News

Rotavirus is one of the most common viruses associated with calf diarrhea. Diarrhea usually develops between 3 and 7 days of age. There may be a drooling of saliva and profuse watery diarrhea. The feces will vary in color from yellow to green. Rotavirus infects cells essential to the absorption of nutrients in the small intestine. The lack of small intestine nutrient absorption causes nutritional deficiencies for the calf, and interferes with the rest of the digestive tract’s ability to absorb water. Not all calves with rotavirus have diarrhea. Calves lose their appetite and the death rate may be high. Death losses are consistently associated with pronounced dehydration. The infection may be short lived but the intestinal lining has to recover from damage.

Coronavirus is a cause of diarrhea in young calves. The virus is able to infect epithelial cells of the small intestine (gut), causing them to die. Moderate to severe diarrhea will follow, lasting for 4 to 7 days. Affected calves are usually between 1 and 3 weeks of age. The calf may have a high temperature or in some cases abnormally low temperature. The calf loses the ability to digest and absorb milk. Coronavirus also damages the cells in the intestinal crypts and slows down the healing process in the intestinal lining. Furthermore, the damage caused by Coronavirus is often compounded by bacterial infections and the risk for fatal diarrhea is increased when mixed infections occur. Infected calves are severely depressed with excessive drooling and watery diarrhea; fecal color varies from yellow to green. The abdomen may be drawn in and drugs have practically no effect on the diarrhea. The calf may strain to defecate or feces are forcefully ejected.

The Salmonella species of bacteria have been associated with calf enteritis but like E. coli, Salmonella has a strong tendency to spread beyond the gut and cause widespread disease. The result of this invasion is damage to the tissue, so that water and food cannot be absorbed. Salmonella can readily invade the rest of the body, causing blood poisoning and rapid death. Salmonella produces a potent toxin or an endotoxin (poison) within its own cells. Clinical signs associated with Salmonellosis include bloody diarrhea, fibrin in the feces, depression and elevated temperature. The disease is more severe in young or debilitated calves. Infected calves can shed the organism in feces, urine, saliva and nasal secretions, contaminating everything they touch and everything that touches them.

Escherichia coli is almost the only diarrhea that occurs within the first three days of life, often on the first day. The E. coli bacteria releases a toxin that damages the cell lining of the gut, causing the normal absorptive capacity of the intestine to change and results in fluids and electrolytes being secreted and lost. This process can pump so much fluid into the gut that the calf dies before the external signs of diarrhea appear. Prevention involves cleanliness and vaccination of cows followed by proper colostrum management.