Guide
Understanding Animal Adverse Event Reports
What the FDA collects, how reports are submitted, and what this data can, and cannot, tell you about your pet's medications.
Key Takeaway
The FDA's openFDA database holds over 1 million animal adverse event reports covering 506 breeds and 2,558 drugs. These reports flag potential safety concerns, they do not prove causation. The database is a signal-detection tool, not a definitive risk scorecard. Used correctly, it helps pet owners ask better questions before and after a veterinarian prescribes a medication.
What Is an Adverse Event Report?
An animal adverse event report is a formal record submitted to the U.S. Food and Drug Administration describing an unexpected or harmful reaction that occurred in an animal after receiving a veterinary drug, biological product, or medical device. The FDA's Center for Veterinary Medicine (CVM) receives these reports and stores them in a publicly accessible database called openFDA.
Each report captures key details: the animal's species, breed, age, sex, and weight; the drug or product involved; the dose and duration of use; the reaction that was observed; and the outcome, ranging from full recovery to death. Some reports include a veterinarian's assessment of whether the drug was likely responsible. Others are submitted directly by pet owners without veterinary evaluation.
PlainBreed makes this data searchable by breed, drug, and reaction type, so you can quickly find reports most relevant to your pet.
How the FDA Collects Reports
Report submissions come through two channels. Drug manufacturers are required by federal law to report adverse events that come to their attention, this includes reports forwarded to them by veterinarians or pet owners who contact the company directly. Veterinarians and pet owners can also submit reports voluntarily through the FDA's Safety Reporting Portal or by calling the drug manufacturer.
Because most reporting is voluntary, the FDA consistently notes that adverse events are underreported. The true number of reactions in the field is likely higher than what appears in the database. Events that are mild, brief, or attributed to other causes are less likely to be reported. This means the database is more useful for identifying serious or recurring patterns than for estimating the absolute frequency of any reaction.
Reporting volume has grown over time as awareness of the database has increased and electronic submission has become easier. Reports from the past five years tend to be more detailed than older ones, reflecting improvements in the FDA's data collection forms.
What Reports Can and Cannot Tell You
The most important thing to understand about adverse event data is that it records association, not causation. An animal that experienced vomiting after receiving a flea medication may have had a gastrointestinal condition unrelated to the drug, consumed something harmful around the same time, or been reacting to a different product administered simultaneously. The report captures the temporal association, the reaction happened while the drug was being used, but cannot establish that the drug was responsible.
What the data does well is surface patterns. If a particular drug has hundreds of reports describing the same reaction type, especially serious outcomes like seizures or cardiac events, that pattern warrants attention even before causation is proven. The FDA's pharmacovigilance program is designed to detect exactly these kinds of signals and investigate further.
For pet owners, the practical value of this data is in preparation and communication. Before your pet starts a new medication, reviewing its drug profile on PlainBreed can help you identify which reactions have been reported most often and what outcomes were documented. This gives you specific questions to raise with your veterinarian.
How the FDA Acts on Report Data
The FDA's Center for Veterinary Medicine reviews incoming reports continuously and uses statistical methods to detect safety signals, situations where a drug is associated with a particular reaction more often than would be expected by chance. When a signal is identified, the FDA may:
- Request additional clinical or epidemiological studies from the drug manufacturer
- Update the product's prescribing information or package insert to add new warnings
- Issue a public safety communication or drug safety update
- Require a label change that restricts use or adds contraindications
- In rare cases, work with the manufacturer on a voluntary recall or market withdrawal
Several veterinary drugs have had their labels updated or use restricted based on adverse event signal data. This ongoing post-market surveillance is one of the primary reasons the FDA maintains the public database.
Frequently Asked Questions
What is an animal adverse event report?
An animal adverse event report is a record submitted to the FDA describing an unexpected or harmful reaction experienced by an animal after receiving a veterinary drug or product. Reports may be filed by veterinarians, pet owners, or drug manufacturers. Each report captures details such as the animal species, breed, drug name, and the nature of the reaction observed.
Who submits adverse event reports to the FDA?
Reports come from three main sources: drug manufacturers (who are legally required to submit reports they receive), licensed veterinarians, and pet owners or animal caretakers. Manufacturer reporting is mandatory under federal law. Veterinarian and owner reporting is voluntary. Because reporting is largely voluntary, the FDA acknowledges that adverse events are underreported in the database.
Does an adverse event report prove a drug caused harm?
No. An adverse event report records an association, an animal experienced a reaction while or after receiving a drug, but does not establish that the drug caused the reaction. The animal may have had a pre-existing condition, been exposed to other substances, or the event may have been coincidental. The FDA uses these reports to detect safety signals and investigate further, not as proof of causation.
How does the FDA use adverse event data?
The FDA Center for Veterinary Medicine (CVM) analyzes adverse event reports to identify safety signals, patterns suggesting a drug may carry previously unknown risks. When signals are detected, the FDA may request additional studies from the manufacturer, update product labeling, issue safety communications, or in rare cases restrict or withdraw a product from the market. The data also informs post-market surveillance programs.
What does "serious" mean in an adverse event report?
The FDA classifies adverse events by outcome. Serious outcomes include death, life-threatening reactions, hospitalization or significant disability, and congenital abnormalities. Non-serious outcomes include temporary or minor reactions that resolve without lasting harm. PlainBreed surfaces outcome data so you can filter by severity and understand the full range of documented reactions for any breed or drug.
How current is the PlainBreed database?
PlainBreed sources data from the FDA openFDA Animal & Veterinary Adverse Events endpoint, which is updated quarterly. Our database covers reports from 2010 through the most recent available update, representing over 1 million individual reports across 506 breeds, 53 species, and 2,558 drugs.
Sources
- U.S. FDA openFDA, Animal & Veterinary Adverse Events API (api.fda.gov/animalandveterinary)
- FDA Center for Veterinary Medicine, Adverse Event Reporting (fda.gov/animal-veterinary)
- FDA, Understanding Unapproved Use of Approved Drugs "Off Label"
- PlainBreed database, 1M+ reports, 2004–2025 (openFDA source)
This content is for informational purposes only and does not constitute veterinary advice. Consult your veterinarian about your pet's medications.
The live report counts and ratios linked from this guide are rendered directly from FDA openFDA adverse event data. Worked examples and illustrative numbers cited in the guide text are for explaining the method, not drawn from this portal's live database. This page's data-linked figures draw directly on FDA openFDA data. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.
Frequently asked questions
Where does this data come from?
Every figure derives from the U.S. FDA Center for Veterinary Medicine (CVM) animal drug adverse event reporting program, accessed through the openFDA animal & veterinary endpoint. We use no proprietary aggregators and no estimated data, see the methodology page for the exact source and extract date.
Do these reports prove a medication is dangerous?
No. Adverse event reports are voluntary and unverified. A report means only that someone observed a health event after a product was used, it does not establish that the product caused it. Always consult your veterinarian before starting, changing, or stopping any medication.
Why does one breed have far more reports than another?
Report volume is driven mostly by how common a breed is and how actively its owners and veterinarians file reports. A popular breed such as the Labrador Retriever sits near the top because the breed is enormous in number, not because it faces unusual risk.
How often is the data updated?
We refresh from the FDA CVM extract periodically. The current extract date is shown on the methodology page.