\Milk sickness\ (Veter.) A peculiar malignant disease, occurring in parts of the western United States, and affecting certain kinds of farm stock (esp. cows), and persons using the meat or dairy products of infected cattle. Its chief symptoms in man are uncontrollable vomiting, obstinate constipation, pain, and muscular tremors. Its origin in cattle has been variously ascribed to the presence of certain plants in their food, and to polluted water.