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pros-tuh-GLAN-din - Pronunciation guide

Brand Names

  • Lutalyse Sterile Solution
  • ProstaMate
  • Estromil


Rx symbolProstaglandin is naturally produced in the horse's body. Chemically, it is any of a class of unsaturated fatty acids that are involved in the contraction of smooth muscle, the control of inflammation and body temperature, and many other physiological functions in the body. Synthetic prostaglandin is used in several ways to help control reproduction in mares by manipulation of the estrous cycle and in the termination of pregnancy.


Prostaglandin is used in what is often referred to as "short cycling." After ovulation occurs in the mare, if the mare does not become pregnant when bred, the mare's uterus normally produces enough prostaglandin to terminate the corpus luteum and the mare returns to heat. In some cases, use of synthetic prostaglandin is considered necessary to shorten the cycle so the mare returns to heat sooner. Synthetic prostaglandin may also be used to terminate an early pregnancy.

Prostaglandin is also used in the treatment of uterine infections, such as endometritis and pyometra, which are easier to diagnose and treat during estrus.

Dosage and Administration

Prescription medicationProstaglandin
Method Dosage
(click row for calculator)
Concentration Period Duration
Controlling Time of Estrus of Estrous Cycling Mares
Intramuscular injection1 .01 mg/lb 5 mg/ml Single injection NA


  • 1Mares:
    1. Evaluate the reproductive status of the mare.
    2. Administer a single intramuscular injection of 1 mg per 100 lbs (45.5 kg) body weight which is usually 1 mL to 2 mL LUTALYSE Sterile Solution.
    3. Observe for signs of estrus by means of daily teasing with a stallion, and evaluate follicular changes on the ovary by palpation of the ovary per rectum.Some clinically anestrous mares will not express estrus but will develop a follicle which will ovulate. These mares may become pregnant if inseminated at the appropriate time relative to rupture of the follicle.
    4. Breed mares in estrus in a manner consistent with normal management.
  • Federal law restricts this drug to use by or on the order of a licensed veterinarian.
  • Extra-label use of drugs in treating animals is allowable only by licensed veterinarians within the context of a valid veterinarian-client-patient relationship, and does not include drug use in treating animals by the layman (except under the supervision of a licensed veterinarian).
  • The duration of administration depends on the condition being treated, response to the medication and the development of any adverse effects. Be certain to complete the prescription unless specifically directed by your veterinarian. Even if your equine appears to feel better, the entire treatment plan should be completed to prevent relapse.
  • This medication may be available in forms and concentrations not noted in the above table. Always check the label and literature provided with the medication about the form and concentration and DO NOT USE the calculator if the information differs.
  • Calculator is for educational purposes only. Follow your veterinarian's instructions regarding use of this, or any medication.

Side Effects

Side effects are common, but not usually life-threatening and often diminish within an hour. Common side effects are restlessness, cramping, colic-like pain, panting, sweating, high heart rate, diarrhea, urination, and defecation.

Mares that have been given high levels of anabolic steroids and other hormones may not respond to prostaglandin until their bodies are no longer under the effects of these drugs.


Precautions for humans: Pregnant women, asthmatics, and persons with bronchial disease should not handle this product. If skin is accidentally exposed, the area should be washed immediately.

Prostaglandin is for intramuscular injection only and should not be injected intravenously.

Prostaglandin F2 alpha is FDA approved for use with horses and is a prescription drug restricted to use by or on the lawful written or oral order of a licensed veterinarian.

Prostaglandin is not commonly used in competition horses and would be forbidden in drug-free competition. It is important to check with the individual regulatory group.


Prostaglandins may enhance the activity of other drugs that affect the uterus, such as oxytocin.


Symptoms of overdose are the same as side effects, but more severe.


Estromil Prostaglandin InjectionEstromil Prostaglandin Injection

Lutalyze InjectionLutalyze Injection



About the Author

EquiMed Staff

EquiMed staff writers team up to provide articles that require periodic updates based on evolving methods of equine healthcare. Compendia articles, core healthcare topics and more are written and updated as a group effort. Our review process includes an important veterinarian review, helping to assure the content is consistent with the latest understanding from a medical professional.