Dinoprost

Dinoprost is naturally occurring prostaglandin F2alpha supplied in veterinary products, commonly as the tromethamine salt. It is used for luteolysis, control of the estrous cycle and selected reproductive disorders in cattle, horses and pigs. Its uterine smooth-muscle effects also contribute to specialist medical treatment of selected reproductive conditions in small animals.

Group

Prostaglandin F2-alpha

Mechanism of Action

Dinoprost activates prostaglandin F receptors in luteal tissue and uterine smooth muscle. In a responsive corpus luteum, it causes functional and structural regression with a decline in progesterone secretion. This can permit return to estrus or termination of a progesterone-dependent pregnancy. Direct stimulation of uterine contractions supports evacuation of uterine contents and contributes to parturition-induction protocols.

Dose Rates

Dog

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: IV administration
Pregnancy termination	0.025–0.05 mg/kg	IM	Every 12 h	Do not use in: IV administration

Cat

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: IV administration
Pregnancy termination	0.5–1 mg/kg	IM		Do not use in: IV administration; Two injections; the source does not specify their interval.
Pregnancy termination	2 mg	IM	Every 24 h	Begin on gestation day 33; monitor vomiting, diarrhea and marked weakness.

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Pregnancy termination	25 mg/animal	IM	Once	Do not use in: IV administration; For pregnancy termination, source limits use to the first 100 days of gestation.
Pyometra	25 mg/animal	IM	Once	Do not use in: IV administration
Estrus synchronization	25 mg/animal	IM	Once	Do not use in: IV administration; One injection, or a second injection after 10–12 days. Breed relative to estrus; timed breeding around 80 hours after the second injection is described.
Pyometra repeated-dose protocol	Reference only	IM		25 mg twice, eight hours apart. Assess uterine evacuation by palpation or ultrasonography before breeding.

Horse

Use / stage	Dose	Route	Schedule	Instructions
Estrus synchronization	5–10 mg/animal	IM	Once	Do not use in: IV administration; Equivalent to 1–2 mL of 5 mg/mL injection. Alternative source amount: 1 mg per 45 kg; return to estrus commonly 2–4 days.

Pig

Use / stage	Dose	Route	Schedule	Instructions
Induction of parturition	10 mg/animal	IM	Once	Do not use in: IV administration; Within 3 days of predicted farrowing; onset commonly around 30 hours.
Estrus grouping	Reference only	IM		At 15–55 days gestation give 15 mg, followed 12 hours later by 10 mg. This induces abortion; estrus generally returns 4–5 days later.

Goat

Use / stage	Dose	Route	Schedule	Instructions
Pseudopregnancy	5 mg	IM	Once
Pregnancy termination	5–10 mg	IM		Reported throughout pregnancy; abortion may occur in 4–5 days.
Estrus synchronization	Reference only	IM		Cycling animals: 8 mg on estrous-cycle day 4, repeated 11 days later. Estrus is expected about two days after the second injection.

Sheep

Use / stage	Dose	Route	Schedule	Instructions
Pregnancy termination	10–15 mg	IM		Restricted to the first two months of pregnancy in this regimen; effect may take 72 hours.
Estrus synchronization	Reference only	IM		Cycling animals: 8 mg on estrous-cycle day 5, repeated 11 days later. Estrus is expected about two days after the second injection.

Indications

Estrus synchronization and induction of luteolysis in cattle and mares with a responsive corpus luteum.
Treatment of bovine pyometra, selected chronic endometritis or luteal cysts associated with persistent luteal activity.
Induction of parturition in pigs near the expected farrowing date.
Pregnancy termination or expulsion of a mummified fetus in cattle within an appropriate reproductive protocol.
Specialist medical treatment of selected canine open-cervix pyometra.
Selected pregnancy-termination protocols in small animals, generally within a supervised combination reproductive regimen.

Contraindications

Never IV
Pregnancy unless termination/parturition is intended
Closed-cervix pyometra without an appropriate treatment plan

Interactions

Oxytocin increases uterine stimulation and rupture risk.

Adverse effects

Vomiting, diarrhea, abdominal discomfort
Bronchoconstriction
Retained placenta after pregnancy termination

Preparations

Preparation	Form	Strength	Route
Dinoprost injection 5 mg/mL SC small-animal use is extralabel; never IV.	Injection	5 mg / mL	IM, SC

Monitoring and Administration

Pregnant people and people with respiratory disease must avoid handling; skin absorption is possible.

Confirm a responsive corpus luteum where required. Monitor estrus, uterine evacuation and systemic response.