Prostaglandin F2 Alpha

Prostaglandin F2alpha, supplied pharmacologically as dinoprost, is a naturally occurring luteolytic prostaglandin used in veterinary reproduction. Its clinical roles include control of the estrous cycle, selected pregnancy-termination protocols and uterine evacuation. It is distinct from synthetic analogues such as cloprostenol, although they share important receptor-mediated effects.

Group

Luteolytic prostaglandin

Mechanism of Action

Prostaglandin F2alpha activates FP receptors in responsive luteal tissue, promoting functional and structural regression of the corpus luteum and a fall in progesterone secretion. This can permit return to estrus or terminate a progesterone-dependent pregnancy. Receptor activation also increases uterine smooth-muscle contraction, contributing to evacuation of uterine contents and selected parturition-induction effects.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Open pyometra	0.1–0.2 mg/kg	SC	Every 24 h	Up to 5 days; Do not use in: Pregnancy unless termination intended
Pregnancy termination	0.1–0.25 mg/kg	SC	Every 8–12 h	Do not use in: Pregnancy unless termination intended
Pregnancy termination staged protocol — Initial	0.1 mg/kg	SC	Every 8 h	Up to 2 days; Do not use in: Pregnancy unless termination intended
Pregnancy termination staged protocol — Maintenance	0.2 mg/kg	SC	Every 8 h	Up to 9 days; Do not use in: Pregnancy unless termination intended; After first 2 days, continue until abortion complete, usually within 9 days; not a guaranteed fixed-length course.
Pyometra staged protocol — Initial	0.1 mg/kg	SC	Once	Select stable breeding candidates with an open cervix; concurrent antibiotics.
Pyometra staged protocol — Maintenance	0.2 mg/kg	SC	Once	Day 2 only.
Pyometra staged protocol — Maintenance	0.25 mg/kg	SC	Every 24 h	Up to 5 days; Days 3-7; reassess uterus at 7 and 14 days.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Open pyometra	0.1–0.25 mg/kg	SC	Every 24 h	Up to 5 days; Do not use in: Pregnancy unless termination intended
Pregnancy termination injections	Reference only	IM		Do not use in: Pregnancy unless termination intended; 0.5-1 mg/kg IM for two injections; the interval is unspecified.
Pregnancy termination staged protocol — Initial	0.2 mg/kg	SC	Every 12 h	Up to 1 days; Do not use in: Pregnancy unless termination intended
Pregnancy termination staged protocol — Maintenance	0.5 mg/kg	SC	Every 12 h	Up to 5 days; Do not use in: Pregnancy unless termination intended
Pyometra staged protocol — Initial	0.1 mg/kg	SC	Once	Select stable breeding candidates with an open cervix; concurrent antibiotics.
Pyometra staged protocol — Maintenance	0.25 mg/kg	SC	Every 24 h	Up to 5 days; After initial 0.1 mg/kg; avoid severely ill cats and assess age/closed-cervix risk.
Pregnancy termination	2 mg/animal	IM	Every 24 h	Begun at gestation day 33 in reported protocol.

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Pregnancy termination	25 mg/animal	IM	Once	Do not use in: Pregnancy unless termination intended
Pyometra	25 mg/animal	IM	Once	Do not use in: Pregnancy unless termination intended
Estrus synchronization	25 mg/animal	IM	Once	Do not use in: Pregnancy unless termination intended; One dose, or two doses 10-12 days apart.
Pyometra	25 mg/animal	IM	Every 8 h	Two injections; reassess uterus before breeding.
Pregnancy termination	25–30 mg/animal	IM	Once	Reported gestation days 5-150; after 150 days, a separate dexamethasone combination is described.
Parturition induction	25–30 mg/animal	IM	Once	Delivery may occur about 72 hours later.

Horses

Use / stage	Dose	Route	Schedule	Instructions
Estrus synchronization	0.0222222222 mg/kg	IM	Once	Do not use in: Pregnancy unless termination intended; Exact reported proportion 1 mg per 45 kg. Expected estrus 2-4 days and ovulation 8-12 days later.
Estrus synchronization	5–10 mg/animal	IM	Once	Do not use in: Pregnancy unless termination intended; Alternative 1-2 mL of 5 mg/mL dinoprost.
Luteolysis and uterine contraction	10 mg/animal	IM	Once
Early pregnancy termination	5 mg/animal	IM	Once	Before pregnancy day 12.

Pigs

Use / stage	Dose	Route	Schedule	Instructions
Parturition induction	10 mg/animal	IM	Once	Do not use in: Pregnancy unless termination intended; Within 3 days of expected farrowing; delivery is described within 30 hours.
Pregnancy termination	5–10 mg/animal	IM	Once
Parturition induction	10–25 mg/animal	IM	Once	Reported 2-6 days before expected farrowing; delivery often 24-36 hours later.

Sheep

Use / stage	Dose	Route	Schedule	Instructions
Estrus synchronization	8 mg/animal	IM	Once	Ewes on cycle day 5, does on day 4; repeat after 11 days.
Pregnancy termination	10–15 mg/animal	IM	Once	First two months of pregnancy.

Goats

Use / stage	Dose	Route	Schedule	Instructions
Estrus synchronization	8 mg/animal	IM	Once	Ewes on cycle day 5, does on day 4; repeat after 11 days.
Pseudopregnancy	5 mg/animal	IM	Once
Pregnancy termination	5–10 mg/animal	IM	Once

Indications

Estrus synchronization or induction of luteolysis in cattle and mares with a responsive corpus luteum.
Treatment of selected bovine pyometra or chronic endometritis associated with persistent luteal activity.
Specialist medical treatment of selected open-cervix pyometra in dogs.
Selected pregnancy-termination or mummified-fetus-expulsion protocols in veterinary reproduction.
Induction of farrowing in pigs near the expected parturition date.

Contraindications

Never IV.
Pregnancy unless termination is intended.
Pregnant or respiratory-sensitive handlers should avoid exposure and skin contact.

Interactions

Oxytocin can increase uterine-rupture risk; reported label cautions against NSAID coadministration.

Adverse effects

Vomiting, diarrhea, abdominal discomfort, bronchoconstriction, blood-pressure increase and retained placenta.

Toxicity

Excess dinoprost produces pronounced smooth-muscle and autonomic effects; dogs may be particularly sensitive. Support respiratory and cardiovascular function and assess reproductive complications.

Preparations

Preparation	Form	Strength	Route
Dinoprost injection 5 mg/mL	Injection	5 mg / mL	IM, SC

Monitoring and Administration

Confirm reproductive stage and follow uterine response and estrus. Monitor pyometra treatment closely; dinoprost and more potent synthetic analogs are not dose-interchangeable.

Canine abortion alternatives after day 25-30 use 80-100 mcg/kg SC at least twice daily, beginning at half dose for the first two administrations, continuing until confirmed completion. Midterm combination uses vaginal misoprostol 1-3 mcg/kg daily plus dinoprost 0.1 mg/kg SC three times daily for 3 days then 0.2 mg/kg to effect. Bovine late-gestation combination uses dexamethasone 25 mg with dinoprost 25 mg IM. Porcine grouping protocol uses 15 mg IM then 10 mg 12 hours later; do not average these staged amounts.