2% Moxidectin + 12.5% Praziquantel. Effective in the treatment and control of large and small strongyles, encysted cyathostomes, ascarids, pinworms, horse stomach bots, and tapeworms. One administration of the recommended dose rate also suppressed strongyle egg production through 84 days.
I have used quest since it was first introduced with never a problem. I usually am vaccinating 10 horses a year from foals to aged. I do use ivermectin on a new horse first, now, as I have read of some problems
It's important to give this wormer in late summer before the strongyles encyst, and in early spring before the encysted worms emerge. Otherwise you could have a mass die off and a sick horse. Do your research