Veterinary Clinical Medicine-I (General and Systemic)

NEONATAL DIARRHEA

• Diarrhea is the most important disease of neonatal calves and results in the greatest economic loss due to disease in this age group in both dairy and beef calves.

• Neonatal diarrhea in calves is a complex, multifactorial condition with factors such as pathogen exposure, strain variation, environmental and management conditions, nutritional state and immune status playing a major role in production of disease.
• Most of these factors are related to biosecurity in the calf rearing area and must be considered before developing a treatment plan for individual cases of the disease.

• Diarrhea is an increase in frequency, volume or fluidity of bowel movements.
• Fluidity is much less important in cattle than in other species.
• Cattle normally produce 15-28 Kg of feces per day that is 75-85% water.
• Mechanisms of diarrhea are one of more of the following: Malabsorption- decreased or damaged cellular absorptive area; Osmotic- increased number of particles within the lumen of the bowel holds water; Secretory- cyclic AMP and prostaglandin mediate active secretion into the bowel; Abnormal motility- increased or decreased transit time; Hydrostatic- increased blood to lumen pressure gradient such as with cardiac problems or inflammatory bowel disease.
• Pathogenesis of diarrhea is related to either increased secretion or decreased absorption.
• The normal bovine GI system absorbs only slightly more than what is secreted per day.
• Normal secretory amounts are equal to, or exceed the extracellular fluid amounts.
• Clinical signs of diarrhea are associated with dehydration, acidosis, depression, failure to nurse, weight loss, cardiac arrhythmias, sepsis and endotoxemia.
• Dehydration should be scored as a percentage of body weight and results in profound loss of circulatory volume.
• Acidosis increases vascular resistance, impairs cardiac function, and blocks catecholamine action.
• Hyperkalemia causes cardiac arrhythmias due to myocardial potassium imbalances.
• Shock and sepsis occur frequently in severe diarrheic cases. Signs of sepsis in calves include hypopion, arthritis, hyperesthesia, rigid neck, fever, and scleral injection.
• Remember that calves are born and raised in a wide diversity of environments and housing condition, which will affect the risk of enteric infectious disease.
• Ventilation is inadequate in many cases resulting in high humidity. Vermin such as flies and rodents are often present in high numbers and these vectors can become a significant factor in disease transmission.
• The most frequently recognized agents causing calf diarrhea include E. coli, rotavirus, coronavirus, cryptosporidia, coccidia and Salmonella.
• With the exceptions of Salmonella and specific strains of E. coli these organisms are ubiquitous in the environment and present within the GI tract of most healthy, mature cattle without clinical signs of infection.