Prozac For Dogs: Everything You Need To Know 


Table Of Contents


Prozac, or fluoxetine, is an antidepressant in a class known as serotonin reuptake inhibitors or SSRIs. Medical doctors and veterinarians use this class of medication for other things too, including anxiety, phobias, and to help mood stability.

Drugs like Prozac started as human drugs but have been tested in dogs and work to help with the same problems.


Small animal veterinarians commonly prescribe Prozac for pets, including dogs. Much of Prozac's use in dogs is off-label, meaning that the FDA does not approve it for those uses. That said, veterinarians prescribe many drugs for non-FDA-approved uses.

This is called “off-label" use. If studies and the veterinarian's professional judgment show that a given drug is safe and effective, off-label use is considered an acceptable practice by most doctors and veterinarians.

Dogs have used Prozac for over 30 years, and it is considered safe and effective, although it may cause intolerable side effects in many dogs.


Prozac works the same way in dogs as it does in humans: It causes the brain to use serotonin in a way that usually leads to less anxiety, depression, and fear.

Many dogs will suffer from anxiety, especially those kept indoors or who do not get enough exercise for their breed type. These can include separation anxiety, thunderstorm anxiety, or anxiety bound up with overpowering fears (phobias). Prozac can help relax these anxieties and fears by increasing the amount of serotonin the brain uses.

General Anxiety

Dogs rarely suffer from general anxiety. Usually, it’s tied to a specific trigger or situation, like loud sounds, new environments, separation from their owner, car rides, going to the vet's office or groomer’s, etc. Most dogs will have some anxiety over some of these events, but very anxious dogs may have overpowering anxiety that leads to unwanted behaviors like damaging property, barking loudly, or resisting necessary treatment or grooming.

That said, dogs can suffer from age-related anxiety related to the loss of cognitive function. Dogs lose memory, awareness, and perceptive ability as they age, just like humans. They aren’t able to learn and adapt to new situation as quickly, and this can lead to anxiety and quarrelsome behavior.

Prozac can help with age-related anxiety in dogs by helping them feel calmer and more relaxed.

Separation Anxiety

Separation anxiety is one of the most common types of anxiety in dogs, especially indoor dogs. When the owner leaves, the dog barks, destroys furniture, urinates and poops where they shouldn't, and otherwise acts out in ways they wouldn't if someone was home. This is unavoidable for some dog owners who have to leave a dog alone in an apartment or house while they go about daily activities. Prozac's relaxing effects can help dogs stay calm in these situations.

Thunderstorm Anxiety

Louds sounds often trigger strong, anxious reactions in dogs. Thunder, gunfire, fireworks, and loud construction sounds can trigger anxiety. Prozac's calming effects help dogs endure these triggers without getting as excited and can help moderate their reactions.

Peeing Behaviors

Some dogs will urine-mark the house even without an obvious trigger like separation. This unwanted urination can be because of sexual drive, lack of exercise, lack of bladder control, general age-related anxiety, or other factors (or many factors at once!). Prozac helps with the aspects related to anxiety, calming and relaxing the dog, so it's less likely to want to urinate.


Anxiety can cause or enhance aggression in dogs, including age-related anxiety. Aggression describes any behavior where a dog threatens harm to another individual by barking, snarling, growling, snapping, or engaging in harmful behavior like lunging and biting. Prozac can help decrease this background anxiety, leading to a lower risk of aggressive behavior.

Phobias (fear disorders)

Phobias are irrational, usually intense fears that result from previous unpleasant experiences. In humans, irrational fears of height, needles, or spiders are common. In dogs, phobias are often related to loud sounds like gunfire, fireworks, or thunder.

They can also be related to needles and blood injections, severe separation anxiety, and fear of strangers – especially those they may view as similar to someone that abused them in the past. Prozac can help calm these phobias by reducing the anxiety levels the dog feels when exposed to an event that triggers their fears.

Compulsive Disorders

Compulsive disorders are more common in humans than dogs and can be tricky to diagnose. Dogs with CCD (Canine Compulsive Disorder) engage in behavior that's usually normal for dogs, but to an excess that becomes harmful.

A veterinarian can help you distinguish between normal excited behavior and genuine CCD. Experts think CCD arises from mismanagement of serotonin in the canine brain, much like OCD (Obsessive Compulsive Disorder) in humans. Drugs like Prozac were designed to help correct that imbalance.


According to the Merck Veterinary Manual, the daily dosage for fluoxetine in dogs is 1mg/kg each day – so a 50kg dog would take 50mg. As this medication is only available with a prescription, your veterinarian will provide you with the appropriate dose on the label of the medication bottle.

In humans, the best time of day to take Prozac is usually in the morning. For dogs, the best time of day to give Prozac is at the same time each day, whenever is easiest to remember to give them the dose.


It takes 6-8 weeks for Prozac to take full effect, although it can start working after just a few days. It is not like some drugs that start working at full effect right away. As a dog owner, you'll know that Prozac is working based on whether your pet's unwanted behavior is improving or not.


Unfortunately, Prozac (like most drugs) can cause side effects in dogs. Watch your pet for any unusual signs of negative side effects in their behavior, especially for the first week. Here are some of the most common side effects to look for:

Not Eating: Loss of appetite is one of the more common side effects of Prozac in dogs. If your dog suddenly doesn’t want their food after starting Prozac, discuss this with your veterinarian.

Prozac Made My Dog Worse: Prozac can cause or worsen aggression and anxiety. It corrects a specific type of serotonin imbalance in the canine brain, and if this imbalance is not the problem, it causes a serotonin imbalance.

Upset Stomach: Many drugs cause upset stomach in people and in dogs. Prozac is no exception. Giving it with food can help this problem.


It's important to wean a dog off Prozac. Suddenly stopping Prozac dosing can cause withdrawal in dogs, leading to a rebound of unacceptable behavior that Prozac treated previously. A veterinarian can guide you in doing this safely with your dog.

Withdrawal from Prozac leads to relapse and rebound behaviors in humans and dogs if it's done too quickly. Called "withdrawal," a previously aggressive dog treated successfully with Prozac may become even more aggressive if the drug is withdrawn too fast. Work with your veterinarian to taper or wean the dog off Prozac gradually.


Training: Many of the reasons Prozac is used in dogs can be corrected by training and owner behavior modification. For example, many owners can mistakenly encourage anxious behavior by telling their pet “good boy” or “it’s okay” when they’re showing anxiety or a phobia about going to the vet or loud noises.

This encouraging behavior may even cause the dog to feel anxious or afraid when they hear that phrase. Talk to a veterinarian about how you can behave around, treat, and train your dog to be less anxious.

Exercise: Both humans and dogs can feel anxiety, worry, and stress when they do not get enough exercise. This author cares for an Australian Shepherd that is an absolute terror indoors, showing signs of aggression and phobia – unless he’s been able to run a few miles that day, in which case he lies down and snuggles with everyone. Some humans choose to life weights intensely primarily to help them sleep, one of the immediate effects of intense exercise. If your dog is an active breed, getting them enough exercise can be tough. Herding dogs and dogs bred for running may need to run for half an hour or more to meet their exercise needs, and without this, they will continue to display undesirable behavior.

Correct Underlying Causes: Underlying issues can cause some aggressions and anxieties, such as age-related cognitive decline. Drugs like selegiline can help correct cognitive decline and, in so, help reduce the anxiety or aggression it causes. A qualified veterinarian can only make these diagnoses – but if you have noticed that your pet's anxiety or aggression started as they aged and worsened with age, it's a great idea to bring this up with your veterinarian.

Other Medications: There are other SSRIs like Prozac that are used in dogs, including Celexa or citalopram, Paxil or paroxetine, and Zoloft or sertraline. They have many of the same pros and cons as Prozac, but some individual dogs may respond better to one or another or be less likely to experience negative side effects.

CBD: Cannabidiol, or CBD, has been reported individually by many owners (including some vets!) to help with anxiety, aggression, and other issues Prozac also treats. Unlike Prozac, it has not been reported to have as many or as severe side effects at the usual dosing – especially when using a high-quality, lab-verified extract that does not contain THC.

THC can be toxic to dogs even at low doses. CBD is a good option to discuss with your veterinarian in looking at options, especially if Prozac or other prescription medications cause intolerable side effects or are too expensive.

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biscuits story

Biscuit's Story

Chris Kjolseth | CEO, Relievet

To say Biscuit lived an active life would be an understatement. Ever since she was a puppy, she’d spend her days running and playing. I’d take her on walks, to the beach, and to dog parks.​​

Unfortunately, at age 10, she started to limp after trips to the dog park. It broke my heart to see her in pain doing what she loved the most. I started feeding her a raw food diet and added high-quality supplements to ensure her nutritional needs were met.

Unfortunately, while she loved the food, the limping...

Read Her Story

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