What is Melatonin and how is it produced? 

This article covers the use of Melatonin in the dog. But exactly is this drug? Well, Melatonin is a class of drug called a neuro-hormone, although I call it a drug as far as vets and pet owners go you are really dealing with something which is actually more of a food supplement. There are two types you might encounter, the first is the natural form, and the second is a synthetic, { manmade } form.

Natural melatonin is made from the pineal gland of animals. There is a worry that this form could potentially be contaminated with a virus or indeed a sub-viral particle, so personally, I would avoid this form.

How is Melatonin used in the dog?

Melatonin has been used in the treatment of separation anxiety in dogs.

It is also used to treat other stressful conditions, such as noise anxieties related to fireworks etc.

This drug has been used to help sleep patterns in pets that are very active at night and not sleeping at the right time. This can sometimes occur in older dogs ( Sundowner Syndrome ) Basically it helps re-sets the animal’s biological clock.

It has been used to treat various other behavioural problems in dogs and it is known to have sedative properties.

Melatonin is sometimes used in dogs to treat some specific causes of baldness in the dog such as Bilateral Canine Flank Alopecia.

Other uses have been the treatment of dogs with blood { platelet } disorders.

It has sometimes been used in the past as an anticonvulsant.

It also appears to have properties as an antioxidant which will combat free radicals which may be important in some disease conditions

Also the suppression of estrus in cats

What are the dose rates for Melatonin in the dog? 

For smaller dogs, Melatonin is given at up to 1 mg per dog three times a day orally.

Medium-sized dogs can take a dose of up to 3 mg per dog three times a day. 

For larger dogs the dose rate of up to 9 mg dog orally. Again given three times a day.

Melatonin implants are available which can be injected subcutaneously in dogs by your vet. These can have a very long duration of action, sometimes more than six months and up to a year. This can be a very convenient way to give the drug.

The length of the course would depend on the response to treatment and any side effects which arise. That said his drug has often been safely used in dogs when given for long periods of time.

What are the dose rates for Melatonin in the cat? 

In cats, melatonin is dosed at between 1.5 to 6 mg per cat orally { total daily dose, not weight dependant } where indicated. This is usually given every 12 hours. The 18 mg implant has been used to suppress estrus in cats for 2 to 4 months.

What to do if a dog has accidentally taken an overdose of Melatonin?

As far as overdoses go I have known dogs accidentally swallow a great number of melatonin tablets and not suffer any adverse side effects of any sort. As I said this drug has an extremely high margin of safety in the dog. So in the event of an overdose, it is usually safe enough just to observe your dog for the time being and then contact your vet if you become further concerned. But this would be generally unlikely, you may perhaps see a minor stomach upset, but that’s about it.

Caution! Some over the counter human Melatonin formulations contain the artificial sweetener Xylitol.

This would be your main worry if a dog has accidentally swallowed human formula Melatonin. These tablets may contain Xylitol which is an artificial sweetener, which can be seriously toxic to dogs. If in doubt on this point contact a local ASAP.

Please follow this link for an article on the dangers of Xylitol in the dog, including emergency treatment: LINK

Are side effects possible if a dog is taking Melatonin?

This drug is generally considered to be very safe and few side effects have been noted, but like any drug allergic reactions are possible in a very small number of individuals. With a very small number of individuals excessive lethargy or paradoxically nervous behaviour was noted, but should this occur it is not likely to be serious. Lastly, some authorities are concerned that it can interfere with a female dog’s reproductive cycle.

Minor drug interactions are possible with such drug which your dog might be already taking such as sedatives, steroids and monoamine oxidase inhibitors.