Among the 1.34 million adverse-event reports in the FDA CVM openFDA database, one category demands particular attention: reports where the animal died or was euthanized. These 85,693 fatal-outcome reports — representing 6.4% of the total database — are the subject of this analysis.

Every number below comes from a direct computation of the openFDA animal adverse-event dataset (analysis run date: 2026-06-09). As with all pharmacovigilance data, these reports reflect suspected associations, not confirmed causalities. A report listing "Died" as an outcome means someone reported a death that they associated with a drug exposure — it does not mean the drug caused the death.

Fatal outcomes at a glance

The database tracks six outcome categories. For this analysis, "fatal" combines Died and Euthanized outcomes (deduplicating reports that list both):

Euthanasia accounts for roughly 23% of fatal outcomes. In many cases, the euthanasia decision reflects the underlying disease (cancer, organ failure) or the severity of the adverse event (seizures unresponsive to treatment, irreversible organ damage), rather than a direct drug toxicity.

Fatal reports by species

The fatal-report rate varies dramatically by species — driven by differences in the types of drugs used, the conditions treated, and the economics of veterinary care:

Food-animal species (cattle, pigs, sheep, goats, poultry) show high fatal-report rates. This reflects several factors: many reports for these species involve serious disease outbreaks (respiratory disease complexes, reproductive losses) where the drug was being used to treat an already life-threatening condition; and economic considerations in food-animal medicine often mean that animals with poor prognoses are euthanized rather than treated intensively.

Dogs, despite having the highest absolute count of fatal reports (53,170), have a relatively low fatal rate (5.5%) because the companion-animal reporting pool is dominated by non-fatal events — GI upset, lethargy, palatability complaints — associated with routine parasiticide and therapeutic use.

Cats show a 9.5% fatal rate — nearly double the canine rate. This may reflect the well-documented sensitivity of cats to certain drug classes (permethrins, NSAIDs, acetaminophen) and the fact that cats are more likely to be presented in an emergency context after accidental ingestion or inappropriate product application.

Which active ingredients appear most often in fatal reports

The top 20 ingredients by fatal-report count among the 85,693 fatal reports:

NSAIDs: the highest fatal-report counts among therapeutics

Carprofen (17.0% fatal rate), meloxicam (12.7%), deracoxib (19.2%), and firocoxib (17.4%) — all veterinary NSAIDs — appear prominently in the fatal-report list. This does not mean these drugs are uniquely dangerous. Rather, they are:

• Prescribed for chronic conditions (osteoarthritis, post-surgical pain) in older animals with comorbidities.

• Often used long-term, increasing the window for adverse events to occur.

• Associated with well-characterized risks (GI ulceration, renal toxicity, hepatic toxicity) that can be serious when they occur.

The 17.0% fatal-report rate for carprofen reflects a population of geriatric dogs with pre-existing conditions, not a toxicity rate per dose administered.

Monoclonal antibodies: bedinvetmab

Bedinvetmab (Librela) — the anti-NGF monoclonal antibody for canine osteoarthritis pain — has 3,434 fatal reports out of 17,894 total reports (19.2%). As a newer therapy (FDA-approved in May 2023), it attracted intense early reporting attention. The AVMA reported in 2024 that the FDA was monitoring adverse events associated with the drug, including death and euthanasia outcomes. Many of these reports involve geriatric dogs with advanced OA and multiple comorbidities.

Maropitant and cefovecin: high fatal rates in context

Maropitant citrate (Cerenia) shows a 21.1% fatal rate (2,663 fatal out of 12,594 total reports). Cefovecin (Convenia) shows 20.4% (1,880 out of 9,194). Both are injectable drugs commonly administered in clinic settings to animals that may already be sick — maropitant for vomiting (which can signal serious underlying disease), cefovecin as a long-acting antibiotic (often for infections in compromised patients). The high fatal rates likely reflect the severity of the underlying conditions being treated rather than drug-specific toxicity.

Food-animal antibiotics and ionophores

Tulathromycin (55.0% fatal rate) and monensin sodium (51.8%) are primarily used in cattle. Tulathromycin is a macrolide antibiotic for bovine respiratory disease — a condition with significant mortality in feedlot cattle. Monensin is an ionophore used as a rumen modifier and coccidiostat; toxicity from accidental overdose (especially in horses) is well-documented. The high fatal rates reflect both the severity of the diseases being treated and the toxicity profile of these compounds when misused.

The most common reactions in fatal reports

The top 25 reactions co-reported with fatal outcomes:

The top non-death reactions in fatal reports paint a clinical picture: GI signs (vomiting, anorexia, diarrhea) dominate, followed by laboratory markers of organ dysfunction (elevated BUN, ALT, creatinine, SAP, bilirubin — reflecting renal and hepatic involvement), neurologic signs (seizures, ataxia), and hematologic abnormalities (anemia, leukocytosis).

The elevated BUN and creatinine entries (5,506 and 4,246 respectively) suggest that renal failure — whether drug-induced or secondary to the underlying condition — is a common pathway in fatal reports. Similarly, elevated ALT and SAP (4,966 and 4,631) point to hepatic involvement.

Fatal reports over time

The annual count of fatal reports has remained relatively stable over the past two decades, with a notable increase in 2024:

The 2024 jump (5,548 fatal reports, up from 3,324 in 2023) coincides with increased reporting activity overall (81,145 total reports in 2024 vs. 65,368 in 2023) and the introduction of new therapeutic classes (monoclonal antibodies). Whether this reflects a genuine safety signal or simply higher reporting volume cannot be determined from report counts alone.

Species-specific fatal patterns

Dogs (53,170 fatal reports)

Dogs account for 62.0% of all fatal reports. The leading fatal-report ingredients mirror the overall list: carprofen (most of its 8,676 fatal reports are canine), spinosad, milbemycin oxime, and ivermectin. NSAID-related fatal reports are predominantly canine given the labeled use of carprofen, deracoxib, meloxicam, and firocoxib in dogs.

Cats (13,849 fatal reports — 9.5% fatal rate)

Cats have a notably higher fatal-report rate than dogs (9.5% vs. 5.5%). Contributing factors likely include:

• Permethrin toxicity. Application of dog-labeled permethrin-containing flea products to cats remains a source of severe and sometimes fatal neurotoxicity, despite decades of warning labels.

• NSAID sensitivity. Cats are more susceptible to NSAID-related renal and GI toxicity than dogs, and some fatal reports involve inappropriate dosing or species mix-ups.

• Presentation bias. Cats are notoriously adept at hiding illness and may be presented later in the disease course, when outcomes are poorer.

Cattle (11,429 fatal reports — 36.8% fatal rate)

The bovine fatal reports are dominated by respiratory disease treatments (tulathromycin, tildipirosin, gamithromycin) and vaccine-related reports. Cattle respiratory disease complex (shipping fever) carries high mortality, and many reports involve animals that were already severely ill.

Horses (2,468 fatal reports — 13.6% fatal rate)

Equine fatal reports include monensin toxicity (accidental contamination of horse feed with cattle ionophore supplements is a well-known hazard), NSAID complications (phenylbutazone), and adverse reactions to vaccines and anthelmintics.

What these numbers can and cannot tell you

What they can tell you

• Which drug classes have the most reported fatal associations, helping prioritize monitoring and research.

• Which species have higher fatal-report rates relative to their total reporting volume.

• The clinical presentation patterns (GI, renal, hepatic, neurologic) that most commonly accompany fatal reports.

What they cannot tell you

• The probability that a given drug will cause a fatal reaction. Without knowing how many doses were administered (the denominator), you cannot calculate incidence.

• Whether the drug caused the death. Most reports involve animals with pre-existing disease. Carprofen given to a 12-year-old dog with OA, kidney disease, and a heart murmur that dies weeks later may be reported as a fatal adverse event — but the underlying conditions are the more proximate cause.

• Comparative drug safety. Drug A with 500 fatal reports out of 10 million doses is safer per dose than Drug B with 100 fatal reports out of 100,000 doses — but the database does not provide the dose denominator.

How to report

If you suspect an adverse event in an animal — fatal or not — you can report it through:

• The drug manufacturer (required for manufacturers to forward to the FDA).

• The FDA Safety Reporting Portal: https://www.fda.gov/animal-veterinary/report-problem/how-report-animal-drug-and-device-side-effects-and-product-problems

Every report strengthens the pharmacovigilance system.

Sources

• FDA Center for Veterinary Medicine. "Adverse Event Reports for Animal Drugs and Devices." https://www.fda.gov/animal-veterinary/product-safety-information/adverse-event-reports-animal-drugs-and-devices

• FDA. "openFDA Animal & Veterinary Adverse Events API." https://open.fda.gov/apis/animalandveterinary/event/

• AVMA. "FDA: Adverse events in dogs reported with monoclonal antibody drug." 2024. https://www.avma.org/news/fda-adverse-events-dogs-reported-monoclonal-antibody-drug

• FDA. "How to Report Animal Drug and Device Side Effects and Product Problems." https://www.fda.gov/animal-veterinary/report-problem/how-report-animal-drug-and-device-side-effects-and-product-problems

• Data source: FDA CVM animal drug adverse-event reports (openFDA), downloaded 2026-06-09; analysis run date 2026-06-09. 1,340,077 individual reports analyzed; 85,693 reports with Died and/or Euthanized outcomes identified. Reaction terms follow VeDDRA coding.