This usually occurs in mid to late summer. Affected individuals are anemic, weak, off feed, and lose weight rapidly. Jaundice, or yellowing of the skin, is common but is only observed when the eyes, mouth, and other membranes are examined closely. Difficult respiration, fever of 105 degrees F or higher, dehydration, and constipation are common. Milk production of lactating cows declines dramatically.
Affected animals are often excitable or belligerent.
Death often occurs within 24 to 48 hours of the onset of symptoms and may be the first indication that anything is wrong in a herd. Abortion after recovery from clinical disease is common. In an infected herd, recovery from undiagnosed infection and development of a carrier state is actually more common than death. Many carriers were never known to have been sick. Infected carriers may be more susceptible to other conditions such as parasitism, severe winter weather stress, or malnutrition.