Breed · Dog

Bull Terrier: adverse event reports

FDA breed label "Terrier - Bull" · 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.

1,112reports, 1987–20260.1% of dog reports

62reports, 12 months to March 202696 in the 12 months before

38.5%classed serious, as reportedall dogs: 38.3%

13.7%name ivermectin + pyrantel pamoateall dogs: 14.9%

FDA's database holds 1,112 reports where the animal's breed is given as "Terrier - Bull", shown here as Bull Terrier: 0.1% of reports about dogs. Reports on crossbred animals are left out of breed pages.

62 reports arrived in the 12 months to March 2026, down 35% from 96 in 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 ivermectin + pyrantel pamoate, milbemycin oxime + spinosad and oclacitinib. Ivermectin + Pyrantel Pamoate is named in 13.7% of this breed's reports, about the same share as in reports about all dogs (14.9%).

The terms listed most often are vomiting (19.1%), lethargy (9%) and diarrhoea (8.8%). Vomiting appears in 19.1% of reports, about the same share as in all dog reports (19.7%). 38.5% 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 Bull Terrier reports	Share of all dog reports
Ivermectin + Pyrantel Pamoate	152	13.7%	14.9%
Milbemycin Oxime + Spinosad	113	10.2%	13.1%
Oclacitinib	106	9.5%	2.9%
Spinosad	56	5%	5.8%
Afoxolaner	55	4.9%	5.7%
Fluralaner	54	4.9%	6.7%
Moxidectin	53	4.8%	5%
Bedinvetmab	44	4%	1.9%
Pyrantel Pamoate + Sarolaner	44	4%	5.1%
Cyclosporine	43	3.9%	1.5%
Melarsomine Dihydrochloride	41	3.7%	2.3%
Carprofen	39	3.5%	4.8%
Gabapentin	32	2.9%	0.9%
Ivermectin	28	2.5%	1.3%
Selamectin	28	2.5%	3%
Lufenuron + Milbemycin Oxime	27	2.4%	2.7%
Milbemycin Oxime + Praziquantel	25	2.2%	3.1%
Prednisone	19	1.7%	0.9%
Deracoxib	18	1.6%	1.1%
Milbemycin Oxime	18	1.6%	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 Bull Terrier reports listing the termall dog reports

Vomiting19.1%212
Lethargy[unusually tired or inactive]9%100
Diarrhoea[diarrhea]8.8%98
Ineffective, heartworm larvae[legacy FDA term: the product did not have the expected effect (heartworm larvae)]6.8%76
Lack of efficacy (endoparasite) - heartworm[the product did not have the expected effect: heartworm]6.3%70
Anorexia[not eating]6%67
Depression[dull, quiet or withdrawn]5.7%63
Lack of efficacy - NOS[the product did not have the expected effect]5.4%60
Emesis[vomiting]4.6%51
Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]4.4%49
Lack of efficacy (endoparasite) - hookworm[the product did not have the expected effect: hookworms]4%45
Ataxia[unsteady, uncoordinated movement]3.4%38
Behavioural disorder NOS[behaviour change, type not specified]3.1%34
Panting3%33
Other abnormal test result NOS[abnormal laboratory result, type not specified]2.8%31
Death2.5%28
Weight loss2.2%25
Death by euthanasia[the animal was euthanized]2.1%23
Urticaria[hives]2.1%23
Anaemia NOS[low red blood cell count]2%22
Bloody diarrhoea[diarrhea with blood]2%22
Not eating1.9%21
Digestive tract disorder NOS[digestive problem, type not specified]1.8%20
Elevated blood urea nitrogen (BUN)[a kidney value above the normal range]1.8%20
Elevated serum alkaline phosphatase (SAP)[a liver and bone enzyme above the normal range]1.8%20

Age and weight

Age of the animal

Under 1 year12.6%140

1 to 3 years33.5%373

4 to 7 years25.8%287

8 to 11 years17%189

12 years and over7.9%88

Age not given3.1%35

Weight of the animal

Under 5 kg (11 lb)1.4%16

5 to 9.9 kg (11–22 lb)2.5%28

10 to 24.9 kg (22–55 lb)53.9%599

25 to 44.9 kg (55–99 lb)37.4%416

45 kg and over (99 lb+)0.7%8

Weight not given4%45

Coloured bar: Bull 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/Normal20.1%223

Recovered with Sequela4%44

Ongoing24.4%271

Died3.2%36

Euthanized1.6%18

Outcome Unknown22.7%252

Beside all dogs

Measure	Bull Terrier	All dogs
Reports	1,112	985,675
Latest 12 months	62	53,292
Classed serious, of reports stating it	38.5%	38.3%
Death or euthanasia recorded, per 1,000 reports	48.6	55

Questions about Bull Terrier reports

How many FDA adverse event reports involve Bull Terriers?

1,112 reports through March 2026, 0.1% of reports about dogs; 62 in the latest 12 months.

Which drugs are named most often in Bull Terrier reports?

By active ingredient: ivermectin + pyrantel pamoate (152), milbemycin oxime + spinosad (113), oclacitinib (106), spinosad (56) and afoxolaner (55). Brands are masked in the public data.

What signs are reported most for this breed?

vomiting (19.1%), lethargy (9%), diarrhoea (8.8%), ineffective, heartworm larvae (6.8%) and lack of efficacy (endoparasite) - heartworm (6.3%).

Is the Bull 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 Bull 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 - Bull" becomes "Bull 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.