Lymphoma after Moxidectin (ProHeart 6) in dogs

The FDA has received 51 reports of lymphoma in dogs after Moxidectin. That is 0.1% of all reports for this medicine, compared with 0.1% across reports for all dog medicines.

51Reports
35%Marked serious
0.0%Recovered
51%Died or euthanised
66 daysTypical onset
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How soon it started

Same day
1 5.9%
1–2 days
1 5.9%
3–7 days
3 18%
1–4 weeks
1 5.9%
Over a month
11 65%

How the animals did

Still unwell when reported
12 24%
Died
18 35%
Euthanised
8 16%
Not known
13 25%

Problems reported at the same time

Death
25 49%
Lymphadenopathy
22 43%
Pr-lymph node(s), lesion(s)
18 35%
Loss of appetite
15 29%
Liver problems
14 27%
Lethargy
13 25%
Vomiting
9 18%
Weight loss
8 16%

Age of the animals

Under 1 year
0
1–3 years
9
4–7 years
21
8–11 years
18
12+ years
3

About this medicine

Moxidectin prevents heartworm disease (monthly topical, or a 6- or 12-month injection for dogs).

Products with this ingredient include ProHeart 6, ProHeart 12. 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 Moxidectin cause lymphoma in dogs?
51 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 66 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).

Lymphoma with similar medicines

All reported side effects of Moxidectin in dogs · Medicines most reported with lymphoma