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Calf Health: Calf Scours Basics - Bacteria
Calf scours or diarrhea is a very costly problem for many producers. Calf scours is not the actual disease that plagues the calves, it is only the clinical sign that we see. Calves that suffer from scours can become critically ill in a short time. The pathogens that are the causative agents of this disease are not the actual causes of death in affected calves. Dehydration, electrolyte depletion and acid-base imbalances are the underlying causes of the animal’s demise.
Several types of etiologies can lead to diarrhea in calves. The type of agent that is responsible for the neonatal diarrhea is usually determined by the calf ’s age as well as the integrity of the calf ’s immune system. If the calf fails to receive the proper amount of colostrum, it will be more susceptible to the pathogens that cause neonatal diarrhea.
Bacteria
The most important bacterial cause of scours in calves is Escherichia coli (E. coli). It typically affects calves from one to five days of age. By releasing a toxin in the intestine, it precipitates what is termed a hypersecretory diarrhea. Signs include severe watery diarrhea that is generally yellow to white in color. Calves are normally nonfebrile and exhibit no blood, fibrin or mucus in their stool. This particular E. coli is called the K99 strain due to a specific protein found on its outer surface. Diagnosis can be made using a K99 test kit to demonstrate the presence of this bacteria. Failure to promptly treat this disease may lead to certain secondary problems such as meningitis or polyarthritis.
A pathogen that can be highly fatal in young calves is Clostridium perfringens. It is usually seen in calves less than seven days old.
The clinical signs produced by this bacteria are due to its release of an enterotoxin. There are six types of toxins released by C. perfringens, of which types B, C and D seem to be the most important in calves.
This disease has a sudden onset, and some calves will die without showing any symptoms of disease. It is usually associated with an increased intake in the calf ’s diet. Therefore, if management practices (penning the cows separate from the calves) or the weather cause an increase in the interval between meals, a calf may overconsume milk and thereby establish the proper environment for the bacteria to grow.
Clinical signs include lethargy, abdominal distention, bloody diarrhea and uneasiness (straining or kicking at abdomen). Postmortem lesions normally seen are bloody, fluid-filled small intestines which give rise to the common name “purple gut.”
Source: Jeremy Powell, DVM, Extension Veterinarian, University Of Arkansas Division Of Agriculture
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