December 2019: adverse event reports received

4,220 reports in the openFDA release of 28 Sep 2026

Read this first · FDA's caveat, in its words

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

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Not veterinary advice. This site lists what was reported to FDA. For an animal that is unwell, contact a veterinarian.

4,220reports received

4,241same month a year earlier0%

6,043monthly average, preceding 12 months

73.6%concern dogscats 9%

FDA's database holds 4,220 adverse event reports received in December 2019, against 4,241 in the same month a year earlier and a monthly average of 6,043 over the preceding 12 months.

73.6% of the month's reports concern dogs, 9% cats and 0.9% horses; the rest concern other species, exposed people, or give no species.

By active ingredient, the drugs named most often were ivermectin + pyrantel pamoate (689), moxidectin (403) and milbemycin oxime + spinosad (399), and the terms listed most often were vomiting (683), lack of efficacy (endoparasite) - heartworm (573) and lethargy (308). Report volume has a seasonal shape, with more reports in the warmer months when parasite products are in heavier use.

The months around it

Drugs named most often, by active ingredient

Active ingredients recorded for the drug	Reports	Share of the month's reports
Ivermectin + Pyrantel Pamoate	689	16.3%
Moxidectin	403	9.5%
Milbemycin Oxime + Spinosad	399	9.5%
Fluralaner	326	7.7%
Milbemycin Oxime + Praziquantel	294	7%
Afoxolaner	269	6.4%
Sarolaner	146	3.5%
Oclacitinib	104	2.5%
Lufenuron + Milbemycin Oxime	96	2.3%
Melarsomine Dihydrochloride	92	2.2%
Selamectin	87	2.1%
Carprofen	84	2%
Imidacloprid + Moxidectin	81	1.9%
Grapiprant	74	1.8%
Trilostane	72	1.7%

Ordered by report count, which follows how widely each drug was in use. 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 most often

Vomiting16.2%683
Lack of efficacy (endoparasite) - heartworm[the product did not have the expected effect: heartworm]13.6%573
Lethargy[unusually tired or inactive]7.3%308
Ineffective, hooks[legacy FDA term: the product did not have the expected effect (hooks)]5.5%231
Diarrhoea[diarrhea]4.5%188
Death3.3%140
Seizure NOS[seizure, type not specified]3.1%130
Unpalatable[legacy FDA term: the animal would not take it]3%128
Lack of efficacy - NOS[the product did not have the expected effect]2.9%123
Product problem[a product quality report, not a sign in an animal]2.6%108
Lack of efficacy (endoparasite) - roundworm NOS[the product did not have the expected effect: roundworms]2.4%103
Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]2.2%94
Ataxia[unsteady, uncoordinated movement]2.1%89
Hives2%85
Facial swelling2%83

Single ingredients, pooled

Milbemycin Oxime20.4%859

Pyrantel Pamoate18.5%781

Ivermectin17.8%751

Moxidectin11.5%486

Praziquantel11.2%474

Spinosad10.9%460

Fluralaner7.7%327

Afoxolaner6.4%269

Sarolaner5.1%217

Selamectin3.6%154

Lufenuron3.6%151

Oclacitinib2.5%104

Species

Dog73.6%3,104

Cat9%379

Horse0.9%36

Other or not given16.6%701

Questions about December 2019

How many animal drug adverse event reports did FDA receive in December 2019?

4,220 reports are in the openFDA release of 28 Sep 2026. The same month a year earlier has 4,241.

Which drugs were named most often?

By active ingredient: ivermectin + pyrantel pamoate (689), moxidectin (403), milbemycin oxime + spinosad (399), fluralaner (326) and milbemycin oxime + praziquantel (294). Brands are masked in the public data.

Which signs were listed most often?

vomiting (683), lack of efficacy (endoparasite) - heartworm (573), lethargy (308), ineffective, hooks (231) and diarrhoea (188).

Can the count for a month still change?

Yes. FDA posts reports quarterly with a delay of three to six months, so the newest months are incomplete and usually grow in later releases. Older months change little.

Does a busy month mean something went wrong that month?

Not by itself. The date is when FDA received the report, not when the event happened, and volume follows season, product launches and publicity. 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."

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. The month is the date FDA first received the report, not the date of the event. 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.