Cloprostenol Sodium
Cloprostenol sodium is a synthetic **prostaglandin F2ฮฑ (PGF2ฮฑ) analogue** widely used in veterinary medicine primarily for its potent **luteolytic** properties. It is structurally related to naturally occurring dinoprost but is significantly more potent and has a longer duration of action. * **Large Animals:** It is a staple in bovine, equine, and swine reproduction for estrus synchronization, inducing parturition, and managing reproductive pathologies such as luteal cysts, mummified fetuses, or chronic endometritis. * **Small Animals:** In dogs, it is used off-label for pregnancy termination and the medical management of open-cervix pyometra. **Clinical Pearl:** Because it is a synthetic analogue, cloprostenol often exhibits fewer systemic side effects in horses compared to natural PGF2ฮฑ (dinoprost), though dogs may still experience significant cholinergic-like adverse effects (which can be mitigated by pre-treatment with anticholinergics like atropine).
Mechanism: Cloprostenol acts as a potent agonist at **prostaglandin F (FP) receptors**. * **Luteolysis:** Binds to FP receptors on the **corpus luteum (CL)** โ induces rapid functional and structural regression (luteolysis) โ sharp decline in **progesterone** production. This drop in progesterone removes the negative feedback on the hypothalamus/pituitary, allowing a return to estrus, or induces abortion/parturition depending on the stage of gestation. * **Myometrial Contraction:** Directly stimulates FP receptors on **uterine smooth muscle** โ increases intracellular calcium โ powerful, rhythmic uterine contractions (ecbolic effect). * **Cervical Relaxation:** Concurrently promotes relaxation and dilation of the cervix, facilitating the expulsion of uterine contents (e.g., fetus, purulent material in pyometra).
Dosing by species
- To induce parturition in does ยท 62.5-125 micrograms ยท IM ยท once ยท Give at 144 days of gestation in early morning. Deliveries will peak at 30-35 hours after injection. Maintain goat in usual surroundings and minimize outside disturbances.
- To treat pseudopregnancy (hydrometra/mucometra) ยท 125 micrograms ยท IM ยท once
- For treatment of pyometra ยท 500 micrograms ยท IM ยท once ยท Up to 97% efficacy.
- For pyometra or chronic endometritis, mummified fetus, luteal cysts ยท 500 micrograms ยท IM ยท once ยท Manual assistance may be required to remove mummified fetus from vagina.
- For unobserved or undetected estrus in cows with continued ovarian cyclicity and a mature corpus luteum ยท 500 micrograms ยท IM ยท once ยท Estrus should commence in 2-5 days at which time the animal may be inseminated. If estrus detection is not possible, inseminate twice at 72 and 96 hours post injection.
- For abortion, from one week after mating to approximately the 150th day of gestation ยท 500 micrograms ยท IM ยท once ยท Abortion generally takes place in 4-5 days after injection.
- For controlled breeding (Single injection method) ยท 500 micrograms ยท IM ยท once ยท Use only animals with mature corpus luteum. Inseminate at usual time after detecting estrus, or once at 72 hours, or twice at 72 and 96 hours post injection.
- For controlled breeding (Double injection method) ยท 500 micrograms ยท IM ยท Repeat dose 11 days later ยท Estrus should occur in 2-5 days after second injection.
Routes of administration
Contraindications
- Pregnancy (when abortion or induced parturition are not desired)
- Intravenous (IV) administration
Adverse effects
- Increased salivation (dogs)
- Tachycardia (dogs)
- Increased urination and defecation (dogs)
- Gagging and vomiting (dogs)
- Ataxia and mild depression (dogs)
- Sweating (horses)
- Cramping and loose stools (horses)
- Increased risk of dystocia if used after 5th month of gestation (cattle)
Drug interactions
- Oxytocic agents ยท Activity may be enhanced by cloprostenol
Monitoring
- Resolution of clinical signs (e.g., clearance of pyometra)
- Estrus behavior and timing
- Confirmation of pregnancy termination/abortion
- Adverse cholinergic effects in dogs (salivation, vomiting, heart rate)
Overdose
In **cattle**, doses of 50 and 100 times those recommended may cause signs of uneasiness, slight frothing, and milk let-down. In **small animals**, overdoses of cloprostenol or other synthetic prostaglandin F2ฮฑ analogs reportedly can result in severe shock and death.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.