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Amitriptyline, which goes by the brand name Elavil, is a medication that’s used to treat depression in people. When a veterinarian prescribes an antidepressant to a dog, often it’s due to anxiety or a behavioral issue. If your dog seems lethargic or inactive, you might describe them as being depressed. However, it’s not accurate to characterize a dog as having clinical depression.
Instead, a veterinarian may prescribe amitriptyline as an off-label treatment for generalized anxiety or separation anxiety in dogs. Off-label refers to when you administer a medication for something besides its FDA-approved uses. Although amitriptyline is a longstanding drug, it may not be a veterinarian’s first choice for resolving behavioral issues.
What Is Amitriptyline, and How Does It Work?
Amitriptyline hydrochloride or amitriptyline is a human medication used in dogs for treating certain disorders and conditions, says Dr. Amy Attas, VMD of New York-based practice City Pets. These include behavioral disorders, anxiety disorders, chronic pain disorders, and urinary incontinence.
Since its FDA approval in 1961, amitriptyline has been used in medicine and veterinary medicine because it’s inexpensive, readily available, and doesn’t have many side effects, she says. Amitriptyline comes in oral tablets ranging from 10 mg to 150 mg. The dose is calculated based on your dog’s weight and may be given with or without food. Store tablets at room temperature and away from direct sunlight.
Amitriptyline belongs to a class of drugs called tricyclic antidepressants (TCA). These drugs work by blocking the reuptake of two neurotransmitters, serotonin and norepinephrine, which act as chemical messengers. By preventing their reabsorption, TCAs increase the level of serotonin and norepinephrine in the brain. “Higher levels of these neurotransmitters help regulate emotions, moods, and other physiologic functions,” Dr. Attas says.
Another way amitriptyline works is by blocking histamine, a chemical that the immune system produces. “If you have allergies, your body will release histamine, and what we take to decrease the effects of histamine are antihistamines,” she says. “So, even though amitriptyline has an antihistamine effect, it wouldn’t be the drug I would reach for if a pet had allergies.”
Uses of Amitriptyline in Dogs
“We use amitriptyline for separation anxiety, fear aggression, dominance aggression, obsessive-compulsive disorder, and inappropriate urination or defecation,” Dr. Attas says. A veterinarian may also prescribe amitriptyline to help with a phobia of noise, thunderstorms, or fireworks, as well as travel anxiety. Another use is to relieve nerve pain associated with osteoarthritis or intervertebral disc disease.
Since there are safer alternatives like training, calming supplements, and other medications, amitriptyline wouldn’t be the first choice for behavioral problems in dogs, she explains. Amitriptyline can, however, complement these methods. The best approach for treating anxiety, aggression, and phobias is behavior modification. This involves reducing stress and keeping dogs engaged through exercise, training, and mental stimulation.
“We want to use positive reinforcement to encourage the desired behavior and modify unwanted behaviors,” she says. For phobias, her advice is to use tools like desensitization or counter-conditioning. Desensitization means gradually exposing your dog to what they’re afraid of and repeating this process. Counter-conditioning aims to alter your dog’s response to something negative by pairing it with something positive, like a treat or toy.
If your dog is taking amitriptyline, she suggests giving them a natural supplement like melatonin or a dog appeasing pheromone. A pheromone is a chemical substance produced by the body that affects another member of a species like, for example, when dogs secrete sex pheromones that attract other dogs, she says. Dog appeasing pheromones work by simulating these naturally produced pheromones. They come in a spray, collar, or plug-in and are very effective at reducing stress and anxiety in dogs, but they don’t affect people or other pets, she says.
Side Effects and Drug Interactions
When used alone, amitriptyline doesn’t usually lead to side effects. Still, avoid using the drug in puppies, pregnant or lactating dogs, and seniors to be safe. If side effects do occur, they may include the following:
- Drowsiness or mild sedation
- Vomiting
- Decreased appetite
- Dry mouth
- Constipation
- Urinary retention
- Dry eyes accompanied by mucous discharge
- Rapid or irregular heart rate
Another caution when using amitriptyline is the potential to interact negatively with other medications. “Because its mechanism of action is increasing serotonin and norepinephrine, we can’t use amitriptyline with drugs that increase the level of neurotransmitters in the brain,” Dr. Attas says. These include selective serotonin reuptake inhibitors like Prozac, monoamine oxidase inhibitors, and sedatives like Trazodone.
“If those levels get too high, it causes a condition called serotonin syndrome and that can be really dangerous.” Serotonin syndrome is a serious drug reaction that can lead to high blood pressure, rapid heart rate, loss of muscle control, and even death. Avoid amitriptyline if your dog has a sensitivity to TCAs or has been diagnosed with hyperthyroidism since it can have toxic effects if combined with thyroid hormone supplementation.
Moreover, you should also avoid combining amitriptyline with clonidine, antihistamines, barbiturates, and opioids like Tramadol, she says. Other conditions for which you would exercise caution are seizure disorders, liver disorders, heart arrhythmias, diabetes, and dry eye.
What Happens If You Miss a Dose or Give Too Much?
Whenever you’re working with more than one expert such as a veterinarian and a behavior specialist, “be very clear on what drugs your dog is currently taking and the doses because we wouldn’t want to add two of the same categories of drugs,” Dr. Attas says. Before introducing a medication of the same class, you’ll need to reduce the dosage of the current medication. Then, there will be a “washout period,” which eliminates the drug from your dog’s system.
Because amitriptyline for dogs is used off-label, follow your veterinarian’s instructions carefully. It can take days or weeks before the medication has a noticeable effect on your dog’s behavior, but side effects may appear much sooner. “If a dose is missed, you would restart with the next dose,” she says.
Talk with your veterinarian before stopping this medication, as there may be important reasons to continue its use. You must taper off amitriptyline slowly or your dog may suffer uncomfortable withdrawal symptoms including vomiting, anxiety, and shaking.
Avoid giving your dog a catch-up dose or doubling the amount since this can lead to an overdose. Signs of an overdose include a lack of coordination, vomiting, rapid heart rate, or lethargy. If this happens, contact the ASPCA Animal Poison Control Center at 888-426-4435. The hotline is available 24 hours a day and there is a charge for this service.
When you call the hotline, provide information about your dog’s breed, weight, and the type and amount of medication or toxin consumed. They will create a file that your veterinarian can use to recommend a treatment plan based on how much of the toxin your dog ingested, she says.
This article is intended solely as general guidance, and does not constitute health or other professional advice. Individual situations and applicable laws vary by jurisdiction, and you are encouraged to obtain appropriate advice from qualified professionals in the applicable jurisdictions. We make no representations or warranties concerning any course of action taken by any person following or otherwise using the information offered or provided in this article, including any such information associated with and provided in connection with third-party products, and we will not be liable for any direct, indirect, consequential, special, exemplary or other damages that may result, including but not limited to economic loss, injury, illness or death.