How Does Melatonin Affect Dogs? Side Effects Of Melatonin In Dogs Update 04/2024

Dogs have circadian rhythms that are similar to our own. Dogs, like humans, have a diurnal sleep schedule, in which they are more active during the day and more sedentary at night. Chronic discomfort and cognitive difficulties can also disturb a dog’s ability to sleep.

When melatonin supplements are linked to human health benefits, dog owners may question whether they can also benefit their beloved pet. Dogs may benefit from the usage of melatonin, despite a lack of study into its efficacy and utility in this regard.

What Is Melatonin?

To let our bodies know that it’s time to wind down for the night, the hormone melatonin is secreted by the pineal gland in our brains around sunset. In addition to reducing feelings of anxiety, melatonin has been shown to help calm the body. As a pill, chewable tablet, tea, or tincture, you can buy synthetic melatonin over the counter. For those with sleep disorders like insomnia, it’s a good place to start because it’s not too expensive.

How Does Melatonin Affect Dogs?

Dogs appear to benefit from the relaxing effects of melatonin in the same way that people do. Study participants who received melatonin before to surgery were calmer and required fewer doses of anaesthetic at the start of the procedure.

Melatonin has been demonstrated to have other benefits for canines outside its sedative properties. Another research of dogs found that those given melatonin suffered less early anesthesia than those who didn’t take melatonin. It was found that castration-induced imbalances in hormones can be corrected by administering melatonin to dogs who had been castrated.

Is Melatonin Safe for Dogs?

It is safe to feed your dog melatonin, according to the American Society for the Prevention of Cruelty to Animals (ASPCA). There is a low risk of negative side effects with melatonin. Lethargy upon rising the next morning is the most typical adverse effect. However, make sure that the melatonin you purchase does not contain any fillers or coatings that could be dangerous, as well as the sweetener xylitol, which can cause harm to dogs if consumed in excess.

It’s possible that melatonin will interact with other medications your dog is taking, but the risk of major adverse effects is low when using it alone. Do not give melatonin to your dog without first consulting your vet.

How Much Melatonin Should You Give Your Dog?

The amount of melatonin you should feed your dog is not well-documented in the scientific literature. Plumb’s Veterinary Drug Handbook recommends a dosage range of 3–6 mg for dogs with sleep problems. Plumb’s Handbook recommends 0.1 milligrams of melatonin per kilogram of body weight for dogs with anxiety disorders.

Consult with your dog’s veterinarian to determine the appropriate dosage based on their age, weight, and any other medical conditions or drugs they may be on. In the event that your vet advises you to give your dog melatonin, be sure to buy the correct dosage. Pre-measured supplement alternatives make administering the exact quantity to your pet a cinch.

When Should You Give Your Dog Melatonin?

Using melatonin to assist your dog rest before bedtime or before a veterinary appointment is best done two hours prior to the time of the operation. For best effectiveness, melatonin should be absorbed into your dog’s body during this time window.

How much melatonin can I give my dog?

When given in moderation, melatonin is safe for dogs. It’s always a good idea to consult with your veterinarian before administering any supplement or prescription to your pet. Pregnant dogs and puppies less than 12 weeks old should not be given melatonin. Your vet should be able to tell you how much melatonin your dog should be taking. Melatonin dose (up to 3 times a day) for dogs can be summarized as follows:

  • Dogs weighing less than 10 pounds should be fed a smaller portion. 1 milligram
  • Small to medium-sized dogs (10-25 pounds) should get 1.5 milligrams
  • Dogs weighing between 26 and 100 pounds should receive this medication. 3 milligrams
  • Large dogs should be fed a higher protein diet. In the range of 3 to 6 mg.

If you do decide to give your pet melatonin, be sure to check the label to ensure that it does not include any xylitol. Toxic to dogs, this popular artificial sweetener is widely used by humans. After the initial dose, keep a watch out for an adverse reaction, as with other new medications or supplements you administer to your dog. Melatonin begins working within 15 minutes of ingestion and lasts for roughly 8 hours.

What should I watch out for when giving my dog melatonin?

If you are using melatonin as a supplement, there are very few adverse effects to worry about. There are, however, possible adverse effects:

  • Digestive upset
  • Increased heart rate
  • Itching
  • Female reproductive cycle change
  • Confusion

Why Is Melatonin Prescribed for Dogs?

Any of the following conditions could warrant the use of melatonin:

  • Disordered sleep
  • Anxiety
  • Hair loss
  • Cushing’s disease

If your dog has cancer and is undergoing chemotherapy, your veterinarian may also recommend melatonin.

There are many non-drug treatments that can be used alongside melatonin for sleep and anxiety disorders such as noise phobias, such as fireworks or thunderstorms.

How Does Melatonin for Dogs Work?

The effectiveness of melatonin is dependent on your dog’s health, the condition being treated, and the length of time it has been administered.


Supplementing a dog’s diet with melatonin may aid in restoring his or her sleep cycle. This can be especially beneficial for older dogs with cognitive difficulties and for blind canines who are unable to see at night or in the morning.


Melatonin also helps to relax dogs that are overly agitated. Melatonin “may block dopamine,” the feel-good brain chemical, according to researchers at the British Small Animal Veterinary Congress. Anxiety is connected to excessive dopamine levels.

Hair Loss

It’s not clear exactly how melatonin helps dogs with hair loss. “Melatonin may work at a cellular level directly on the hair follicles,” explains Dr. Sue Paterson, a dermatology specialist, in Veterinary Practice.

Other Uses of Melatonin for Dogs

According to Dog Cancer Blog, melatonin aids in weight gain in cancer-stricken dogs by reducing the negative effects of chemotherapy. Chemotherapy has a significant impact on appetite, thus this is critical.

Melatonin may also assist dogs with Cushing’s disease, which is brought on by an excess of the stress hormone cortisol, by lowering cortisol levels, according to the University of Tennessee College of Veterinary Medicine.

Consult your veterinarian if you believe melatonin would be beneficial for your dog.

Side Effects Of Melatonin In Dogs

If melatonin is delivered correctly and at the recommended dosage, there are minimal known negative effects in dogs. As a result, it is generally preferred over tranquilizers or other medications because of its lack of negative effects.

There are, however, a few adverse effects to be aware of. As a result, your veterinarian may recommend a lesser dosage or a different course of action.

Some pets may encounter the following negative effects:

  • Constipation and stomach cramps are the result of this.
  • Fast heart rate (elevated heart rate).
  • Itching.
  • Confusion.
  • Fertility fluctuates from woman to woman.

Melatonin products’ labels should always be carefully read. There are several that include hazardous substances for dogs, such as xylitol, an artificial sweetener.

Melatonin might aggravate some medical issues and interact adversely with some drugs. Before giving your dog any kind of supplement or medication, you should always consult with your veterinarian.

Additionally, melatonin should be avoided by pregnant dogs and puppies.

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