💊 Vet’s 2025 Guide to Domperidone (Equidone® Gel) in Horses

By Dr Duncan Houston BVSc

1. What Is Domperidone?

Domperidone is a **D₂ dopamine receptor antagonist** available in oral gel form under the FDA-approved brand **Equidone® Gel** for horses. Its primary indication is prevention of **fescue toxicosis** in pregnant mares grazing endophyte-infected tall fescue. It’s also used off-label for diagnosing **pituitary pars intermedia dysfunction (PPID)**. :contentReference[oaicite:3]{index=3}

2. How It Works

• Blocks excessive dopamine signalling at the pituitary, restoring prolactin release—critical for lactation and fetal development in late pregnancy. :contentReference[oaicite:4]{index=4}
• May increase gut motility due to peripheral D₂ blockade—caution in GI disease. :contentReference[oaicite:5]{index=5}

3. Approved Use: Fescue Toxicosis Prevention

Grazing **endophyte-infected fescue** during late pregnancy can lead to prolonged gestation, dystocia, agalactia, stillbirth, or thickened placenta. Domperidone given orally beginning **10–15 days before** the expected foaling date, daily up to 5 days postpartum, significantly reduces these risks—vitally improving foal health outcomes. :contentReference[oaicite:6]{index=6}

4. Off-Label Use: PPID Diagnosis Support

Domperidone may help in diagnosing PPID by evaluating prolactin response, though this is off-label and should be undertaken under veterinary guidance. :contentReference[oaicite:7]{index=7}

5. Dosing Guidelines

6. Timing and Safety Considerations

• **Do not start earlier than 15 days before expected foaling** to avoid premature parturition, low birth weight, or foal morbidity. :contentReference[oaicite:9]{index=9}
• Domperidone may **interfere with milk calcium tests**, causing false predictions of imminent foaling. :contentReference[oaicite:10]{index=10}
• Handle gel with care—human exposure may disrupt hormonal balance; pregnant/lactating women should wear gloves. :contentReference[oaicite:11]{index=11}

7. Side Effects & Monitoring

• **Premature lactation** (milk dripping pre-foaling): seen in ~1–10% of treated mares. :contentReference[oaicite:12]{index=12}
• **Failure of passive transfer (FPT)** in foals due to early milk loss—monitor IgG levels in all foals. :contentReference[oaicite:13]{index=13}
• MIld GI signs possible; contraindicated in GI obstruction, bleeding, or perforation. :contentReference[oaicite:14]{index=14}
• Domperidone is a **P-gp substrate metabolized by CYP3A4**; interactions with ketoconazole or erythromycin may raise domperidone levels—monitor for signs of overdose. :contentReference[oaicite:15]{index=15}

8. Storage and Administration

• Comes in a 25 mL multi-dose syringe (110 mg/mL; 2.75 g total) with dosing dial. :contentReference[oaicite:16]{index=16}
• Store at controlled room temperature (59–86 °F). :contentReference[oaicite:17]{index=17}
• Ensure mare’s mouth is empty at administration; clean syringe between doses. :contentReference[oaicite:18]{index=18}

9. Efficacy Evidence

Field trials have shown **92% success** in preventing prolonged gestation and agalactia versus 7% in untreated controls. Foals from treated mares showed healthier delivery and better milk transfer. :contentReference[oaicite:19]{index=19}

10. Contraindications & Warnings

• Avoid in mares with known domperidone allergy or GI disease. :contentReference[oaicite:20]{index=20}
• Not for use in horses intended for human consumption—no withdrawal time defined. :contentReference[oaicite:21]{index=21}
• Not evaluated in stallions, young foals, or outside peri‑partum window. :contentReference[oaicite:22]{index=22}

11. Ask A Vet Support 🩺

At Ask A Vet, we help you:

• Calculate accurate dosing for your mare
• Determine correct start timing and monitor foal IgG
• Assess PPID diagnostics when suspected
• Evaluate potential drug interactions
• Respond to side effects like premature lactation or GI upset

Use our app for dosing reminders, telehealth having emergency concerns, and personalized support before, during, and after foaling.

12. Quick Reference Table

13. FAQs

❓ Can Domperidone induce labor?

Yes, if started earlier than 15 days before expected foaling, it may cause premature parturition and low foal weight. :contentReference[oaicite:23]{index=23}

❓ Should my foal have an IgG test?

Yes—all foals from treated mares need serum IgG testing to check passive immunity. :contentReference[oaicite:24]{index=24}

❓ Can domperidone be used long‑term postpartum?

Limited data support extended use beyond five days post-foaling. Extended use is off-label and should be vet-guided. :contentReference[oaicite:25]{index=25}

14. Final Thoughts

Domperidone (Equidone® Gel) remains a cornerstone therapy to prevent life-threatening effects of fescue toxicosis. With correct timing, dosing, and monitoring, mares and foals stay healthier. Off-label use for PPID diagnostics can be helpful under vet guidance. For expert support—dosing setup, side‑effect monitoring, drug interactions, and foal health—partner with Ask A Vet. Download our app today to ensure safe, informed care in 2025! ❤️