Ok sorry Ryle, my vet is wrong again. Gee, whereever did she get her education? Walmart? I will let her know she told me wrong.
I dare say that east Texas certainly has MUCH different weather than northern MN. Up here, its frigging cold. Cold enough that most people from TX that come visit in winter never come back.
And here is a PDF from the Horse.com that says Freezing KILLS Small Strongyle eggs.
Please see the paragraph right where it says "The Climate Controlled Worm".
So while YOUR strongyle eggs might gleefully overwinter, ours do not. We deworm after the first killing frost, and our horses enjoy a 7-8 month break from parasite infestation.