Decreased packed cell volume (pcv) after Ivermectin + Pyrantel (Heartgard Plus) in dogs

The FDA has received 100 reports of decreased packed cell volume (pcv) in dogs after Ivermectin + Pyrantel. That is 0.1% of all reports for this medicine, compared with 0.1% across reports for all dog medicines, so it is reported less often than average with this medicine.

100Reports

77%Marked serious

11%Recovered

18%Died or euthanised

8 daysTypical onset

How soon it started

Same day

10 20%

1–2 days

8 16%

3–7 days

7 14%

1–4 weeks

13 25%

Over a month

13 25%

How the animals did

Recovered

10 10%

Recovered with lasting effects

1 1.0%

Still unwell when reported

36 36%

Died

3 3.0%

Euthanised

15 15%

Not known

35 35%

Problems reported at the same time

50 50%

49 49%

44 44%

42 42%

29 29%

Decreased red blood cell count

29 29%

Diarrhea

28 28%

Vomiting

28 28%

Age of the animals

Under 1 year

1–3 years

4–7 years

8–11 years

12+ years

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 decreased packed cell volume (pcv) in dogs?: 100 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 8 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).

Decreased packed cell volume (pcv) with similar medicines

Decreased packed cell volume (pcv) after Milbemycin Oxime + Spinosad (Trifexis) 40 reports · 0.0% of its reports
Decreased packed cell volume (pcv) after Moxidectin (ProHeart 6) 76 reports · 0.2% of its reports
Decreased packed cell volume (pcv) after Milbemycin Oxime + Praziquantel (Interceptor Plus) 25 reports · 0.1% of its reports
Decreased packed cell volume (pcv) after Ivermectin (Heartgard) 24 reports · 0.2% of its reports

All reported side effects of Ivermectin + Pyrantel in dogs · Medicines most reported with decreased packed cell volume (pcv)