Ducklings fed on a diet of skimmed milk powder, casein, corn-starch, lard, cod liver oil, yeast, salts and paper pulp rapidly develop a disease characterized by extreme and progressive myasthenia, ending in death within a few days.
Pathological changes are found in the skeletal muscles. These show widespread hyaline necrosis of fibers, with edema and cellular reaction. The brain and other parts of the central nervous system are not affected, and no significant alterations are found in other viscera or tissues. The creatine content of the muscles is reduced in proportion to the muscle injury. Controls on a natural food diet remain free from the disease.