Didn't prevent heartworm after Prednisone in dogs

The FDA has received 600 reports of didn't prevent heartworm in dogs after Prednisone. That is 6.7% of all reports for this medicine, compared with 13% across reports for all dog medicines, so it is reported less often than average with this medicine.

600Reports
55%Marked serious
2.7%Recovered
1.8%Died or euthanised
189 daysTypical onset
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How soon it started

Same day
9 2.5%
1–2 days
1 0.3%
3–7 days
1 0.3%
1–4 weeks
20 5.5%
Over a month
334 92%

How the animals did

Recovered
13 2.2%
Recovered with lasting effects
3 0.5%
Still unwell when reported
344 57%
Died
7 1.2%
Euthanised
4 0.7%
Not known
229 38%

Problems reported at the same time

Didn't work as expected
46 7.7%
Vomiting
31 5.2%
Diarrhea
27 4.5%
Weight loss
27 4.5%
Weight gain
26 4.3%
Liver problems
22 3.7%
Cough
21 3.5%
Medication error
21 3.5%

Age of the animals

Under 1 year
7
1–3 years
308
4–7 years
193
8–11 years
72
12+ years
6

About this medicine

Prednisone reduces inflammation and immune activity.

Steroids commonly cause increased thirst, urination and appetite, especially at higher doses.

Questions owners ask

Can Prednisone cause didn't prevent heartworm in dogs?
600 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 189 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).

Didn't prevent heartworm with similar medicines

All reported side effects of Prednisone in dogs · Medicines most reported with didn't prevent heartworm