Melatonin for Dogs: Is It Safe?

PetMD Editorial
By PetMD Editorial
Published: March 13, 2017
Melatonin for Dogs: Is It Safe?

By Helen Anne Travis

Melatonin is a hormone that occurs naturally in the bodies of pets and people. As a supplement, it can help us and our canine companions relax, de-stress, and sleep. It may also help with certain medical conditions.

While you should always talk to your veterinarian before introducing any new medications or supplements into your pet’s health care regime, here are some ways melatonin, when administered properly, can help your dog feel healthier and happier.

Uses of Melatonin for Dogs


Melatonin is sometimes given to dogs who suffer from anxiety, says Dr. Judy Morgan, a holistic veterinarian and author of several books, including “From Needles to Natural: Learning Holistic Pet Healing.”

The supplement can help ease the symptoms of separation anxiety caused by long days at the office or a family vacation. It can also help a dog mellow out before a potentially stressful experience like a long road trip or a visit to the groomer.

Dr. Marie Haynes, a veterinarian in Ottawa, Canada, says she’s also seen melatonin help dogs who have thunderstorm anxieties.

“We use it whenever we need some sort of calming effect,” she says.


Melatonin is believed to help regulate the internal processes that tell our bodies whether it’s night or day, time to sleep or time to play. Humans may use melatonin supplements to overcome the insomnia associated with jet lag. It can also help older dogs with cognitive dysfunctions regulate their biorhythms and get a better night’s sleep, Morgan says.

Cushing's Disease

“What I use melatonin most commonly for is the treatment of Cushing's disease,” Morgan says. The supplement helps the body block the uptake of increased cortisone caused by a benign tumor on the pituitary gland, she says. Cushing’s disease can also be caused by a tumor on an adrenal gland. These cases are best treated through surgery, says Dr. Jennifer Coates, a veterinary advisor for petMD.

Other drugs used to treat pituitary-dependent Cushing’s disease can cause harsh side effects, including vomiting, diarrhea, and even kidney failure, although they typically become necessary when a dog has moderate to severe symptoms. “I like to start with something natural and take it from there,” Morgan says. Melatonin appears to be most helpful when dealing with mild cases of Cushing’s disease or with “atypical” Cushing’s disease, in which sex hormone production is elevated, Coates explains.


Haynes says she uses melatonin to help dogs suffering from seasonal alopecia, which is sometimes also referred to as flank alopecia. The condition is marked by bald patches on either side of the abdomen.

It’s not known what causes the hair loss, she says. It’s also not clear how melatonin helps seasonal alopecia, or if the condition would go away by itself without the use of the supplement. But for some pet owners, it’s satisfying to know they’re trying to do something to help their dog.

“There’s no scientific proof melatonin works, but the potential for serious side effects is very low,” Haynes says. “In most cases, there’s no harm in trying it.”

Melatonin Side Effects in Dogs

While melatonin is regarded as safe for most dogs, it’s still important to talk to your veterinarian before administering it to your pet.

Dosage will depend on the size of the dog and his sensitivity to the drug. It’s also important to run the supplement’s ingredient list by your veterinarian. Some brands of melatonin contain xylitol, which is poisonous to dogs, Haynes says.

The biggest side effect to melatonin is drowsiness. It can also cause digestive upset and, in some animals, an increased heart rate. It may also affect the reproductive cycle of female dogs and can cause insulin resistance in diabetic animals.

It’s also important to speak to your veterinarian to make sure the supplement doesn’t interact with other medicines your dog is taking.

And just like any medication, melatonin could cause an allergic reaction in your dog, Morgan says. “I’ve never seen it happen, but it’s something to watch out for.”

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