Sertraline (Zoloft®) for Pets – Vet Dr Duncan Houston 🩺

Published: November 2024 • Revised: 2025

Introduction & Background

Vet Dr Duncan Houston here! 😊 Sertraline, better known by its brand name Zoloft®, is an SSRI commonly used in humans. Off‑label, it helps dogs and cats with anxiety, compulsive behaviors, and phobias. While not marketed for pets, it’s prescribed by veterinarians when needed. It comes in 25 mg, 50 mg, 100 mg tablets, and a 20 mg/mL oral solution; capsules in 150 mg and 200 mg sizes. Always follow your vet’s instructions carefully.

🐾 How Sertraline Works in Pets

Sertraline is a Selective Serotonin‑Reuptake Inhibitor (SSRI). It helps pets by:

• Increasing serotonin levels in the brain, promoting calm and emotional balance.
• Reducing compulsive or stereotyped behaviors like pacing, licking, or chewing.
• Treating anxiety-related conditions like separation anxiety, noise phobias, and OCD.

Though designed for humans, vets may prescribe the human-form when no pet-specific alternative is available. The prescription is tailored to the individual pet’s weight, needs, and health.

✅ Common Uses in Veterinary Medicine

• Fear & anxiety disorders: Thunderstorms, travel, vet visits.
• Compulsive behaviors: Excessive licking, tail chasing, hair chewing.
• Behavioral disorders: Noise phobias, flank sucking, shadow chasing.

📋 Prescribing & Administration

Your vet will:

1. Estimate a safe starting dose based on your pet’s weight and condition.
2. Prescribe the human-form Zoloft® tablet or oral solution.
3. Provide clear dosing intervals (usually once daily).
4. Schedule follow-up visits to assess behavior changes and side effects.

Give exactly as directed. Don’t stop suddenly—sertraline discontinuation can cause withdrawal signs like agitation, irritability, or confusion. 😊

🔬 Monitoring & Adjustments

Over 2–4 weeks, your vet will monitor your pet’s:

• Behavioral improvements
• Appetite, mood, energy level
• Possible side effects (diarrhea, vomiting)

If needed, the dose is adjusted gradually to find the sweet spot. It takes time, but it’s worth it for long-term relief.

⚠️ Side Effects of Sertraline in Pets

While sertraline is generally safe when used correctly, it may cause side effects in some pets, especially during the first few weeks. Keep an eye out for:

• 🐶 Gastrointestinal upset: Vomiting, diarrhea, and reduced appetite are the most common symptoms.
• 😴 Fatigue or lethargy: Your pet might seem a little sleepy initially as their system adjusts.
• 🩸 Bleeding risks: In rare cases, nosebleeds, bruising, or prolonged bleeding may occur.
• 😟 Behavioral changes: Agitation, increased anxiety, or disorientation can occur if dosage is too high or stopped abruptly.

📞 Contact your vet immediately if your pet experiences tremors, seizures, or extreme behavior changes.

💊 Interactions with Other Medications

Sertraline interacts with several medications and supplements. It’s vital to tell your vet everything your pet is taking—including natural products or over-the-counter remedies. ⚠️ The most concerning issue is serotonin syndrome, a potentially dangerous condition caused by too much serotonin in the brain.

🚫 Avoid combining sertraline with:

• 💊 Other SSRIs or SNRIs (like fluoxetine)
• 💉 Tramadol (pain reliever)
• 💧 Selegiline (cognitive dysfunction treatment)
• 🌿 Supplements like St. John’s Wort
• 🧠 Tricyclic antidepressants (clomipramine, amitriptyline)
• 🚫 MAO inhibitors

If any of these drugs are necessary, your vet will create a safe transition plan with a proper washout period. Never switch or combine medications without veterinary guidance. 🐾

📉 Withdrawal & Discontinuation

Don’t stop sertraline cold turkey. Suddenly discontinuing this medication can lead to withdrawal symptoms like:

• ⚡ Agitation
• ❌ Loss of appetite
• 🌀 Anxiety or confusion
• 📉 Lethargy

Your vet will guide you through a gradual tapering schedule to safely discontinue the medication when appropriate. ❤️

🧠 When Will You See Results?

SSRI medications take time to work. You might see improvements in your pet’s behavior after 2–4 weeks, but full effects may take 6–8 weeks. ⏳

Dr Duncan Houston’s pro tip: Be patient and consistent. Trust the process, and don’t skip doses. Most pets show noticeable improvement with time, proper dosing, and occasional behavioral support. 🐕‍🦺🐈

🐶🐱 Is Sertraline Safe for All Pets?

Sertraline is generally well tolerated, but it’s not right for every animal. Your vet will assess your pet’s:

• 💚 Liver health – Sertraline is cleared by the liver. Pets with liver disease may need a lower dose or different drug.
• 🩺 Overall health – Pets with seizure disorders or chronic conditions may require extra monitoring.
• 🐾 Current meds – Your pet’s medication list is key to avoiding interactions.

🗃️ Storage & Handling Tips

• 💊 Store tablets and oral solution at room temperature (around 77°F/25°C).
• 🚫 Do not refrigerate or expose to excess heat or moisture.
• 🐾 Keep all medications out of reach of pets and children.

📋 Summary: What to Remember

• ✔️ Sertraline is an SSRI that supports emotional wellness in pets with anxiety and behavioral issues.
• ✔️ Use only under veterinary guidance, and never stop the drug suddenly.
• ✔️ Monitor your pet for side effects and keep your vet updated on any concerns.
• ✔️ Patience is key! It may take weeks to see full effects. ⌛

🐾 Final Word from Dr Duncan Houston

If your pet’s fears, obsessions, or anxiety are holding them back from living their best life, there’s hope. 💚 Sertraline, when paired with consistent care and love, can be part of a happier future for your furry friend. As always, reach out to your vet before starting any new medication. You’re not alone—we’re here to help. 🐾

Need extra guidance? Visit AskAVet.com and download the free Ask A Vet App for 24/7 expert advice and care tips! 🐕📱🐈