Behaviour change after Moxidectin (ProHeart 6) in dogs

The FDA has received 688 reports of behaviour change in dogs after Moxidectin. That is 1.4% of all reports for this medicine, compared with 2.5% across reports for all dog medicines, so it is reported less often than average with this medicine.

688Reports
40%Marked serious
22%Recovered
13%Died or euthanised
Same dayTypical onset
SponsoredWorried about your pet? Ask a veterinarian online, 24/7

How soon it started

Same day
283 54%
1–2 days
85 16%
3–7 days
44 8.4%
1–4 weeks
41 7.8%
Over a month
71 14%

How the animals did

Recovered
148 22%
Recovered with lasting effects
3 0.4%
Still unwell when reported
286 42%
Died
58 8.4%
Euthanised
32 4.7%
Not known
161 23%

Problems reported at the same time

Age of the animals

Under 1 year
36
1–3 years
270
4–7 years
204
8–11 years
118
12+ years
42

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 behaviour change in dogs?
688 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 the same day 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).

Behaviour change with similar medicines

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