Osphos (clodronate) is a bisphosphonate, also sold as Clodronate Disodium, Clodronic Acid, Osphos. Below: how 6 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 720 h (30 days)HISA: Banned / prohibitednamed in the rules of 1 state racing commission
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 document | Dose and route studied | Formulation | Horses | Detection time |
|---|---|---|---|---|
| USEF (US Equestrian) 2026 (last revised 1 Dec 2025; amendments effect… p. 11 | dose not stated in the row | 672 h (28 days) plasma / urine | ||
| FEI 2024 (16 December 2024) p. 1 | 1.53mg/kg · IM | Osphos (Dechra) | 35 | 720 h (30 days) |
Transcribed from the governing bodies' own documents. Each entry links to the document and quotes the row it came from.
“Potentially Permitted with Medication Report Form (MRF) according to GR411: ... clodronate disodium (bisphosponate; Osphos®)” — source p. 9
“CONTROLLED Clodronic Acid Bisphosphonate” — source p. 9
“CLODRONIC ACID Osphos 1.53mg/kg i.m 35 720 (30d) Dechra” — source p. 1
From 2027-01-01: 2027 Equine Prohibited Substances List p. 10 lists it as Controlled Medication.
“Clodronate” — source p. 11
“Clodronate ... Conditionally Permitted ... Conditionally permitted substances require a 24-hour withdrawal prior to the horse competing.” — source
“Clodronate (Clodronic acid) ... Bisphosphonate” — source p. 19
“Clodronate OsPhos 3 A” — source p. 21
Osphos is named in the medication rules, threshold schedules or withdrawal guidance of 1 state racing commission: Washington. 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.
A published detection time tells you how long Osphos 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.
The 2026 USEF Guidelines & Rules for Drugs and Medications (with 27 Jul 2026 Guidelines Update) list Osphos as "Potentially Permitted with Medication Report Form (MRF) according to GR411". Not within 24 h (1 day) of competition. (Page 9.)
The FEI List of Detection Times gives 720 h (30 days) for 1.53mg/kg IM (Osphos (Dechra)). On the 2026 FEI Equine Prohibited Substances List Osphos is a Controlled Medication. The FEI states that a detection time is not a withdrawal time; the treating veterinarian adds a safety margin.
No. It is the approximate time Osphos 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.