Breed · Dog
Bullmastiff: adverse event reports
FDA breed label "Bullmastiff" · single-breed animals only
FDA's database holds 619 reports where the animal's breed is given as "Bullmastiff", shown here as Bullmastiff: 0.1% of reports about dogs. Reports on crossbred animals are left out of breed pages.
26 reports arrived in the 12 months to March 2026, close to the 24 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 ivermectin + pyrantel pamoate, milbemycin oxime + spinosad and carprofen. Ivermectin + Pyrantel Pamoate is named in 15% of this breed's reports, about the same share as in reports about all dogs (14.9%).
The terms listed most often are vomiting (21.8%), ineffective, heartworm larvae (9.5%) and diarrhoea (9.2%). Vomiting appears in 21.8% of reports, about the same share as in all dog reports (19.7%). 34.6% 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 Bullmastiff reports | Share of all dog reports |
|---|---|---|---|
| Ivermectin + Pyrantel Pamoate | 93 | 15% | 14.9% |
| Milbemycin Oxime + Spinosad | 92 | 14.9% | 13.1% |
| Carprofen | 49 | 7.9% | 4.8% |
| Spinosad | 34 | 5.5% | 5.8% |
| Oclacitinib | 28 | 4.5% | 2.9% |
| Fluralaner | 26 | 4.2% | 6.7% |
| Milbemycin Oxime + Praziquantel | 25 | 4% | 3.1% |
| Moxidectin | 24 | 3.9% | 5% |
| Afoxolaner | 23 | 3.7% | 5.7% |
| Milbemycin Oxime | 20 | 3.2% | 3% |
| Pyrantel Pamoate + Sarolaner | 20 | 3.2% | 5.1% |
| Selamectin | 19 | 3.1% | 3% |
| Melarsomine Dihydrochloride | 18 | 2.9% | 2.3% |
| Lufenuron + Milbemycin Oxime | 16 | 2.6% | 2.7% |
| Bedinvetmab | 13 | 2.1% | 1.9% |
| Deracoxib | 12 | 1.9% | 1.1% |
| Gabapentin | 11 | 1.8% | 0.9% |
| Pyrantel Pamoate | 11 | 1.8% | 0.5% |
| Grapiprant | 9 | 1.5% | 0.8% |
| Meloxicam | 9 | 1.5% | 0.8% |
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 Bullmastiff reports listing the termall dog reports
- Vomiting21.8%135
- Ineffective, heartworm larvae[legacy FDA term: the product did not have the expected effect (heartworm larvae)]9.5%59
- Diarrhoea[diarrhea]9.2%57
- Emesis[vomiting]8.1%50
- Anorexia[not eating]7.8%48
- Lethargy[unusually tired or inactive]6.9%43
- Depression[dull, quiet or withdrawn]6.6%41
- Lack of efficacy (endoparasite) - heartworm[the product did not have the expected effect: heartworm]5.2%32
- Death by euthanasia[the animal was euthanized]3.9%24
- Digestive tract disorder NOS[digestive problem, type not specified]3.7%23
- Lack of efficacy (endoparasite) - hookworm[the product did not have the expected effect: hookworms]3.7%23
- Lack of efficacy - NOS[the product did not have the expected effect]3.6%22
- Death3.4%21
- Weight loss3.4%21
- Ineffective, ascarids NOS[legacy FDA term: the product did not have the expected effect (ascarids nos)]3.1%19
- Seizure NOS[seizure, type not specified]2.9%18
- Underdose[less than the labelled amount was given]2.9%18
- Ataxia[unsteady, uncoordinated movement]2.6%16
- Bloody diarrhoea[diarrhea with blood]2.6%16
- Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]2.6%16
- Not eating2.6%16
- Fever2.3%14
- Anaemia NOS[low red blood cell count]2.1%13
- Elevated serum alkaline phosphatase (SAP)[a liver and bone enzyme above the normal range]2.1%13
- Elevated creatinine[a kidney value above the normal range]1.9%12
Age and weight
Age of the animal
Weight of the animal
Coloured bar: Bullmastiff 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
Beside all dogs
| Measure | Bullmastiff | All dogs |
|---|---|---|
| Reports | 619 | 985,675 |
| Latest 12 months | 26 | 53,292 |
| Classed serious, of reports stating it | 34.6% | 38.3% |
| Death or euthanasia recorded, per 1,000 reports | 77.5 | 55 |
Questions about Bullmastiff reports
How many FDA adverse event reports involve Bullmastiffs?
619 reports through March 2026, 0.1% of reports about dogs; 26 in the latest 12 months.
Which drugs are named most often in Bullmastiff reports?
By active ingredient: ivermectin + pyrantel pamoate (93), milbemycin oxime + spinosad (92), carprofen (49), spinosad (34) and oclacitinib (28). Brands are masked in the public data.
What signs are reported most for this breed?
vomiting (21.8%), ineffective, heartworm larvae (9.5%), diarrhoea (9.2%), emesis (8.1%) and anorexia (7.8%).
Is the Bullmastiff 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 Bullmastiff 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 ("Bullmastiff" becomes "Bullmastiff"). 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.