Breed · Dog

King Charles Spaniel: adverse event reports

FDA breed label "Spaniel - King Charles" · 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.

470reports, 1994–20260.1% of dog reports

10reports, 12 months to March 202615 in the 12 months before

39.4%classed serious, as reportedall dogs: 38.3%

25.1%name milbemycin oxime + spinosadall dogs: 13.1%

FDA's database holds 470 reports where the animal's breed is given as "Spaniel - King Charles", shown here as King Charles Spaniel: 0.1% of reports about dogs. Reports on crossbred animals are left out of breed pages.

10 reports arrived in the 12 months to March 2026, down 33% from 15 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 milbemycin oxime + spinosad, ivermectin + pyrantel pamoate and afoxolaner. Milbemycin Oxime + Spinosad is named in 25.1% of this breed's reports, a larger share than in reports about all dogs (13.1%).

The terms listed most often are vomiting (21.9%), emesis (15.7%) and lethargy (15.5%). Vomiting appears in 21.9% of reports, about the same share as in all dog reports (19.7%). 39.4% 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 King Charles Spaniel reports	Share of all dog reports
Milbemycin Oxime + Spinosad	118	25.1%	13.1%
Ivermectin + Pyrantel Pamoate	83	17.7%	14.9%
Afoxolaner	69	14.7%	5.7%
Fluralaner	48	10.2%	6.7%
Spinosad	39	8.3%	5.8%
Pimobendan	18	3.8%	0.6%
Polysulfated Glycosaminoglycan	16	3.4%	0.4%
Trilostane	12	2.6%	1.2%
(S) - methoprene	9	1.9%	0.6%
Milbemycin Oxime + Praziquantel	8	1.7%	3.1%
Nitenpyram	8	1.7%	1.1%
Cyclosporine	7	1.5%	1.5%
Ivermectin	7	1.5%	1.3%
Carprofen	6	1.3%	4.8%
Enalapril Maleate	6	1.3%	0.2%
Lufenuron + Milbemycin Oxime	6	1.3%	2.7%
Milbemycin Oxime	6	1.3%	3%
Meloxicam	5	1.1%	0.8%
Benazepril	4	0.9%	0%
Cefpodoxime proxetil	4	0.9%	0.4%

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 King Charles Spaniel reports listing the termall dog reports

Vomiting21.9%103
Emesis[vomiting]15.7%74
Lethargy[unusually tired or inactive]15.5%73
Diarrhoea[diarrhea]12.6%59
Lack of efficacy (ectoparasite) - flea[the product did not have the expected effect: fleas]5.3%25
Seizure NOS[seizure, type not specified]5.3%25
Digestive tract disorder NOS[digestive problem, type not specified]5.1%24
Lack of efficacy - NOS[the product did not have the expected effect]5.1%24
Lack of efficacy (endoparasite) - hookworm[the product did not have the expected effect: hookworms]4.7%22
Not eating3.2%15
Ineffective, ascarids NOS[legacy FDA term: the product did not have the expected effect (ascarids nos)]3%14
Ineffective, hooks[legacy FDA term: the product did not have the expected effect (hooks)]3%14
Ataxia[unsteady, uncoordinated movement]2.6%12
Anorexia[not eating]2.3%11
Behavioural disorder NOS[behaviour change, type not specified]2.3%11
Death2.3%11
Pruritus[itching]2.1%10
Decreased appetite1.9%9
Emesis (multiple)[vomiting more than once]1.9%9
Itching1.9%9
Other abnormal test result NOS[abnormal laboratory result, type not specified]1.9%9
Twitching1.9%9
Panting1.7%8
Vocalisation[crying out or unusual noise]1.7%8
Hypersalivation[drooling]1.5%7

Age and weight

Age of the animal

Under 1 year14%66

1 to 3 years25.5%120

4 to 7 years29.8%140

8 to 11 years21.9%103

12 years and over5.1%24

Age not given3.6%17

Weight of the animal

Under 5 kg (11 lb)7.7%36

5 to 9.9 kg (11–22 lb)52.6%247

10 to 24.9 kg (22–55 lb)34.3%161

25 to 44.9 kg (55–99 lb)0.6%3

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

Weight not given4.9%23

Coloured bar: King Charles Spaniel 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/Normal47.9%225

Recovered with Sequela3.4%16

Ongoing10%47

Died2.6%12

Euthanized0.9%4

Outcome Unknown30.9%145

Beside all dogs

Measure	King Charles Spaniel	All dogs
Reports	470	985,675
Latest 12 months	10	53,292
Classed serious, of reports stating it	39.4%	38.3%
Death or euthanasia recorded, per 1,000 reports	34	55

Questions about King Charles Spaniel reports

How many FDA adverse event reports involve King Charles Spaniels?

470 reports through March 2026, 0.1% of reports about dogs; 10 in the latest 12 months.

Which drugs are named most often in King Charles Spaniel reports?

By active ingredient: milbemycin oxime + spinosad (118), ivermectin + pyrantel pamoate (83), afoxolaner (69), fluralaner (48) and spinosad (39). Brands are masked in the public data.

What signs are reported most for this breed?

vomiting (21.9%), emesis (15.7%), lethargy (15.5%), diarrhoea (12.6%) and lack of efficacy (ectoparasite) - flea (5.3%).

Is the King Charles Spaniel 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 King Charles Spaniel 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 ("Spaniel - King Charles" becomes "King Charles Spaniel"). 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.