Dinoprost
Dinoprost tromethamine is a synthetic analogue of **Prostaglandin F2 alpha (PGF2α)**. In veterinary medicine, it is primarily used for its ecbolic effects to stimulate **uterine contractions** and induce **cervical relaxation**, making it a key medical treatment for **open pyometra**. > **WARNING:** Pregnant women and asthmatics should strictly avoid handling this medication due to the risk of inducing bronchospasm or miscarriage. **Clinical Pearl:** While the primary indication listed for small animals is open pyometra, PGF2α is also widely used for luteolysis (corpus luteum regression) in large animals and occasionally for pregnancy termination in small animals.
Mechanism: Dinoprost acts directly on the myometrium and corpus luteum. * Binds to specific **FP receptors** on smooth muscle cells. * → Increases intracellular calcium concentrations. * → Induces strong, rhythmic **uterine contractions**. * → Concurrently causes **cervical relaxation** to allow expulsion of uterine contents. * → Induces luteolysis (regression of the corpus luteum), leading to a rapid drop in progesterone levels.
Dosing by species
- Open pyometra / Uterine contraction · 0.1 or 0.25 mg/kg · SC · q12-24h
- Open pyometra · 0.1-0.25 mg/kg · SC · q12h · until the uterus is empty; usually 3-5 days treatment required
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Closed pyometra (due to severe risk of uterine rupture)
- Pregnancy (unless abortion is the intended outcome)
- Patients with respiratory disease/asthma (due to bronchoconstriction risk)
Adverse effects
- Hypersalivation (drooling)
- Panting
- Tachycardia
- Vomiting
- Urination
- Defecation
- Transient hyperthermia
- Locomotor incoordination
- Mild CNS signs
Monitoring
- Resolution of pyometra (via ultrasound and monitoring of vaginal discharge)
- Heart rate and respiratory rate post-injection
- Signs of excessive distress or hyperthermia
Overdose
Overdosage can lead to an exaggeration of the expected side effects, including severe vomiting, diarrhea, profound tachycardia, hyperthermia, and severe panting. In cases of closed pyometra, excessive doses or any use can cause **uterine rupture** and subsequent fatal peritonitis. Treatment is largely supportive as the drug has a very short half-life.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.