Breed · Dog

Boston Terrier: adverse event reports

FDA breed label "Terrier - Boston" · 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.

8,505reports, 1987–20260.9% of dog reports

367reports, 12 months to March 2026358 in the 12 months before

40.7%classed serious, as reportedall dogs: 38.3%

16.3%name milbemycin oxime + spinosadall dogs: 13.1%

FDA's database holds 8,505 reports where the animal's breed is given as "Terrier - Boston", shown here as Boston Terrier: 0.9% of reports about dogs. Reports on crossbred animals are left out of breed pages.

367 reports arrived in the 12 months to March 2026, close to the 358 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, ivermectin + pyrantel pamoate and spinosad. Milbemycin Oxime + Spinosad is named in 16.3% of this breed's reports, about the same share as in reports about all dogs (13.1%).

The terms listed most often are vomiting (21.3%), emesis (9%) and lethargy (8.4%). Vomiting appears in 21.3% of reports, about the same share as in all dog reports (19.7%). 40.7% 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 Boston Terrier reports	Share of all dog reports
Milbemycin Oxime + Spinosad	1,386	16.3%	13.1%
Ivermectin + Pyrantel Pamoate	1,063	12.5%	14.9%
Spinosad	569	6.7%	5.8%
Trilostane	495	5.8%	1.2%
Moxidectin	491	5.8%	5%
Fluralaner	478	5.6%	6.7%
Oclacitinib	367	4.3%	2.9%
Afoxolaner	340	4%	5.7%
Pyrantel Pamoate + Sarolaner	319	3.8%	5.1%
Cyclosporine	251	3%	1.5%
Lufenuron + Milbemycin Oxime	246	2.9%	2.7%
Carprofen	244	2.9%	4.8%
Selamectin	241	2.8%	3%
Milbemycin Oxime	232	2.7%	3%
Milbemycin Oxime + Praziquantel	195	2.3%	3.1%
Maropitant	131	1.5%	1.2%
Melarsomine Dihydrochloride	128	1.5%	2.3%
Sarolaner	122	1.4%	1.7%
Imidacloprid + Moxidectin	115	1.4%	1.3%
Ivermectin	106	1.2%	1.3%

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 Boston Terrier reports listing the termall dog reports

Vomiting21.3%1,809
Emesis[vomiting]9%765
Lethargy[unusually tired or inactive]8.4%717
Diarrhoea[diarrhea]7.7%657
Lack of efficacy (endoparasite) - hookworm[the product did not have the expected effect: hookworms]5.5%464
Ineffective, heartworm larvae[legacy FDA term: the product did not have the expected effect (heartworm larvae)]5%427
Lack of efficacy - NOS[the product did not have the expected effect]4.5%383
Seizure NOS[seizure, type not specified]4.2%357
Anorexia[not eating]4%343
Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]3.7%317
Depression[dull, quiet or withdrawn]3.4%292
Elevated alanine aminotransferase (ALT)[a liver enzyme above the normal range]3.1%260
Death2.6%223
Lack of efficacy (endoparasite) - heartworm[the product did not have the expected effect: heartworm]2.6%220
Hives2.5%213
Ataxia[unsteady, uncoordinated movement]2.4%207
Elevated serum alkaline phosphatase (SAP)[a liver and bone enzyme above the normal range]2.4%204
Death by euthanasia[the animal was euthanized]2.4%200
Other abnormal test result NOS[abnormal laboratory result, type not specified]2.3%196
Weight loss2.2%189
Digestive tract disorder NOS[digestive problem, type not specified]2.2%188
Facial swelling2.1%176
Ineffective, ascarids NOS[legacy FDA term: the product did not have the expected effect (ascarids nos)]2.1%176
Behavioural disorder NOS[behaviour change, type not specified]2%173
Pruritus[itching]2%169

Age and weight

Age of the animal

Under 1 year11.1%946

1 to 3 years27.7%2,356

4 to 7 years25.8%2,196

8 to 11 years23.3%1,979

12 years and over9.3%787

Age not given2.8%241

Weight of the animal

Under 5 kg (11 lb)4.9%420

5 to 9.9 kg (11–22 lb)47.6%4,050

10 to 24.9 kg (22–55 lb)43.6%3,707

25 to 44.9 kg (55–99 lb)0.1%10

45 kg and over (99 lb+)0%1

Weight not given3.7%317

Coloured bar: Boston 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/Normal28.5%2,423

Recovered with Sequela2.9%248

Ongoing18.4%1,561

Died3.4%289

Euthanized1.8%151

Outcome Unknown23.5%1,997

Beside all dogs

Measure	Boston Terrier	All dogs
Reports	8,505	985,675
Latest 12 months	367	53,292
Classed serious, of reports stating it	40.7%	38.3%
Death or euthanasia recorded, per 1,000 reports	51.7	55

Questions about Boston Terrier reports

How many FDA adverse event reports involve Boston Terriers?

8,505 reports through March 2026, 0.9% of reports about dogs; 367 in the latest 12 months.

Which drugs are named most often in Boston Terrier reports?

By active ingredient: milbemycin oxime + spinosad (1,386), ivermectin + pyrantel pamoate (1,063), spinosad (569), trilostane (495) and moxidectin (491). Brands are masked in the public data.

What signs are reported most for this breed?

vomiting (21.3%), emesis (9%), lethargy (8.4%), diarrhoea (7.7%) and lack of efficacy (endoparasite) - hookworm (5.5%).

Is the Boston 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 Boston 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 1 Oct 2026. Breed names are FDA's labels rearranged into everyday order ("Terrier - Boston" becomes "Boston 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.