Breed · Horse
Thoroughbred: adverse event reports
FDA breed label "Thoroughbred" · single-breed animals only
2,064 adverse event reports received by FDA describe an animal recorded as Thoroughbred (FDA breed label "Thoroughbred"). That is 11.2% of all reports about horses. Crossbred animals are not counted here, only reports that give this single breed.
93 reports arrived in the 12 months to March 2026, up 50% from 62 in the 12 months before. A breed's count mostly mirrors how common the breed is; registration and ownership figures by breed are not public data, so no per-animal rate can be given.
By active ingredient, the drugs named most often are ivermectin + praziquantel, omeprazole and ceftiofur crystalline free acid. Ivermectin + Praziquantel is named in 17.3% of this breed's reports, about the same share as in reports about all horses (14.4%).
The terms listed most often are injection site swelling (8.6%), lack of efficacy - NOS (8.2%) and ineffective, gastric ulcer(s) (7.8%). Injection site swelling appears in 8.6% of reports, a larger share than in all horse reports (5.5%). 46% of reports stating seriousness were classed as serious, against 44.1% for horses overall.
Drugs named most often, by active ingredient
| Active ingredients recorded for the drug | Reports | Share of Thoroughbred reports | Share of all horse reports |
|---|---|---|---|
| Ivermectin + Praziquantel | 358 | 17.3% | 14.4% |
| Omeprazole | 318 | 15.4% | 9.9% |
| Ceftiofur Crystalline Free Acid | 155 | 7.5% | 4.8% |
| Detomidine Hydrochloride | 106 | 5.1% | 5.6% |
| Moxidectin | 85 | 4.1% | 7.4% |
| Flunixin Meglumine | 76 | 3.7% | 3.5% |
| Ivermectin | 75 | 3.6% | 4.6% |
| Pyrantel Tartrate | 65 | 3.1% | 4% |
| Hyaluronate Sodium | 64 | 3.1% | 2.9% |
| Pergolide mesylate | 56 | 2.7% | 6.5% |
| Sucralfate | 54 | 2.6% | 1.7% |
| Polysulfated Glycosaminoglycan | 50 | 2.4% | 2.3% |
| Firocoxib | 44 | 2.1% | 2.6% |
| Moxidectin + Praziquantel | 38 | 1.8% | 2% |
| Vitamin E | 38 | 1.8% | 0.8% |
| Pyrantel Pamoate | 35 | 1.7% | 1.1% |
| Butorphanol Tartrate | 32 | 1.6% | 1.6% |
| Ketamine Hydrochloride | 29 | 1.4% | 3.3% |
| Ponazuril | 28 | 1.4% | 1.1% |
| Clodronate | 27 | 1.3% | 1.7% |
Ordered by report count. Differences from the species column often come from body size (which drugs a breed is prescribed) and from how common the breed was in the years a drug sold most. FDA states that these data cannot be used to estimate risk or to compare one product with another. Brand and manufacturer names are masked by FDA in these records.
Signs listed in reports
share of Thoroughbred reports listing the termall horse reports
- Injection site swelling[swelling where the injection was given]8.6%177
- Lack of efficacy - NOS[the product did not have the expected effect]8.2%169
- Ineffective, gastric ulcer(s)[legacy FDA term: the product did not have the expected effect (gastric ulcer(s))]7.8%160
- Death7%145
- Fever7%145
- Abdominal pain7%144
- Anorexia[not eating]6.3%131
- Lip oedema6.2%128
- Application site swelling[swelling where the product was applied]6%124
- Death by euthanasia[the animal was euthanized]4.9%101
- Anaphylaxis[sudden severe allergic-type reaction]4.7%97
- Ataxia[unsteady, uncoordinated movement]4.6%95
- Depression[dull, quiet or withdrawn]4.6%94
- Injection site pain[pain where the injection was given]4.4%91
- Diarrhoea[diarrhea]4.2%86
- Colic4%83
- Recumbency[lying down and unable or unwilling to rise]3.9%80
- Hypersalivation[drooling]3.5%72
- Lameness3%61
- Collapse2.6%53
- Swollen mouth2.5%52
- Tachycardia[fast heart rate]2.5%52
- Urticaria[hives]2.5%52
- Tongue oedema2.2%46
- Behavioural disorder NOS[behaviour change, type not specified]2.2%45
Age and weight
Age of the animal
Weight of the animal
Coloured bar: Thoroughbred reports. Grey bar: all horse reports.
Trend and outcomes
Reports by month FDA received them. The newest months are incomplete because FDA posts reports with a delay of three to six months.
Outcome recorded in the report
Beside all horses
| Measure | Thoroughbred | All horses |
|---|---|---|
| Reports | 2,064 | 18,382 |
| Latest 12 months | 93 | 898 |
| Classed serious, of reports stating it | 46% | 44.1% |
| Death or euthanasia recorded, per 1,000 reports | 123.1 | 136 |
Questions about Thoroughbred reports
How many FDA adverse event reports involve Thoroughbreds?
2,064 reports through March 2026, 11.2% of reports about horses; 93 in the latest 12 months.
Which drugs are named most often in Thoroughbred reports?
By active ingredient: ivermectin + praziquantel (358), omeprazole (318), ceftiofur crystalline free acid (155), detomidine hydrochloride (106) and moxidectin (85). Brands are masked in the public data.
What signs are reported most for this breed?
injection site swelling (8.6%), lack of efficacy - NOS (8.2%), ineffective, gastric ulcer(s) (7.8%), death (7%) and fever (7%).
Is the Thoroughbred more sensitive to certain drugs?
Report counts cannot answer that. They show what was reported, not what a drug did, and they are not adjusted for how many Thoroughbred animals exist or were treated. Breed-related drug sensitivities that are established are described on FDA-approved labels; a veterinarian is the person to ask about an individual animal.
Why are crossbreds not included?
FDA records crossbred animals with one or more component breeds. Counting them under each component would double count, so breed pages use single-breed reports only. Crossbreds remain in the species totals.
How do I report a problem?
Call the drug company using the number on the label, or send Form FDA 1932a to FDA. See the guide on how to report.
Where this comes from. Counts are built from the openFDA Animal & Veterinary adverse event bulk files released 28 Sep 2026, which hold reports FDA's Center for Veterinary Medicine received through 31 Mar 2026. openFDA masks brand and manufacturer names in these files, so drugs are counted by the active ingredients each record discloses and no figure is attributed to a brand, application or company. Ingredient names, and the separate reference lists of approved products, follow the FDA Green Book as of 1 Oct 2026. Breed names are FDA's labels rearranged into everyday order ("Thoroughbred" becomes "Thoroughbred"). No report text, lot numbers or reporter details are published. See the methodology and sources; FDA's record is authoritative, and corrections are handled within five working days.