]. - **Restlessness and Hyperactivity:** Some cats may become more active or agitated [6][8]. - **Vomiting:** Although it is an anti-emetic, mirtazapine can occasionally cause vomiting in some cats. - **Application Site Reactions:** For the transdermal form, redness or irritation at the application site on the ear has been reported [8]. - **Sedation:** While less common, some cats may become sedated, especially at the start of treatment. ### Common Side Effects in Dogs - **Sedation:** This is a more frequently reported side effect in dogs, especially at higher doses [5]. - **Increased Appetite:** This is the desired effect but can be excessive in some animals. - **Gastrointestinal Upset:** Vomiting or diarrhea can occur, though it is not common [4]. ### Contraindications and Precautions - **Liver Disease:** Mirtazapine is metabolized by the liver. Caution is advised in animals with severe liver disease, and dose adjustments may be necessary. - **Kidney Disease:** While mirtazapine is used to treat anorexia in CKD, the dose should be reduced in cats with severe kidney disease because the drug's half-life is prolonged, increasing the risk of side effects [6][2]. - **Pregnancy and Lactation:** The safety of mirtazapine in pregnant or nursing animals has not been fully established. It should only be used when the benefits clearly outweigh the risks. - **Monoamine Oxidase Inhibitors (MAOIs):** Mirtazapine should not be used concurrently with MAOIs due to the risk of severe drug interactions. ## Evidence-Based Management of Inappetence Mirtazapine is a powerful tool, but it is not a substitute for diagnosing and treating the underlying cause of anorexia [9]. 1. **Veterinary Diagnosis:** The first step is always a thorough veterinary examination to identify the root cause of the inappetence. This may involve blood work, urinalysis, imaging, or other diagnostics. 2. **Underlying Disease Management:** The primary goal is to treat the underlying condition, whether it is CKD, cancer, or an infection [9]. 3. **Pharmacological Support:** Mirtazapine can be used as a symptomatic treatment to encourage food intake while the primary disease is being addressed [1][2][4][3]. 4. **Nutritional Support:** In cases of severe or prolonged anorexia, other nutritional interventions may be necessary, such as feeding tubes, to ensure the patient receives adequate calories [4]. 5. **Monitoring:** Regular monitoring of body weight, appetite, and overall condition is essential to assess the effectiveness of the treatment plan [6][2]. ## Unsafe Home Remedies and What to Avoid When your pet is not eating, it is tempting to try various home remedies. However, many can be unsafe or ineffective. - **Do Not Use Human Medications:** Never give your pet human appetite stimulants or antidepressants without veterinary approval. Doses and formulations are different. - **Avoid Force-Feeding:** Force-feeding a nauseated or anorexic pet can cause aspiration pneumonia and create a severe food aversion. - **Do Not Offer Unsafe Foods:** Avoid giving your pet foods that are toxic, such as chocolate, onions, grapes, or xylitol-containing products, in an attempt to entice them to eat. - **Do Not Delay Veterinary Care:** If your pet has not eaten for more than 24 hours, especially if they are also vomiting or lethargic, do not wait to see if they improve. Early intervention is critical. ## Prevention and Prognosis Prevention of inappetence focuses on managing underlying chronic conditions and minimizing stress. - **Regular Veterinary Check-ups:** Routine wellness exams can help detect diseases like CKD early, allowing for timely intervention. - **Stress Reduction:** For pets prone to stress-related anorexia, maintaining a consistent routine, providing a quiet feeding area, and using pheromone diffusers may be helpful. - **Palatable Diets:** Offering highly palatable, high-quality diets can help maintain interest in food. The prognosis for a pet with inappetence depends entirely on the underlying cause. For conditions like CKD, mirtazapine can significantly improve quality of life by promoting food intake and weight stability [6][2]. In cancer patients, managing anorexia can improve both quality of life and potentially survival times [10]. For acute, short-term inappetence, such as after surgery, the prognosis is generally excellent with supportive care [11]. ## Limitations and When to Contact a Veterinarian This guide provides general information and should not be used as a substitute for professional veterinary advice. The information presented here cannot predict how an individual animal will respond to mirtazapine. Breed, age, genetic predispositions, and the specific nature and severity of the underlying disease all influence the safety and efficacy of this medication. **Contact your veterinarian immediately if:** - Your pet has not eaten for more than 24 hours. - Your pet is vomiting, has diarrhea, or shows signs of abdominal pain. - Your pet is lethargic, weak, or collapsing. - You observe any severe side effects after administering mirtazapine, such as excessive agitation, tremors, or difficulty breathing. - Your pet's condition does not improve within 48 hours of starting treatment. Do not adjust the dose or frequency of mirtazapine without consulting your veterinarian. Overdosing can lead to serious neurological and cardiovascular signs. ## Frequently Asked Questions ### 1. What is the typical mirtazapine dose for a cat? The typical oral dose for a cat is 1.88 mg to 3.75 mg per cat every 48 hours. For cats with kidney disease, a lower dose of 1.88 mg every 48 hours is often recommended [6][2]. A commercial transdermal ointment is dosed at 0.5 mg/kg once daily [7]. ### 2. What is the typical mirtazapine dose for a dog? The most current evidence supports an oral dose of 0.6 mg/kg once daily for appetite stimulation in dogs [4]. This dose has been shown to be safe and effective in clinical studies. ### 3. How quickly does mirtazapine work to stimulate appetite? Oral mirtazapine reaches peak plasma levels in about 1 to 2 hours, so its appetite-stimulating effects can be seen within a few hours [7]. The transdermal formulation is slower, with peak levels not reached until about 16 hours after application [7]. ### 4. Can mirtazapine be used to prevent vomiting in cats? Yes, mirtazapine has anti-emetic properties. Studies have shown it is effective in reducing vomiting episodes in cats undergoing chemotherapy [1][3]. It is often used as an adjunct to other anti-emetics. ### 5. Is transdermal mirtazapine as effective as the oral form? Studies have shown that compounded transdermal mirtazapine can be effective in stimulating appetite in cats with CKD [6]. However, the commercial transdermal ointment has a lower bioavailability (about 65%) compared to the oral form, meaning it is absorbed less efficiently [7]. Both are viable options; the choice depends on the patient and owner preference [8]. ### 6. What are the most common side effects of mirtazapine in cats? The most commonly reported side effects in cats are increased vocalization, restlessness, and occasional vomiting [6][8]. Redness at the application site can occur with the transdermal form [8]. These effects are often dose-dependent. ### 7. Can I give my dog mirtazapine that was prescribed for my cat? No, you should never give medication prescribed for one pet to another. The dose for dogs and cats is different, and the underlying medical conditions may not be the same. Always consult your veterinarian before administering any medication. ### 8. What should I do if my pet stops eating? If your pet stops eating for more than 24 hours, contact your veterinarian immediately. Do not wait to see if they improve. Prompt diagnosis and treatment of the underlying cause are essential, especially for cats, who can develop serious complications like hepatic lipidosis [9]. ## Sources [1] [Appetite Stimulant and Anti-Emetic Effect of Mirtazapine Transdermal Ointment in Cats Affected by Lymphoma Following Chemotherapy Administration: A Multi-Centre Retrospective Study](https://www.semanticscholar.org/paper/20fc7296a4f67104d8723158adbd245f4bbc26af) [2] [Mirtazapine as an appetite stimulant and anti-emetic in cats with chronic kidney disease: a masked placebo-controlled crossover clinical trial.](https://www.semanticscholar.org/paper/d1f308c07ead66e0edeacde3e92f102d86023edb) [3] [Oral mirtazapine decreases the gastrointestinal adverse effects in cats on doxorubicin chemotherapy.](https://www.semanticscholar.org/paper/5c4fcb48159ddefe27aeef2a3c6f9e8935728657) [4] [Evaluation of the Short-Term Effects of Mirtazapine on Appetite Stimulants in Dogs: A Retrospective Study and a Placebo-Controlled Trial](https://www.semanticscholar.org/paper/6d53267b952d402977b53058780aa8016d124214) [5] [Use of mirtazapine in the treatment of canine behaviour problems: A review of 32 cases.](https://www.semanticscholar.org/paper/f73b0fbfc1bf7dd98abb2aaf568cf48f61089213) [6] [Assessment of compounded transdermal mirtazapine as an appetite stimulant in cats with chronic kidney disease](https://www.semanticscholar.org/paper/3926c3d444dc1594acaff78bacf862c1719b0073) [7] [Single and multiple dose pharmacokinetics of a novel mirtazapine transdermal ointment in cats.](https://pubmed.ncbi.nlm.nih.gov/30004120/) [8] [Owner’s Perspective About the Use of Mirtazapine Transdermal Ointment in Cats—A Survey-Based Study](https://www.semanticscholar.org/paper/5a07fea7d2b0c225c6c6ce26c164453d15abfd1e) [9] [Pharmacological appetite stimulation: rational choices in the inappetent cat.](https://pubmed.ncbi.nlm.nih.gov/25146662/) [10] [Anorexia and the Cancer Patient.](https://pubmed.ncbi.nlm.nih.gov/31176457/) [11] [Appetite-stimulating effect of gabapentin vs mirtazapine in healthy cats post-ovariectomy](https://www.semanticscholar.org/paper/bb7298a7f073b0ec85efd925a6b59766e6d08f4d) [12] [Mirtazapine as Appetite Stimulant in Patients With Non-Small Cell Lung Cancer and Anorexia: A Randomized Clinical Trial.](https://www.semanticscholar.org/paper/ba37ba6ca3c872a398a168024c9cf1887e5b521e) [13] [Preliminary Pharmacokinetics and Appetite Stimulant Efficacy of Oral Mirtazapine in Guinea Pigs (Cavia porcellus)](https://www.semanticscholar.org/paper/5df1f52ba4a7d2ed823d35f3f2c3b3124db4305c) [14] [Use of mirtazapine for appetite stimulation and weight gain in cancer-associated cachexia and anorexia: A systematic review.](https://pubmed.ncbi.nlm.nih.gov/42089744/) [15] [Clinical evaluation of efficacy and safety of appetizer syrup as appetite stimulant in children with non-pathogenic anorexia](https://www.semanticscholar.org/paper/1aecb7897ed274ee42d9dcfc28c73ac36b75529d) [16] [Nonmedical prescription stimulant use for suppressing appetite and controlling body weight is uniquely associated with more severe eating disorder symptomatology.](https://www.semanticscholar.org/paper/9409f59c524137a17a8b7cb2308bdf40abcd4e98) [17] [Anorexia of aging in long term care: is dronabinol an effective appetite stimulant?--a pilot study.](https://www.semanticscholar.org/paper/db74b30af8ace05fd5b9e36d33fd5bd84702064f) [18] [Comparative evaluation of cyproheptadine and mirtazapine in enhancing post-surgical appetite in rabbits following ovariohysterectomy](https://www.semanticscholar.org/paper/89747556f60568ce5d2b2213c1be7e7c5d3cdc93) [19] [Therapeutic Effects, Side Effects, and Adverse Effects of Neuropsychiatric Drugs in the Context of Treating Cancer-Related Anorexia With Olanzapine and Mirtazapine.](https://www.semanticscholar.org/paper/c1b648f0ede1ddcd32c6ac1107c480f23fba50cf) [20] [Pharmacotherapy for attention deficit/hyperactivity disorder in youth with avoidant restrictive food intake disorder: a case series of patients prescribed stimulant medication in a partial hospitalization program for eating disorders.](https://pubmed.ncbi.nlm.nih.gov/38111067/) ## Related Clinical & Scientific Guides * [Drontal Plus Dewormer: Broad-Spectrum Dose Guide by Weight](/knowledge/veterinary-medicine/calculators-clinical-tools/drontal-plus-dewormer-broad-spectrum-dose-guide-by-weight) * [Panacur Fenbendazole Dewormer: Dog Fecal Parasite Treatment Schedule](/knowledge/veterinary-medicine/calculators-clinical-tools/panacur-fenbendazole-dewormer-dog-fecal-parasite-treatment-schedule) * [Prednisolone for Cats: Feline Safe Steroid Dose and Autoimmune](/knowledge/veterinary-medicine/calculators-clinical-tools/prednisolone-for-cats-feline-safe-steroid-dose-and-autoimmune)