Equine · Equus caballus · typical adult weight 350.00–700.00 kg
Erythromycin is dosed at 25–37.5 mg/kg PO q8-12h in horses, per Plumb's Veterinary Drug Handbook — Plumb's 10th ed (held) printed p.473, Erythromycin monograph spanning p.473-476; page located 2026-08-05 from the book's own running heads, verified to name the drug in its body text. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207. Erythromycin is used in horses for Rhodococcus equi in foals (with rifampin), Rhodococcus equi pneumonia (foals). Routes documented in horses: PO. A typical adult horse weighs 350.00–700.00 kg. ExoticRx lists 2 cited dose rules for Erythromycin in horses, drawn from published veterinary references. Verify against current literature before clinical use.
US trade names: Erythro-100, Gallimycin
Contraindicated in Chinchilla, Guinea Pig, Rabbit, Hamster, Degu
| Route | Dose | Frequency | Duration | Indication | Evidence | Source |
|---|---|---|---|---|---|---|
| PO | 25–37.5 mg/kg | q8-12h | 4-12 weeks | Rhodococcus equi in foals (with rifampin) | Strong | Plumb's Veterinary Drug Handbook — Plumb's 10th ed (held) printed p.473, Erythromycin monograph spanning p.473-476; page located 2026-08-05 from the book's own running heads, verified to name the drug in its body text. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 |
| PO | 25 mg/kg | q6-8h | 4-9 weeks | Rhodococcus equi pneumonia (foals) | Strong | Lavoie J-P, Drolet R. Proliferative enteropathy in foals. 2003 PMID: 35074397 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.503 (2026-08-01). — Plumb's 10th ed (held) printed p.476, Erythromycin monograph spanning p.473-476; page located 2026-08-05 from the book's own running heads, and carries this exact dose under the matching species heading. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, | ORIGINAL SOURCE THE BOOK CITES (2026-08-20): the dose row carries superscript 17 — "25 mg/kg PO once daily17 Chemistry/Synony" — which resolves in the monograph's own reference list to: Albarellos GA, Montoya L, Landoni MF. Pharmacokinetics of erythromycin after intravenous, intramuscular and oral administration to cats. Veterinary Journal. 2011;187(1):129-132. This records what the handbook attributes the figure to. It is NOT a statement that the reference was read or that it validates the dose. |
Every held source for this drug and species, as printed. Where they differ, both are shown — the choice is yours, not ours.
| Dose (mg/kg) | Route | Source | As printed |
|---|---|---|---|
| 37.5 | PO | Papich Saunders Handbook of Veterinary Drugs, 4th edp.327 | • R. equi: Erythromycin phosphate or erythromycin estolate 37.5 mg/kg q12h PO |
| 25 | PO | Papich Saunders Handbook of Veterinary Drugs, 4th edp.327 | or 25 mg/kg q8h PO. Note that in horses, erythromycin base (plain tablets) are |
| 5 | IV | Papich Saunders Handbook of Veterinary Drugs, 4th edp.327 | • Erythromycin lactiobionate injection: 5 mg/kg q4-6h IV. To stimulate GI motility: |
| 1 | — | Papich Saunders Handbook of Veterinary Drugs, 4th edp.327 | 1 mg/kg. |
Figures are transcribed from the cited page or table of each held edition and are shown for reference only. They are not dose recommendations, they do not feed the calculator, and none has been reviewed by a veterinarian.
Need the exact dose for your patient?
These ranges are per kg. Enter your horse's weight to get the precise dose and draw-up volume — unit and concentration math done for you.
Binds 50S ribosomal subunit, inhibiting translocation of peptidyl-tRNA, blocking bacterial protein synthesis.
CONTRAINDICATED in rabbits and hindgut fermenters. Prokinetic at sub-antimicrobial doses. GI upset common. Hepatotoxicity reported. Strong CYP inhibitor.
Species-specific contraindications and adverse-reaction reports for horses may differ from canine / feline reference data — consult the primary citations listed with each rule.
Erythromycin dose ranges in horses, with cited source references: PO 25–37.5 mg/kg q8-12h; PO 25 mg/kg q6-8h. Reference ranges from cited sources — verify against current literature before clinical use.
Documented routes for Erythromycin in horses: PO.
Cited course lengths for Erythromycin in horses include: 4-12 weeks; 4-9 weeks. Duration depends on the indication — match it to the specific dose rule in the table above.
Erythromycin is indicated in horses for: Rhodococcus equi in foals (with rifampin), Rhodococcus equi pneumonia (foals).
These are general warnings for Erythromycin across species; consult the horse dosing table above for species-specific guidance. CONTRAINDICATED in rabbits and hindgut fermenters. Prokinetic at sub-antimicrobial doses. GI upset common. Hepatotoxicity reported. Strong CYP inhibitor.
Why a species-specific page? Erythromycin pharmacokinetics differ across species: dose ranges, intervals, and route preferences are not interchangeable. Cross-extrapolation from canine doses is unsafe in horses — the rules above are the citations specific to this species, not generic recommendations.
Sourced from published veterinary references; awaiting credentialed clinical reviewer. See our editorial process. Reference only — not veterinary advice.