Melatonin Side Effects in Dogs

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Melatonin Side Effects in Dogs
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Potential side effects of melatonin use in dogs include drowsiness and interference with various hormonal effects in females. The natural hormone is commonly given to dogs who have separation anxiety and noise phobia. Melatonin comes in tablet form.


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Melatonin Use in Canines

Melatonin is a neurohormone secreted during the dark hours of the night by the pineal gland located in the center of the brain. It's also an antioxidant, which has the ability to fight free radicals -- particles associated with brain deterioration. Melatonin plays a major role in controlling reproductive cycles and body rhythms, ensuring their efficiency. As a medication, melatonin has anticonvulsant and sedative effects, as well. Veterinarians regularly recommend melatonin for use in dogs who display behavioral problems when their owners are away from home. They also regularly advise its use in dogs who suffer from intense anxiety triggered by noise -- think thunderstorms. Sometimes melatonin is given to canines who have hair loss resulting from Cushing's disease.


Although people can acquire melatonin over the counter, it should only be given to dogs with vigilant veterinary permission and direction. The FDA (U.S. Food and Drug Administration) has not approved the drug for pet use; however, veterinarians are permitted to prescribe it as an extra-label medication.


Potential Side Effects

When used under veterinary supervision, melatonin is typically safe and has few side effects. Some pets, however, may experience side effects, which include:

  • Intervening with hormonal effects in female dogs
  • Sleepiness
  • Slight stomach upset


If you own an intact female dog, melatonin use may change when she goes into heat, although not significantly. It also may affect her urge to mate.

Melatonin and Caution

This hormone is not suitable for all canines. It has the potential to interact with drugs such as tranquilizers, sedatives, corticosteroids and monoamine oxidase inhibitors. Make sure your veterinarian knows all of the medications and nutritional supplements your dog is taking before giving him melatonin.


Melatonin is also not suitable for use in dogs who have allergies or hypersensitivities to it. It's not appropriate for breeding canines either, due to its ability to change the specific time a female goes into heat. Since melatonin can affect the regulation of blood sugar, veterinarians should be heedful about recommending it for dogs who have diabetes.


Never give your dog melatonin without first speaking with your veterinarian. Melatonin products for people are typically significantly stronger than the amounts that benefit canines. Closely follow your veterinarian's dosage and administration instructions. Melatonin dosages for dogs are often based on their sizes. If your dog overdoses on melatonin, he could experience symptoms such as:


  • Vomiting
  • Diarrhea
  • Loss of coordination
  • High blood pressure
  • Seizures

If you're concerned that your pet may have overdosed on melatonin, seek emergency veterinary attention immediately.


If your vet prescribes melatonin for your dog, give him the full prescription unless she explicitly instructs you to stop using it early.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.



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