Species
Horse: adverse event reports
18,382 reports, 1.4% of FDA's animal drug adverse event database
18,382 adverse event reports in FDA's database concern horses: 1.4% of all reports received from January 1987 to March 2026. 898 arrived in the 12 months to March 2026, up 17% from 766 in the 12 months before. That is 1.2% of all reports received in those 12 months and about 468 reports a year over the whole record.
By active ingredient, the drugs named most often are ivermectin + praziquantel (14.4% of horse reports), omeprazole (9.9% of horse reports), moxidectin (7.4% of horse reports) and pergolide mesylate (6.5% of horse reports). Drugs given to the most animals lead the list for that reason; brands are masked in the public data.
The terms listed most often are death (8.1%), lack of efficacy - NOS (7.6%) and abdominal pain (6.6%). 44.1% of reports stating seriousness were classed as serious (38.6% across all species), and 13.6% record a death or euthanasia (6.4% overall).
FDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases.
Drugs named most often, by active ingredient
| Active ingredients recorded for the drug | Reports | Share of horse reports | Share of the drug's reports that concern horses |
|---|---|---|---|
| Ivermectin + Praziquantel | 2,638 | 14.4% | 78% |
| Omeprazole | 1,820 | 9.9% | 49.7% |
| Moxidectin | 1,367 | 7.4% | 2.4% |
| Pergolide mesylate | 1,188 | 6.5% | 86.5% |
| Detomidine Hydrochloride | 1,024 | 5.6% | 80.6% |
| Ceftiofur Crystalline Free Acid | 882 | 4.8% | 41.4% |
| Ivermectin | 854 | 4.6% | 4.3% |
| Pyrantel Tartrate | 739 | 4% | 72.2% |
| Flunixin Meglumine | 643 | 3.5% | 43.8% |
| Ketamine Hydrochloride | 611 | 3.3% | 8.5% |
| Hyaluronate Sodium | 531 | 2.9% | 47.5% |
| Firocoxib | 486 | 2.6% | 5.1% |
| Xylazine | 442 | 2.4% | 39.6% |
| Polysulfated Glycosaminoglycan | 415 | 2.3% | 7.2% |
| Moxidectin + Praziquantel | 371 | 2% | 66.4% |
| Sucralfate | 318 | 1.7% | 23.1% |
| Clodronate | 305 | 1.7% | 97.1% |
| Monensin | 303 | 1.6% | 6.3% |
| Butorphanol Tartrate | 295 | 1.6% | 3.9% |
| Oxibendazole | 209 | 1.1% | 12.1% |
| Pyrantel Pamoate | 208 | 1.1% | 3.5% |
| Ponazuril | 200 | 1.1% | 41.6% |
| Pentosan polysulfate sodium | 181 | 1% | 92.8% |
| Vitamin E | 153 | 0.8% | 12.9% |
| Phenylbutazone | 146 | 0.8% | 66.7% |
| Altrenogest | 128 | 0.7% | 26.2% |
| Ceftiofur Sodium | 124 | 0.7% | 9% |
| Triamcinolone Acetonide | 117 | 0.6% | 8.1% |
| Clenbuterol Hydrochloride | 100 | 0.5% | 68% |
| Penicillin G Procaine | 99 | 0.5% | 13.6% |
Ordered by report count, which follows how widely a drug is used. FDA states that these data "cannot be used to estimate the risk associated with the product or compare one drug or device product with another". openFDA masks brand and manufacturer names in adverse event records, so the reports counted here cannot be attributed to a particular brand.
Signs listed in reports
share of horse reports listing the termall species
- Death8.1%1,490
- Lack of efficacy - NOS[the product did not have the expected effect]7.6%1,396
- Abdominal pain6.6%1,214
- Anorexia[not eating]6.3%1,161
- Injection site swelling[swelling where the injection was given]5.5%1,010
- Diarrhoea[diarrhea]5.3%979
- Depression[dull, quiet or withdrawn]5.1%944
- Ataxia[unsteady, uncoordinated movement]4.8%875
- Application site swelling[swelling where the product was applied]4.6%852
- Lip oedema4.6%847
- Fever4.5%820
- Ineffective, gastric ulcer(s)[legacy FDA term: the product did not have the expected effect (gastric ulcer(s))]4.4%809
- Death by euthanasia[the animal was euthanized]4.2%772
- Colic4%738
- Recumbency[lying down and unable or unwilling to rise]3.9%708
- Anaphylaxis[sudden severe allergic-type reaction]2.8%515
- Lethargy[unusually tired or inactive]2.8%511
- No sign[no clinical sign was reported]2.7%501
- Behavioural disorder NOS[behaviour change, type not specified]2.7%496
- Ineffective, sedation[legacy FDA term: the product did not have the expected effect (sedation)]2.7%496
- Accidental exposure[exposure that was not intended]2.7%488
- Lameness2.6%479
- Injection site pain[pain where the injection was given]2.6%474
- Hypersalivation[drooling]2.4%445
- Urticaria[hives]2.3%417
- Ineffective, anesthesia[legacy FDA term: the product did not have the expected effect (anesthesia)]2.2%410
- Collapse2.2%407
- Tachycardia[fast heart rate]2%375
- Hyperhidrosis1.8%336
- Tachypnoea[fast breathing]1.8%332
Single ingredients, pooled across combinations
- Ivermectin3,499 reports · 19%
- Praziquantel3,005 reports · 16.3%
- Omeprazole1,821 reports · 9.9%
- Moxidectin1,735 reports · 9.4%
- Pergolide mesylate1,188 reports · 6.5%
- Detomidine Hydrochloride1,025 reports · 5.6%
- Ceftiofur Crystalline Free Acid882 reports · 4.8%
- Pyrantel Tartrate739 reports · 4%
- Flunixin Meglumine643 reports · 3.5%
- Ketamine Hydrochloride612 reports · 3.3%
- Hyaluronate Sodium531 reports · 2.9%
- Firocoxib486 reports · 2.6%
- Xylazine443 reports · 2.4%
- Polysulfated Glycosaminoglycan415 reports · 2.3%
- Sucralfate318 reports · 1.7%
- Clodronate305 reports · 1.7%
Age and weight
Age of the animal
Weight of the animal
Outcomes and report types
Outcome recorded in the report
What kind of report it was
Coloured bar: horse reports. Grey bar: all 1,357,245 reports. Outcomes are as stated by the reporter.
Trend
Reports by month FDA received them. The newest months are incomplete because FDA posts reports with a delay of three to six months.
| Measure | Horse | All reports |
|---|---|---|
| Reports | 18,382 | 1,357,245 |
| Classed serious, of reports stating it | 44.1% | 38.6% |
| Death or euthanasia recorded, per 1,000 reports | 135.6 | 63.8 |
| Filed as lack of expected effectiveness (wholly or partly) | 14.5% | 23% |
Breeds with their own page
- Quarter Horse4,224 reports · 23% of horse reports
- Thoroughbred2,064 reports · 11.2% of horse reports
- Arab822 reports · 4.5% of horse reports
- Paint645 reports · 3.5% of horse reports
- Warmblood525 reports · 2.9% of horse reports
- Miniature379 reports · 2.1% of horse reports
- Standardbred347 reports · 1.9% of horse reports
- Tennessee Walking Horse311 reports · 1.7% of horse reports
- Appaloosa297 reports · 1.6% of horse reports
- Dutch Warmblood223 reports · 1.2% of horse reports
- Morgan219 reports · 1.2% of horse reports
- Hanovarian173 reports · 0.9% of horse reports
- American Saddlebred166 reports · 0.9% of horse reports
- Pony144 reports · 0.8% of horse reports
Single-breed labels with at least 100 reports. Crossbred animals count in the species total only.
Questions about horse reports
How many adverse event reports involve horses?
18,382 reports through March 2026, 1.4% of the database; 898 in the latest 12 months.
Which drugs are reported most often for horses?
By active ingredient: ivermectin + praziquantel (2,638), omeprazole (1,820), moxidectin (1,367), pergolide mesylate (1,188) and detomidine hydrochloride (1,024). The order tracks how widely each is used; brands are masked in the public data.
What signs are reported most in horses?
death (8.1%), lack of efficacy - NOS (7.6%), abdominal pain (6.6%), anorexia (6.3%) and injection site swelling (5.5%).
What ages are the horses in these reports?
12 years and over (32.9%), 8 to 11 years (12.5%) and 4 to 7 years (12.4%); age is not given in 28.1% of reports.
Do more reports mean more risk for this species?
No. Counts follow how many animals are treated and how readily their owners and veterinarians report. FDA states that "there is no certainty that the reported drug or device caused the adverse event" and that the event "may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources."
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 30 Sep 2026. 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.