Loss of appetite after Ivermectin (Heartgard) in dogs

806 reports to the FDA describe loss of appetite in dogs given Ivermectin. That is 6.7% of all reports for this medicine, compared with 8.4% across reports for all dog medicines.

806Reports
38%Marked serious
29%Recovered
14%Died or euthanised
24 daysTypical onset
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How soon it started

Same day
71 15%
1–2 days
66 14%
3–7 days
39 8.0%
1–4 weeks
85 17%
Over a month
227 47%

How the animals did

Recovered
200 25%
Recovered with lasting effects
36 4.5%
Still unwell when reported
196 24%
Died
44 5.5%
Euthanised
65 8.1%
Not known
265 33%

Problems reported at the same time

Age of the animals

Under 1 year
107
1–3 years
198
4–7 years
197
8–11 years
190
12+ years
93

About this medicine

Ivermectin prevents heartworm disease (monthly).

Products with this ingredient include Heartgard. The FDA hides brand names in its public data, so these reports cover every product with the same active ingredients.

Some herding breeds (for example Collies) carry the MDR1 gene variant and can be more sensitive to this drug class at high doses.

Questions owners ask

Can Ivermectin cause loss of appetite in dogs?
806 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 24 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).

Loss of appetite with similar medicines

All reported side effects of Ivermectin in dogs · Medicines most reported with loss of appetite