Table 1.

Dose, frequency and route of administration of exogenous melatonin administered to female and male cats and associated reproductive outcomes

Sample size (n)	Dose and route of administration	Cycle stage at initiation of treatment	Outcome	Reference
16 females	5 mg q48h SC	Not stated	Suppressed ovarian activity even under a 24 h light photoperiod for 60 days	20
6 females	30 mg q24h PO 3 h before lights off for 35 days	Not stated	Returned to estrus 33 ± 2.8 days (range 21–40 days) after treatment ended	2
4 females	60 mg (five 12 mg implants)	Not stated	Suppressed estrus in 75% (duration of estrus suppression not given)	21
9 females	18 mg (single implant)	During interestrus	Within 3–9 days of implant insertion, 33% had superficial cells present on their vaginal cytology and estrous behavior for 2 days followed by estrus suppression for 4 months	22
9 females	18 mg (single implant)	During estrus	Within 9–11 days of implant insertion, 78% had superficial cells present on vaginal cytology and estrous behavior for 2–3 days followed by estrus suppression for 2 months	22
12 females	4 mg/cat q24h PO until onset of estrus	During interestrus	Prolonged interestrus (interval between onset of treatment and first estrous cycle was 50 ± 6.1 days)	23
17 females	18 mg (single implant)	During interestrus	Prolonged interestrus (interval between onset of treatment and first estrous cycle was 51 ± 4.7 days)	23
4 males	18 mg (single implant)	Not applicable	100% significantly decreased their sperm quality until 120 ± 15 days after implant insertion	24
12 females	18 mg (single implant)	Prepubertally	Did not delay puberty	23
10 females	4 mg/cat q24h PO until onset of estrus	Prepubertally	Did not delay puberty	23

SC = subcutaneous, PO = oral