Transient paralysis is a form of Marek’s disease. It is rarely observed and usually not fatal. Clinical signs appear 6–12 days after infection and persist for only a few days. The condition is often misdiagnosed as Newcastle disease. Ataxia and paralysis of the wings and, particularly, of the neck and legs may be observed. Predominantly 6–18‑week‑old replacement breeders are affected, and they usually recover. Further information on this rare condition is provided in the chapter on Marek’s disease.