StallWise / ShowSafe Pro / Withdrawal times / Ace (acepromazine)

Ace (acepromazine) withdrawal and detection times for horses

Ace (acepromazine) is a sedative, also sold as Ace, Promace, Acepromazine Maleate, Sedalin. Below: how 8 show and racing governing bodies list it, every published detection time for the dose and route studied, and the document and page each value comes from.USEF: Permitted with conditionsFEI: Controlled Medication, detection time 72 h (3 days)HISA/HIWU: detection time 48 h (2 days)named in the rules of 20 state racing commissions

Published detection times for Ace

Each row is one study the governing body published: its own dose, route and formulation. A different dose or route was not studied, and the body says so.

Body and documentDose and route studiedFormulationHorsesDetection time
USEF (US Equestrian)
2026 (last revised 1 Dec 2025; amendments effect… p. 11		dose not stated in the row168 h (7 days)
plasma / urine
FEI
2024 (16 December 2024) p. 1		0.15mg/kg, single dose · oralSedalin® (Vetoquinol UK Ltd)672 h (3 days)
Equestrian Canada
Rev. January 15, 2025 p. 18		50mg PO · oral36 h
Equestrian Canada
Rev. January 15, 2025 p. 18		10mg IM · IM36 h
Equestrian Canada
Rev. January 15, 2025 p. 18		25mg IM · IM36 h
Equestrian Canada
Rev. January 15, 2025 p. 18		25mg IV · IV36 h
Equestrian Canada
Rev. January 15, 2025 p. 18		10mg PO · oral24 h (1 day)
HISA / HIWU
Last updated on December 8th, 2023 p. 2		0.15 mg/kg single oral dose · oral672 h (3 days)
plasma / urine
HISA / HIWU
080624 p. 3		0.15 mg/kg single oral dose · oral672 h (3 days)
plasma / urine
HISA / HIWU
Last updated on December 8th, 2023 p. 2		0.05 mg/kg single IV dose · IV2048 h (2 days)
plasma / urine
HISA / HIWU
080624 p. 3		0.05 mg/kg single IV dose (20 horses) · IV2048 h (2 days)
plasma / urine
IFHA / EHSLC
Undated PDF p. 1		0.15mg/kg, single dose · oralSedalin® Vetoquinol UK Ltd672 h (3 days)
urine
RMTC (advisory)
Updated September 30, 2024 p. 2		0.05 mg/kg single IV dose · IV2048 h (2 days)

Advisory withdrawal guidance (RMTC)

The Racing Medication and Testing Consortium publishes withdrawal guidance built on HISA's detection times. It is advisory, not a rule, and ShowSafe Pro shows it beside the HISA result, never in place of it.

Dose and routeWithdrawal guidanceHISA detection timeSource
0.05 mg/kg single IV dose · IV72 h (3 days)RMTC advisory p. 2

How each rulebook lists Ace

Transcribed from the governing bodies' own documents. Each entry links to the document and quotes the row it came from.

USEF (US Equestrian)

2026 USEF Guidelines & Rules for Drugs and Medications (with 27 Jul 2026 Guidelines Update) p. 9 · 2026 (last revised 1 Dec 2025; amendments effective 27 Jul 2026, published 10 Aug 2026)
Permitted with conditions
  • Listed as: Potentially Permitted with Medication Report Form (MRF) according to GR411 · Timing: not within 24 h (1 day) of competition · Medication report form: required
  • Listed as: How Long Drugs Remain Detectable · Detection time: 168 h (7 days) for the dose studied · Medication report form: required
“Potentially Permitted with Medication Report Form (MRF) according to GR411: ... acepromazine” — source p. 9

FEI

2026 Equine Prohibited Substances List p. 1 · 2026 (effective 1 January 2026)
Controlled medication
  • Listed as: Controlled Medication
“CONTROLLED Acepromazine Sedative” — source p. 1
FEI List of Detection Times p. 1 · 2024 (16 December 2024)
Controlled medication
  • Listed as: Controlled Medication · Detection time: 72 h (3 days) for 0.15mg/kg, single dose · Routes: oral
“ACEPROMAZINE2 Sedalin® 0.15mg/kg, single oral 6 72 (3d) Vetoquinol UK Ltd dose” — source p. 1

From 2027-01-01: 2027 Equine Prohibited Substances List p. 1 lists it as Controlled Medication.

Equestrian Canada

Equestrian Canada Equine Medication Control Guide p. 11 · Rev. January 15, 2025
Controlled medication
  • Listed as: Prohibited substance
  • Listed as: Prohibited substance · Detection time: 36 h for 50mg PO · Routes: oral
  • Listed as: Prohibited substance · Detection time: 36 h for 10mg IM · Routes: IM
  • Listed as: Prohibited substance · Detection time: 36 h for 25mg IM · Routes: IM
“Acepromazine” — source p. 11

NRHA

NRHA Medications Database · Database reflecting Board-approved changes effective 1 Jan 2026 (retrieved 3 Oct 2026)
Permitted with conditions
  • Listed as: Conditionally Permitted · Timing: not within 24 h (1 day) of competition · Medication report form: required
“Acepromazine ... Conditionally Permitted ... Conditionally permitted substances require a 24-hour withdrawal prior to the horse competing.” — source

NCHA

2026 NCHA Rule Book - Standing Rule 35A, Medication and Drug Rules and Guidelines p. 13 · 2026 Rule Book, SR 35A extract (pages 75-95; PDF created 30 Jun 2026)
Permitted with conditions
  • Listed as: Conditionally approved medication (35A.8.a, 35A.10.g.i) · Maximum dose: Maximum single dose 5 mg total (.50 mL of 10.0 mg/mL injectable) · Timing: not within 1 h of competition · Medication report form: required
“o. Acepromazine Maleate ... Maximum single dose should not exceed 5 mg total” — source p. 13

HISA / HIWU

Horseracing Integrity & Welfare Unit: Known Detection Times and Screening Limits of Common Controlled Medications p. 3 · 080624
Controlled medication
  • Listed as: Controlled Medication Substance · Screening limit: 10 ng/mL as 2-(1-hydroxyethyl) promazine sulfoxide (HEPS) in urine or 0.02 ng/mL in serum or plasma · Detection time: 72 h (3 days) for 0.15 mg/kg single oral dose · Routes: oral
  • Listed as: Controlled Medication Substance · Screening limit: 10 ng/mL as 2-(1-hydroxyethyl) promazine sulfoxide (HEPS) in urine or 0.02 ng/mL in serum or plasma · Detection time: 48 h (2 days) for 0.05 mg/kg single IV dose (20 horses) · Routes: IV
“Acepromazine ... 1. 0.15 mg/kg single oral dose ... 1. 72 hours (6) ... 10 ng/mL as 2-(1- hydroxyethyl) promazine sulfoxide (HEPS) in urine or 0.02 ng/mL in serum or plasma” — source p. 3
HISA Prohibited Substances List: Controlled Medications p. 2 · Last updated on December 8th, 2023
Controlled medication
  • Listed as: S7 Controlled Medication Substances · Screening limit: 10 ng/mL as 2-(1-hydroxyethyl) promazine sulfoxide (HEPS) in urine; 0.02 ng/mL in serum or plasma · Detection time: 72 h (3 days) for 0.15 mg/kg single oral dose · Routes: oral
  • Listed as: S7 Controlled Medication Substances · Screening limit: 10 ng/mL as 2-(1-hydroxyethyl) promazine sulfoxide (HEPS) in urine; 0.02 ng/mL in serum or plasma · Detection time: 48 h (2 days) for 0.05 mg/kg single IV dose · Routes: IV
“Acepromazine ... 72 hrs: 0.15 mg/kg single oral dose (6 horses). ... 10 ng/mL as 2-(1- hydroxyethyl) promazine sulfoxide (HEPS)” — source p. 2

ARCI

Uniform Classification Guidelines for Foreign Substances and Recommended Penalties Model Rule p. 11 · Version 20.0 (April 10, 2026)
Controlled medication
  • Listed as: Class 3, Penalty B
“Acepromazine Atrovet, Notensil, PromAce® 3 B” — source p. 11
ARCI Controlled Therapeutic Medication Schedule for Horses p. 1 · Version 4.2.1 (Revised December 2020); policies from Model Rules Version 15 (August 2026)
Permitted up to a threshold
  • Listed as: Controlled Therapeutic Medication · Dose in the rule: Single intravenous dose of acepromazine at 0.05 milligrams per kilogram · Screening limit: 10 nanograms per / milliliter as 2-(1- hydroxyethyl) promazine sulfoxide (HEPS) in urine · Routes: IV
“Acepromazine | 10 nanograms per milliliter as 2-(1- hydroxyethyl) promazine sulfoxide (HEPS) in urine | 48 hours” — source p. 1

IFHA / EHSLC

Detection Times for Legitimate Therapeutic Substances Controlled by International Screening Limits (EHSLC) p. 1 · Undated PDF
Controlled medication
  • Listed as: Legitimate therapeutic substance controlled by International Screening Limit · Detection time: 72 h (3 days) for 0.15mg/kg, single dose · Routes: oral
“Acepromazine Sedalin® Vetoquinol UK Ltd 0.15mg/kg, single dose Oral (6) 72” — source p. 1

State racing commissions

Ace is named in the medication rules, threshold schedules or withdrawal guidance of 20 state racing commissions: Arizona, California, Colorado, Florida, Illinois, Indiana, Kentucky, Louisiana, Maine, Maryland, Minnesota, Nebraska, New York, Ohio, Oklahoma, Oregon, Pennsylvania, Texas, Washington, West Virginia. Most states publish thresholds (concentrations), not times, and several adopt the ARCI schedule by reference. ShowSafe Pro Racing layers each state's rules over HISA or ARCI the way that state applies them, for all 32 states with live pari-mutuel racing.

Detection time is not withdrawal time

A published detection time tells you how long Ace stayed detectable in a handful of horses given one dose by one route. It does not tell you when your horse is clear: a bigger dose, a different route, repeated doses, a joint injection or a slower horse all push the real figure out, and every governing body says to add a safety margin set by your veterinarian. Here is how to read the rulebook.

ShowSafe Pro takes the doses already logged for your horse, matches each one to the published row for that dose and route, adds the margin your vet set, and flags anything the studies never covered as Unknown, ask your vet instead of guessing. Every answer shows the document, page and line it came from, for every rulebook the show runs under.

Check Ace for your horseHow ShowSafe Pro works
A detection time is the approximate period a drug or its metabolite stayed detectable in the horses studied, at the dose and route studied. It is not a withdrawal time. No governing body publishes withdrawal times for you; your veterinarian sets the safety margin for your horse. Nothing on this page is a veterinary ruling or a promise that a horse will test clean. Rules change; the document, version and page behind every value are linked so you can check the current text.

Questions about Ace

Is Ace allowed at USEF shows?

The 2026 USEF Guidelines & Rules for Drugs and Medications (with 27 Jul 2026 Guidelines Update) list Ace as "Potentially Permitted with Medication Report Form (MRF) according to GR411". Not within 24 h (1 day) of competition. (Page 9.)

What is the FEI detection time for Ace?

The FEI List of Detection Times gives 72 h (3 days) for 0.15mg/kg, single dose oral (Sedalin® (Vetoquinol UK Ltd)). On the 2026 FEI Equine Prohibited Substances List Ace is a Controlled Medication. The FEI states that a detection time is not a withdrawal time; the treating veterinarian adds a safety margin.

How long before a race can a horse have Ace under HISA?

HIWU's published detection time for Ace is 72 h (3 days) for 0.15 mg/kg single oral dose (6 horses), screening limit 10 ng/mL as 2-(1-hydroxyethyl) promazine sulfoxide (HEPS) in urine; 0.02 ng/mL in serum or plasma. RMTC's advisory withdrawal guidance for the same dose is 72 h (3 days). A detection time is not a withdrawal time; HISA leaves the safety margin to your veterinarian.

Does a published detection time mean my horse will test clean?

No. It is the approximate time Ace stayed detectable in the horses studied, at that dose and route. Your horse, dose, route and number of doses may differ. Every governing body tells you to add a safety margin set by your veterinarian, and none publishes a withdrawal time. ShowSafe Pro applies the published row for the dose and route you actually gave, adds your vet's margin, and says 'Unknown' when the studies do not cover what you gave.

Other sedative medications

Dormosedan (detomidine), Rompun (xylazine), Sedivet (romifidine)

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