Melatonin is a hormone that is produced by a small gland in the brain called the pineal gland. Melatonin is sometimes given as an oral supplement to manage a variety of conditions in both humans and animals.
In veterinary medicine some of the indications include dermatologic conditions (hair loss), sleep disturbances / nocturnal activity, hyperadrenocorticism (Cushing’s Disease), regulation of estrus in breeding animals, as well as fears and phobias.
In the case of animals with behavior issues, here is Dr. E'Lise Christensen's spin on the use of melatonin:
Species-specific uses and dosing are as follows:
Dogs:
Cats:
Ferrets:
Sheep, Goats, Horses - to seasonally control fertility
Safety: Melatonin supplementation is generally regarded as as safe. Side effects are uncommon but include sedation and reduced fertility. In humans, side effects include pruritus.
Interactions: Melatonin supplementation may potentiate the effects of benzodiazepines.
Dosing melatonin (Source: Plumbs Veterinary Drug Handbook - 7thedition):
Dogs:
- Alopecia-X: 3-6 mg (total dose) PO q8-12 h
- Recurrent flank or seasonal flank alopecia: 2-3 mg/dog PO qd x 3-5 days (weekly, or monthly, or as a daily dose)
- *Sleep disorders: 3-6 mg (total dose) PO q12-24 hrs
- ** Fear/phobia - 0.1 mg/kg PO q8h
Cats:
- Nocturnal activity: 3-12 mg (total dose) PO q12-24 h
- Estrus suppression: 18 mg implant SC (suppresses estrus 2-4 months)
Ferrets:
- 0.5-2 mg/ferret PO qd (administered 7 to 9 hrs after sunrise)
* If used to regulate the sleep-wake cycle, melatonin should be administered at night, 60 mins before bedtime.
** If used as part of the management of fears or phobias, melatonin should be administered 60 mins prior to the known trigger.
