Cardiac enlargement after Doxycycline in dogs

33 reports to the FDA describe cardiac enlargement in dogs given Doxycycline. That is 0.8% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported unusually often with this medicine.

33Reports

94%Marked serious

0.0%Recovered

42%Died or euthanised

28 daysTypical onset

How soon it started

Same day

3 14%

1–2 days

0 0.0%

3–7 days

4 18%

1–4 weeks

5 23%

Over a month

10 45%

How the animals did

Still unwell when reported

13 39%

Died

6 18%

Euthanised

8 24%

Not known

6 18%

Problems reported at the same time

Abnormal radiograph finding

23 70%

15 45%

14 42%

13 39%

10 30%

8 24%

8 24%

Didn't prevent heartworm

8 24%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

About this medicine

Doxycycline treats bacterial and tick-borne infections.

Questions owners ask

Can Doxycycline cause cardiac enlargement in dogs?: 33 reports link the two, but a report alone does not prove the medicine was the cause: other illnesses, other medicines or coincidence can be involved. Your vet can judge it for your animal.
How soon after a dose was it reported?: In half of the reports with dates, it started within 28 days of the first dose.
What should I do?: Don't give another dose until you've spoken to your vet, and keep the packaging so you can tell them the product and dose. Your vet can also report it to the FDA (or you can, through the manufacturer or FDA form 1932a).

Cardiac enlargement with similar medicines

Cardiac enlargement after Amoxicillin + Clavulanate (Clavamox) 23 reports · 0.4% of its reports
Cardiac enlargement after Cefovecin (Convenia) 21 reports · 0.6% of its reports

All reported side effects of Doxycycline in dogs · Medicines most reported with cardiac enlargement