8 week old Columbian Wyandotte with Mereks
What hatchery did the chicks come from? Have you double checked with them to make sure they were vaccinated? I would try chick vitamins that contain riboflavin, on the chance that it might be curled toe paralysis from riboflavin deficiency. I'm not sure why the foot would be paralyzed while the leg was moving with Mareks disease. Tube feeding twice a day would be possibility. You might first try just putting the wet feed with raw egg for her to take on her own, and wait her out for a day.Here is a link about tube feeding:
Most people that use PolyVisol use 2-3 drops daily per chick, but with the powder vitamins in the water, they should get the correct dosage of all vitamins. The riboflavin dosage is here from The Merck Manual:
Chicks receiving diets only partially deficient in riboflavin may recover spontaneously, indicating that the requirement rapidly decreases with age. A 100-mcg dose should be sufficient for treatment of riboflavin-deficient chicks, followed by incorporation of an adequate level in the diet. However, when the curled-toe deformity is longstanding, irreparable damage occurs in the sciatic nerve, and the administration of riboflavin is no longer curative.
Most diets contain up to 10 mg of riboflavin/kg. Treatment can be given as two sequential daily 100-mcg doses for chicks or poults, followed by an adequate amount of riboflavin in feed.
Here are a couple of good articles about Mareks disease:
Most any poultry vitamin except Poultry Nutri-drench will work, but just read the label to make sure it contains riboflavin. Nutritional yeast or B Complex tablets can also be used. I would just use what you have until you need more. It's always good to keep some vitamins with electrolytes around when you have a sick chick or it is very hot in summer.