Drug profile

The FDA adverse-event record for Doxycycline

3,706 adverse-event reports submitted to the FDA Center for Veterinary Medicine reference Doxycycline. See the species affected, top reactions, and outcomes below.

3,706
adverse-event reports
14.3%
death-coded share
Dog
most-reported species
1,098
Lack of efficacy (endoparasite) - heartworm - top reaction
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Important: Adverse event reports do not establish that a drug caused or contributed to the event. Consult your veterinarian before making treatment decisions.
3,706
Total Reports
530
Deaths Reported
14.3%
Death Rate

Active Ingredients

Doxycycline

Administration Routes

OralUnknownIntravenousTopicalSubcutaneousPeriodontalIntramuscularAuricular (Otic)OphthalmicParenteral

Species Affected

Dog 3,469
Cat 207
Unknown 15
Horse 14
Human 1

Most Affected Breeds

Retriever - Labrador 470
Crossbred Canine/dog 193
Shepherd Dog - German 190
Beagle 165
Terrier - Bull - American Pit 150
Chihuahua 146
Retriever - Golden 126
Domestic Shorthair 122
Dog (unknown) 104
Terrier (unspecified) 100

Most Reported Reactions

Lack of efficacy (endoparasite) - heartworm 1,098
Vomiting 552
Lethargy (see also Central nervous system depression in 'Neurological') 458
Other abnormal test result NOS 340
Death by euthanasia 297
Anorexia 288
Elevated alanine aminotransferase (ALT) 252
Diarrhoea 249
Lack of efficacy - NOS 238
Death 220
Cough 211
Leucocytosis NOS 208

Outcome Breakdown

Ongoing
1,773 (48.1%)
Outcome Unknown
822 (22.3%)
Recovered/Normal
533 (14.5%)
Euthanized
291 (7.9%)
Died
240 (6.5%)
Recovered with Sequela
27 (0.7%)

Doxycycline Adverse Event Insights

3,706 reports name Doxycycline; 530 recorded a death outcome (14.3% of reported events, not a population-level mortality rate). Active ingredient: Doxycycline. Administration routes: Oral, Unknown, Intravenous, Topical.

By species: Dog (3,469 reports), Cat (207 reports), Unknown (15 reports). By breed: Retriever - Labrador (470), Crossbred Canine/dog (193), Shepherd Dog - German (190).

Leading clinical signs: Lack of efficacy (endoparasite) - heartworm (1,098), Vomiting (552), Lethargy (see also Central nervous system depression in 'Neurological') (458), Other abnormal test result NOS (340). Outcome, 3,686 coded reports: Ongoing leads at 48.1%.

Read these counts as reporting volume, not risk: per our methodology, a widely-prescribed drug will rack up more raw FDA reports in a given year than a rarely-used one at an identical true rate, so we recommend comparing within similar-exposure products rather than across the full 2025 catalog.

Source: FDA Center for Veterinary Medicine openFDA Animal & Veterinary Adverse Events (CVM AER) · 2025

Every figure on PlainBreed is rendered directly from FDA openFDA adverse event data, no number is typed in by an editor. This page draws directly on FDA openFDA data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.