Moxidectin Wormer is the most widely used for Encysted Small Strongyle Larvae.
Now if you are not treating worms and are treating the "disease strangles" that is a different story! No wormer will help there as that is not caused by worms, it is a bacterial contagious upper respiratory tract infection.
Here is a good cheat sheet for wormers to use for certain types of worms!
They are small but very harmful, they infest the intestine, the liver, the pancreas and the vascular walls, cause anemia and lesions in the intestinal mucous membranes ... The larvae of certain varieties of strangles clog the arteries and intestine causing fatal colic.
There is no one treatment plan that is suitable for every case of strangles. Treatment often revolves around supportive care, good stable management and hygiene. Antibiotics may rarely be used and your veterinary surgeon will give you guidance based on your horse's individual circumstances.
The dewormer should be given before all this happens, once it is infected the deworming no longer serves much, only medical treatment can help.