For my pony, yes. For others, probably not needed. Our temps are going from high 70’s down to low 40’s at night. Once temps stabilize a bit more he goes back to no issues.
I test 2-3 times a year to stay on top of his numbers and keep the right dosage as meds are $$. He’s at home so I micromanage everything about his care, probably too much.
He actually sheds and grows a fairly normal coat on the Heiro supplement and his prescription. Only thing odd is even with his thick coat he gets cold easily, so I have to blanket him heavier than the others.
ECIR site is the best for info and managing symptoms, all my info comes from them and my vet.