Cloprostenol

Cloprostenol is a synthetic prostaglandin F2alpha analogue used principally for luteolysis and reproductive management. In cattle, it is used to control the estrous cycle and treat selected disorders associated with a functional corpus luteum. Additional veterinary applications include reproductive protocols in mares and specialist medical management of selected reproductive conditions in small animals.

Group

Prostaglandin F2alpha analogue

Mechanism of Action

Cloprostenol activates prostaglandin F receptors in luteal tissue, initiating functional and structural regression of a responsive corpus luteum. The resulting decline in progesterone removes luteal suppression of the reproductive cycle and can permit return to estrus or termination of a progesterone-dependent pregnancy. It also stimulates uterine smooth-muscle contraction, supporting evacuation of uterine contents in selected reproductive disorders.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Pregnancy termination	1–2.5 mcg/kg	SC	Every 24 h	Up to 5 days; Begin around day 25 after mating; course 4–5 days. Adverse effects are lower at 1 mcg/kg.
Pregnancy termination with cabergoline	Reference only	SC		35–45 days after mating: cloprostenol 1 mcg/kg SC on days 1 and 3 plus cabergoline 5 mcg/kg orally daily on days 1–7. Preserve the complete combination schedule.
Pregnancy termination with bromocriptine	Reference only	SC		Cloprostenol 1 mcg/kg SC every 48 hours with the staged bromocriptine regimen; see Monitoring and Administration.
Open-cervix pyometra adjunct	Reference only	PO		1–5 mcg/kg once daily for up to 2–3 weeks, starting at half dose and increasing over 2–3 days; route is not specified. Do not infer a complete medical-pyometra protocol from this bullet.
Pyometra combination treatment	Reference only	SC		Cloprostenol 1 mcg/kg SC every five days for up to 15 days, with aglepristone 10 mg/kg SC every five days until resolved, appropriate antibacterial therapy and hydration. Use only a selected medical-management plan with reassessment.
Pregnancy termination	1–2.5 mcg/kg	SC	Every 24 h	Up to 7 days; Historical course 4–7 days after approximately day 30 of gestation; confirm completion.
Alternate-day pregnancy termination	1–2.5 mcg/kg	SC	Every 48 h	Three doses total. The supplemental parenthesis says mg/kg but conflicts with the same bullet’s mcg/kg regimen; the thousand-fold unit error is not used.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Pregnancy termination	5 mcg/kg	SC	Every 24 h	Up to 3 days

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Luteolysis and estrus synchronization	500 mcg/animal	IM	Once	May repeat 11 days later; estrus generally follows within 2–5 days after the effective injection.
Pyometra or chronic endometritis	500 mcg/animal	IM	Once	For pregnancy termination the described period is one week after mating to about day 150. A mummified fetus may need assistance for removal.
Luteal cyst or mummified fetus	500 mcg/animal	IM	Once	For pregnancy termination the described period is one week after mating to about day 150. A mummified fetus may need assistance for removal.
Pregnancy termination	500 mcg/animal	IM	Once	For pregnancy termination the described period is one week after mating to about day 150. A mummified fetus may need assistance for removal.

Horses

Use / stage	Dose	Route	Schedule	Instructions
Pregnancy termination	500 mcg/animal	IM		Repeat injections at 12-hour intervals have been used in selected circumstances.
Endometritis	250 mcg/animal	IM	Every 12 h	Up to 1 days; Two injections 12 hours apart; usually combined with oxytocin.
Early pregnancy termination	100 mcg/animal	IM	Once	Before day 12 of gestation, with greatest described effect around day 7–8 after estrus.
Luteolysis	25–250 mcg/animal	IM	Once
Uterine evacuation	250 mcg/animal	IM	Every 24 h	Avoid use more than one day after ovulation when preservation of luteal function is desired.

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Parturition induction	175 mcg/animal	IM	Once	Sows only, no earlier than two days before expected farrowing; parturition generally follows around 36 hours later.

Goats

Use / stage	Dose	Route	Schedule	Instructions
Parturition induction	62.5–125 mcg/animal	IM	Once	Does around gestation day 144; deliveries commonly peak 30–35 hours afterward. Keep surroundings quiet.
Hydrometra or pseudopregnancy	125 mcg/animal	IM	Once

Alpacas

Use / stage	Dose	Route	Schedule	Instructions
Luteolysis	100 mcg/animal	IM	Once	Historical restriction: not more than four days after ovulation; pregnancy loss is possible.

Llamas

Use / stage	Dose	Route	Schedule	Instructions
Luteolysis	250 mcg/animal	IM	Once	Historical restriction: not more than four days after ovulation; pregnancy loss is possible.

Indications

Estrus synchronization and induction of luteolysis in cycling cattle with a responsive corpus luteum.
Treatment of luteal cysts or persistent luteal activity in cattle.
Treatment of bovine pyometra or selected chronic endometritis associated with a functional corpus luteum.
Induction of pregnancy termination or expulsion of a mummified fetus in cattle within an appropriate reproductive protocol.
Induction of luteolysis, cycle control or selected pregnancy-termination protocols in mares.
Specialist medical treatment of selected canine open-cervix pyometra or pregnancy termination, generally within a combination reproductive protocol.

Contraindications

Pregnancy when continued gestation is intended.
Handle with particular care around people with asthma or who may be pregnant.
Do not administer intravenously.

Interactions

Combination protocols with dopamine agonists or gonadorelin require their full schedules.
Other uterotonics, including oxytocin, can have enhanced effects.

Adverse effects

Abortion
Vomiting, panting, nausea or diarrhea
Vulvar discharge
Transient mammary enlargement
Endometritis after some treatments

Preparations

Preparation	Form	Strength	Route
Cloprostenol injection 250 mcg/mL Cloprostenol active-equivalent strength; dilute carefully for small-animal use. Do not confuse with more potent dexcloprostenol products.	Injection	250 mcg / mL	IM, SC

Monitoring and Administration

Monitor reproductive response, persistent discharge and progesterone when indicated. Human skin exposure can cause bronchospasm or abortion; wash splashes immediately and avoid direct handling exposure.

Dogs are commonly treated at least 8 hours after food to limit vomiting. Dilute accurately for small animals.

Canine combination after 35–45 days post-mating: cloprostenol 1 mcg/kg SC on treatment days 1 and 3, after tenfold saline dilution, plus cabergoline 5 mcg/kg orally daily on days 1–7. A separate bromocriptine protocol uses cloprostenol 1 mcg/kg SC every 48 hours with staged oral bromocriptine.

Dairy synchronization protocol: gonadorelin 86 mcg IM on day 0, cloprostenol 500 mcg IM 6–8 days later, another gonadorelin 86 mcg 30–72 hours later, then insemination 8–24 hours afterward.

Equine premature labor in the final 2–4 weeks is described using two doses 30 minutes apart, but the specific dose for that procedure is not independently stated. Do not infer it from pregnancy-termination dosing.

For a cattle single- or double-injection breeding plan, confirm normal cyclicity, a responsive corpus luteum and absence of unintended pregnancy. Estrus generally follows 2–5 days after the effective injection; insemination timing must be matched to the chosen breeding protocol.

The supplemental canine dose parenthesis of 2.5 mg/kg is inconsistent with its 1–2.5 mcg/kg instruction and is not reproduced as a clinical dose.