Elevated gamma-glutamyl transferase (ggt) after Moxidectin (ProHeart 6) in dogs

The FDA has received 147 reports of elevated gamma-glutamyl transferase (ggt) in dogs after Moxidectin. That is 0.3% of all reports for this medicine, compared with 0.4% across reports for all dog medicines.

147Reports
45%Marked serious
6.1%Recovered
22%Died or euthanised
2 daysTypical onset
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How soon it started

Same day
34 41%
1–2 days
14 17%
3–7 days
12 14%
1–4 weeks
13 16%
Over a month
10 12%

How the animals did

Recovered
9 6.1%
Still unwell when reported
62 42%
Died
21 14%
Euthanised
12 8.2%
Not known
43 29%

Problems reported at the same time

Liver problems
130 88%
Vomiting
74 50%
Lethargy
63 43%
Loss of appetite
56 38%
Diarrhea
45 31%
Kidney problems
42 29%
Leucocytosis
42 29%
Blood problems
35 24%

Age of the animals

Under 1 year
8
1–3 years
35
4–7 years
43
8–11 years
38
12+ years
23

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 elevated gamma-glutamyl transferase (ggt) in dogs?
147 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 2 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).

Elevated gamma-glutamyl transferase (ggt) with similar medicines

All reported side effects of Moxidectin in dogs · Medicines most reported with elevated gamma-glutamyl transferase (ggt)