Pet Drug Reports

Fentanyladverse event reports that FDA received

Active ingredient

The Green Book lists no brand name for exactly this active ingredient.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Read this first. FDA says this about the data:

An API dataset query result cannot be used to estimate the risk associated with the product or compare one drug or device product with another. When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event. This dataset should not be the sole source of information for clinical decision-making or other assumptions about the safety or effectiveness of a product. The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine publishes these words. Source: Adverse Event Reports for Animal Drugs and Devices, read on . The data have the reports that FDA received through .

This page is not veterinary advice. For an animal that is ill, speak to a veterinarian.

Contacting a veterinarianHow to report to FDA

From December 1998 to May 2026, FDA received 736 adverse event reports that name a drug with fentanyl as its active ingredient. Of the 736 reports, 624 (84.8%) are about dogs. 80 reports are about cats (10.9%).

In January to March 2026, FDA received 13 reports that name this drug. The signs that appear in the largest number of the 736 reports are "Anorexia", "Lethargy" and "Vocalisation". A report is not proof that a drug caused a sign.

Reports that name this drug fell by 15.1% in the 12 months to June 2026, compared with the 12 months before. Reports for all animal drugs fell by 4.6% in the same periods. The newest months can get more reports in a later update. Reports about dogs are 84.8% of the reports that name this drug, and 72.6% of all reports.

Since the last update of the FDA data

The latest update of the FDA data, recorded on , changed no count of this page.

January to March 2026 is the latest closed quarter in the data. In that quarter FDA received 13 reports that name fentanyl: 10 dog, 3 cat, 0 horse, 0 other or not given.

All updatesFeed of updates (RSS)

Signs that the reports list

A sign is a coded term from the report. The words in brackets are a plain gloss of the term. The percentage is the share of the 736 reports that list the sign. One report can list more than one sign.

The sign that is in the largest number of the reports comes first.

  1. Anorexia[not eating]21.1%155 reports
  2. Lethargy[unusually tired or inactive]15.6%115 reports
  3. Vocalisation[crying out or unusual noise]15.4%113 reports
  4. Death by euthanasia[the animal was euthanized]13.9%102 reports
  5. Vomiting12.6%93 reports
  6. Hypothermia[low body temperature]11.8%87 reports
  7. Sedation11.1%82 reports
  8. Not eating11%81 reports
  9. Other abnormal test result NOS[abnormal laboratory result, type not specified]9.1%67 reports
  10. Death9%66 reports
  11. Diarrhoea[diarrhea]9%66 reports
  12. Lack of efficacy - NOS[the product did not have the expected effect]8.8%65 reports
  13. Inappetence[reduced appetite]8.2%60 reports
  14. Behavioural disorder NOS[behaviour change, type not specified]6.9%51 reports
Show the next 16 signs
  1. Adipsia[not drinking]6.4%47 reports
  2. Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]6.4%47 reports
  3. Panting5.8%43 reports
  4. Pain NOS[NOS: not otherwise specified]5.6%41 reports
  5. Not drinking5.4%40 reports
  6. Anxiety5.3%39 reports
  7. Decreased appetite5.3%39 reports
  8. Abnormal radiograph finding5.2%38 reports
  9. Regurgitation5.2%38 reports
  10. Fever5%37 reports
  11. Bradycardia[slow heart rate]4.9%36 reports
  12. Dehydration4.9%36 reports
  13. Emesis[vomiting]4.8%35 reports
  14. Hypotension[low blood pressure]4.6%34 reports
  15. Nausea4.6%34 reports
  16. Restlessness4.5%33 reports

The list shows 30 of 865 coded signs. A report is not proof that a drug caused a sign. Download all signs (CSV)

Reports by species

  • Dog84.8%624
  • Cat10.9%80
  • Human exposure1.2%9
  • Goat0.4%3
  • Alpaca0.3%2
  • Pig0.3%2

The share is of all 736 reports that name fentanyl. The other reports give a different species or no species.

Reports for each month, Jul 2021 to Jun 2026

Dog112 reports. Largest count in one month: 9 (Dec 2024)
Cat48 reports. Largest count in one month: 5 (Dec 2024)
Horse0 reports

No chart: no month has 5 or more reports.

Other or not given1 report

No chart: no month has 5 or more reports.

The month is the month in which FDA received the report. Each chart has its own scale. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

Reports by year

  • Dog
  • Cat
  • Horse
  • Other or not given
Reports that name fentanyl, by the year in which FDA received them and by species
YearDogCatHorseOther or not givenAll species
20261850023
20253490043
202431180150
20231470021
2022870015
20211330521
20201020113
20191030013
20182050025
20172320328
20165030760
20157610582
2014209408221
201393802103
201271008
201120002
200910001
200810001
200620002
200510001
200111002
199801001

2026 has the reports that FDA received through May 2026. Download the years (CSV)

What the reports record

Outcome at the time of the report

  • Recovered/Normal39.8%293
  • Recovered with Sequela[recovered, with a lasting effect]3.3%24
  • Ongoing11.3%83
  • Died9.6%71
  • Euthanized13.7%101
  • Outcome Unknown20.1%148

An outcome in a report is not proof that the drug caused it. The person who sends the report gives the outcome. Each share is of the 736 reports that name fentanyl.

A report about more than one animal can have more than one outcome.

Kind of report

  • Safety issue91%670
  • Lack of expected effectiveness2.2%16
  • Both safety and lack of expected effectiveness4.5%33
  • Manufacturing or product defect2.3%17
  • Other0%0

702 reports say if the event was serious. 48.7% of them have the serious flag. The person who sends the report sets the flag.

Show age, weight, breed and route

Age of the animal

  • Under 1 year5.3%39
  • 1 to 3 years17.8%131
  • 4 to 7 years25.5%188
  • 8 to 11 years24.9%183
  • 12 years and over7.5%55
  • Age not given19%140

Weight of the animal

  • Under 5 kg (11 lb)13.5%99
  • 5 to 9.9 kg (11 to 22 lb)17.1%126
  • 10 to 24.9 kg (22 to 55 lb)19.3%142
  • 25 to 44.9 kg (55 to 99 lb)25.5%188
  • 45 kg and over (99 lb and over)3.9%29
  • Weight not given20.7%152

Breed, where the report gives one breed

A breed with many animals has many reports.

Route in the report

  • Transdermal39.7%292
  • Topical21.2%156
  • Intravenous12%88
  • Other1.1%8
  • Cutaneous0.8%6
  • Intramuscular0.8%6

Each bar is on a scale of 0 to 100%.

Approved animal drugs with this active ingredient (FDA Green Book)

This section is reference data. It has no report count.

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand.

Applications in the Green Book of 2 Nov 2026, pioneer applications (NADA) first
Brand nameActive ingredientsSponsorApproved speciesApplication
Recuvyraapproval withdrawnFentanylElanco US Inc.DogsNADA 141-337

Other pages with this ingredient

A report names a drug by its set of active ingredients. Each set has its own page. The list is in order of name.

Next in the A to Z list

All drugs by active ingredient. Brand names A to Z

FDA pages for this drug

The site checked these addresses on . The links open in a new tab.

Cite this page

Pet Drug Reports. Fentanyl: adverse event reports that FDA received. https://petdrugreports.com/drug/fentanyl/ Source: FDA Center for Veterinary Medicine, openFDA Animal and Veterinary adverse event reports, export of . Reports received through .

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Where the data come from

The counts come from the openFDA Animal and Veterinary adverse event files, export of 30 Oct 2026. The files have the reports that the FDA Center for Veterinary Medicine received through 26 Jun 2026. The files mask brand and manufacturer names. The site counts a drug by the active ingredients that each record gives, and gives no count to a brand, an application or a company. Ingredient names and the lists of approved products follow the FDA Green Book of 2 Nov 2026. The site does not use the application number that a record has.

The site does not publish report text, lot numbers or details of a reporter. FDA's record is the authority. See how the site counts reports, the data sources and the corrections page.

Questions about these reports

Which brand are these reports about?

The openFDA records give the value "MSK" for the brand name and for the manufacturer name of each drug. FDA says that MSK means "masked". So the site cannot count a report for a brand. The Green Book lists no brand name for exactly this active ingredient.

Do the reports show that the drug caused the signs?

No. FDA states this about the data.

When looking at the results, be aware that there is no certainty that the reported drug or device caused the adverse event.

The adverse event may have been related to an underlying disease, other drugs used at the same time or other non-drug related sources.

FDA Center for Veterinary Medicine. Source: Adverse Event Reports for Animal Drugs and Devices

How many reports did FDA receive in the latest 12 months?

FDA received 45 reports in the 12 months to June 2026. It received 53 reports in the 12 months before. FDA says that a report can take 3 to 6 months to reach the public data. The newest months can get more reports in a later update.

What kinds of report are in the count?

Of the 736 reports received from December 1998 to May 2026, 91% are about a safety issue only. 6.7% are about a lack of expected effectiveness, alone or with a safety issue. 2.3% are about a defect of the product or its package.