Loss of appetite after Ivermectin + Praziquantel in horses

The FDA has received 292 reports of loss of appetite in horses after Ivermectin + Praziquantel. That is 11% of all reports for this medicine, compared with 9.2% across reports for all horse medicines.

292Reports
26%Marked serious
23%Recovered
5.5%Died or euthanised
Same dayTypical onset
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How soon it started

Same day
62 71%
1–2 days
12 14%
3–7 days
4 4.6%
1–4 weeks
0 0.0%
Over a month
9 10%

How the animals did

Recovered
65 22%
Recovered with lasting effects
1 0.3%
Still unwell when reported
10 3.4%
Died
15 5.1%
Euthanised
1 0.3%
Not known
200 68%

Problems reported at the same time

Age of the animals

Under 1 year
7
1–3 years
14
4–7 years
28
8–11 years
43
12+ years
135

About this medicine

Ivermectin prevents heartworm disease (monthly). Praziquantel treats tapeworms.

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 + Praziquantel cause loss of appetite in horses?
292 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).

Loss of appetite with similar medicines

All reported side effects of Ivermectin + Praziquantel in horses · Medicines most reported with loss of appetite