Breed · Dog

Yorkshire Terrier: adverse event reports

FDA breed label "Terrier - Yorkshire" · single-breed animals only

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.

24,199reports, 1987–20262.5% of dog reports

881reports, 12 months to March 2026961 in the 12 months before

35.6%classed serious, as reportedall dogs: 38.3%

17.4%name milbemycin oxime + spinosadall dogs: 13.1%

24,199 adverse event reports received by FDA describe an animal recorded as Yorkshire Terrier (FDA breed label "Terrier - Yorkshire"). That is 2.5% of all reports about dogs. Crossbred animals are not counted here, only reports that give this single breed.

881 reports arrived in the 12 months to March 2026, close to the 961 of the 12 months before. A breed's count mostly mirrors how common the breed is; registration and ownership figures by breed are not public data, so no per-animal rate can be given.

By active ingredient, the drugs named most often are milbemycin oxime + spinosad, spinosad and ivermectin + pyrantel pamoate. Milbemycin Oxime + Spinosad is named in 17.4% of this breed's reports, a larger share than in reports about all dogs (13.1%).

The terms listed most often are vomiting (26.1%), lethargy (11.5%) and emesis (9.8%). Vomiting appears in 26.1% of reports, a larger share than in all dog reports (19.7%). 35.6% of reports stating seriousness were classed as serious, against 38.3% for dogs overall.

Drugs named most often, by active ingredient

Active ingredients recorded for the drug	Reports	Share of Yorkshire Terrier reports	Share of all dog reports
Milbemycin Oxime + Spinosad	4,219	17.4%	13.1%
Spinosad	2,760	11.4%	5.8%
Ivermectin + Pyrantel Pamoate	2,061	8.5%	14.9%
Fluralaner	1,845	7.6%	6.7%
Afoxolaner	1,520	6.3%	5.7%
Moxidectin	1,109	4.6%	5%
Selamectin	925	3.8%	3%
Pyrantel Pamoate + Sarolaner	851	3.5%	5.1%
Oclacitinib	791	3.3%	2.9%
Sarolaner	618	2.6%	1.7%
Lufenuron + Milbemycin Oxime	613	2.5%	2.7%
Imidacloprid + Moxidectin	604	2.5%	1.3%
Milbemycin Oxime	540	2.2%	3%
Cyclosporine	464	1.9%	1.5%
Carprofen	433	1.8%	4.8%
Nitenpyram	420	1.7%	1.1%
Milbemycin Oxime + Praziquantel	417	1.7%	3.1%
Maropitant	397	1.6%	1.2%
Meloxicam	350	1.4%	0.8%
Ivermectin + Praziquantel + Pyrantel Pamoate	345	1.4%	0.9%

Ordered by report count. Differences from the species column often come from body size (which drugs a breed is prescribed) and from how common the breed was in the years a drug sold most. 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 in reports

share of Yorkshire Terrier reports listing the termall dog reports

Vomiting26.1%6,304
Lethargy[unusually tired or inactive]11.5%2,793
Emesis[vomiting]9.8%2,377
Diarrhoea[diarrhea]9.6%2,328
Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]8.9%2,147
Anorexia[not eating]4.9%1,182
Depression[dull, quiet or withdrawn]4.3%1,031
Seizure NOS[seizure, type not specified]3.9%940
Lack of efficacy - NOS[the product did not have the expected effect]3.8%912
Ataxia[unsteady, uncoordinated movement]3.6%865
Shaking3.2%764
Pruritus[itching]3%730
Behavioural disorder NOS[behaviour change, type not specified]2.9%695
Death2.5%615
Bloody diarrhoea[diarrhea with blood]2.4%587
Trembling2.4%586
Emesis (multiple)[vomiting more than once]2.4%585
Not eating2.4%579
Accidental exposure[exposure that was not intended]2.3%548
Lack of efficacy (endoparasite) - hookworm[the product did not have the expected effect: hookworms]2.2%533
Overdose[more than the labelled amount was given]2.1%499
Other abnormal test result NOS[abnormal laboratory result, type not specified]2%475
Elevated blood urea nitrogen (BUN)[a kidney value above the normal range]1.9%464
Tremor1.8%429
Decreased appetite1.7%413

Age and weight

Age of the animal

Under 1 year11.2%2,706

1 to 3 years27%6,526

4 to 7 years26%6,289

8 to 11 years19.8%4,792

12 years and over11.5%2,776

Age not given4.6%1,110

Weight of the animal

Under 5 kg (11 lb)74.8%18,097

5 to 9.9 kg (11–22 lb)21%5,091

10 to 24.9 kg (22–55 lb)0.6%146

25 to 44.9 kg (55–99 lb)0%4

45 kg and over (99 lb+)0%0

Weight not given3.6%861

Coloured bar: Yorkshire Terrier reports. Grey bar: all dog reports.

Trend and outcomes

Reports by month FDA received them. The newest months are incomplete because FDA posts reports with a delay of three to six months.

Outcome recorded in the report

Recovered/Normal32.5%7,858

Recovered with Sequela2.7%646

Ongoing17.7%4,295

Died3.2%768

Euthanized1.3%313

Outcome Unknown23.4%5,671

Beside all dogs

Measure	Yorkshire Terrier	All dogs
Reports	24,199	985,675
Latest 12 months	881	53,292
Classed serious, of reports stating it	35.6%	38.3%
Death or euthanasia recorded, per 1,000 reports	44.7	55

Questions about Yorkshire Terrier reports

How many FDA adverse event reports involve Yorkshire Terriers?

24,199 reports through March 2026, 2.5% of reports about dogs; 881 in the latest 12 months.

Which drugs are named most often in Yorkshire Terrier reports?

By active ingredient: milbemycin oxime + spinosad (4,219), spinosad (2,760), ivermectin + pyrantel pamoate (2,061), fluralaner (1,845) and afoxolaner (1,520). Brands are masked in the public data.

What signs are reported most for this breed?

vomiting (26.1%), lethargy (11.5%), emesis (9.8%), diarrhoea (9.6%) and lack of efficacy (ectoparasite) - flea (8.9%).

Is the Yorkshire Terrier more sensitive to certain drugs?

Report counts cannot answer that. They show what was reported, not what a drug did, and they are not adjusted for how many Yorkshire Terrier animals exist or were treated. Breed-related drug sensitivities that are established are described on FDA-approved labels; a veterinarian is the person to ask about an individual animal.

Why are crossbreds not included?

FDA records crossbred animals with one or more component breeds. Counting them under each component would double count, so breed pages use single-breed reports only. Crossbreds remain in the species totals.

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. Breed names are FDA's labels rearranged into everyday order ("Terrier - Yorkshire" becomes "Yorkshire Terrier"). 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.