Loss of appetite after Ivermectin + Pyrantel (Heartgard Plus) in dogs

4,658 reports to the FDA describe loss of appetite in dogs given Ivermectin + Pyrantel. That is 3.2% of all reports for this medicine, compared with 8.4% across reports for all dog medicines, so it is reported less often than average with this medicine.

4,658Reports
46%Marked serious
26%Recovered
8.3%Died or euthanised
3 daysTypical onset
SponsoredWorried about your pet? Ask a veterinarian online, 24/7

How soon it started

Same day
697 27%
1–2 days
574 23%
3–7 days
206 8.1%
1–4 weeks
333 13%
Over a month
735 29%

How the animals did

Recovered
1,188 26%
Recovered with lasting effects
44 0.9%
Still unwell when reported
512 11%
Died
197 4.2%
Euthanised
189 4.1%
Not known
2,528 54%

Problems reported at the same time

2,400 52%
2,079 45%
1,340 29%
382 8.2%
375 8.1%

Age of the animals

Under 1 year
665
1–3 years
1,278
4–7 years
1,233
8–11 years
886
12+ years
469

About this medicine

Ivermectin prevents heartworm disease (monthly). Pyrantel treats roundworms and hookworms.

Products with this combination include Heartgard Plus, Tri-Heart Plus, Iverhart Plus. 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 + Pyrantel cause loss of appetite in dogs?
4,658 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 3 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 + Pyrantel in dogs · Medicines most reported with loss of appetite