Breed · Horse
Quarter Horse: adverse event reports
FDA breed label "Quarter Horse" · single-breed animals only
FDA's database holds 4,224 reports where the animal's breed is given as "Quarter Horse", shown here as Quarter Horse: 23% of reports about horses. Reports on crossbred animals are left out of breed pages.
226 reports arrived in the 12 months to March 2026, up 20% from 189 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, moxidectin and omeprazole. Ivermectin + Praziquantel is named in 12.1% of this breed's reports, about the same share as in reports about all horses (14.4%).
The terms listed most often are death (9.6%), abdominal pain (7.4%) and lack of efficacy - NOS (7.1%). Death appears in 9.6% of reports, about the same share as in all horse reports (8.1%). 47.4% 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 Quarter Horse reports | Share of all horse reports |
|---|---|---|---|
| Ivermectin + Praziquantel | 510 | 12.1% | 14.4% |
| Moxidectin | 392 | 9.3% | 7.4% |
| Omeprazole | 370 | 8.8% | 9.9% |
| Ceftiofur Crystalline Free Acid | 282 | 6.7% | 4.8% |
| Detomidine Hydrochloride | 245 | 5.8% | 5.6% |
| Ivermectin | 202 | 4.8% | 4.6% |
| Pergolide mesylate | 178 | 4.2% | 6.5% |
| Flunixin Meglumine | 172 | 4.1% | 3.5% |
| Ketamine Hydrochloride | 150 | 3.6% | 3.3% |
| Pyrantel Tartrate | 144 | 3.4% | 4% |
| Clodronate | 141 | 3.3% | 1.7% |
| Firocoxib | 119 | 2.8% | 2.6% |
| Xylazine | 114 | 2.7% | 2.4% |
| Moxidectin + Praziquantel | 106 | 2.5% | 2% |
| Butorphanol Tartrate | 92 | 2.2% | 1.6% |
| Hyaluronate Sodium | 88 | 2.1% | 2.9% |
| Sucralfate | 86 | 2% | 1.7% |
| Polysulfated Glycosaminoglycan | 83 | 2% | 2.3% |
| Monensin | 53 | 1.3% | 1.6% |
| Ponazuril | 53 | 1.3% | 1.1% |
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 Quarter Horse reports listing the termall horse reports
- Death9.6%406
- Abdominal pain7.4%311
- Lack of efficacy - NOS[the product did not have the expected effect]7.1%301
- Injection site swelling[swelling where the injection was given]6.9%293
- Anorexia[not eating]6.8%288
- Depression[dull, quiet or withdrawn]6.3%268
- Diarrhoea[diarrhea]5.5%233
- Ataxia[unsteady, uncoordinated movement]5.5%231
- Recumbency[lying down and unable or unwilling to rise]4.9%208
- Death by euthanasia[the animal was euthanized]4.9%206
- Fever4.4%187
- Colic4.1%174
- Application site swelling[swelling where the product was applied]3.8%162
- Lip oedema3.6%151
- Ineffective, gastric ulcer(s)[legacy FDA term: the product did not have the expected effect (gastric ulcer(s))]3.4%143
- Injection site pain[pain where the injection was given]3%126
- Behavioural disorder NOS[behaviour change, type not specified]2.9%124
- Lethargy[unusually tired or inactive]2.9%121
- Anaphylaxis[sudden severe allergic-type reaction]2.8%120
- Urticaria[hives]2.8%119
- Collapse2.6%109
- Accidental exposure[exposure that was not intended]2.6%108
- No sign[no clinical sign was reported]2.3%97
- Lameness2.3%96
- Tachycardia[fast heart rate]2.3%96
Age and weight
Age of the animal
Weight of the animal
Coloured bar: Quarter Horse 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 | Quarter Horse | All horses |
|---|---|---|
| Reports | 4,224 | 18,382 |
| Latest 12 months | 226 | 898 |
| Classed serious, of reports stating it | 47.4% | 44.1% |
| Death or euthanasia recorded, per 1,000 reports | 154.4 | 136 |
Questions about Quarter Horse reports
How many FDA adverse event reports involve Quarter Horses?
4,224 reports through March 2026, 23% of reports about horses; 226 in the latest 12 months.
Which drugs are named most often in Quarter Horse reports?
By active ingredient: ivermectin + praziquantel (510), moxidectin (392), omeprazole (370), ceftiofur crystalline free acid (282) and detomidine hydrochloride (245). Brands are masked in the public data.
What signs are reported most for this breed?
death (9.6%), abdominal pain (7.4%), lack of efficacy - NOS (7.1%), injection site swelling (6.9%) and anorexia (6.8%).
Is the Quarter Horse 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 Quarter Horse 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 ("Quarter Horse" becomes "Quarter Horse"). 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.