Wooden tongue is fast acting. If they don't get treatment right away, or the second course of treatment when it severe, it can kill them. Think about what happens to the body. if the tongue swells and protrudes what happens to the back of the throat, the airways? They close up or swell up or become blocked. Lack of food, water, and the ability to breathe in enough oxygen to sustain the body and the brain.
We saved a cow from it, but we bypassed the LA200 and went straight to the vet for iodine by IV. We got lucky by probably catching it early. It was two vet calls, and touch and go for several days.
Wooden tongue is so hard on the cow that ours did not breed back that year. She lost a lot of condition in a really short time.