When the intestine is damaged by scours pathogens, the water and nutrients in the dam's milk can't be completely absorbed into the calf's bloodstream. As a result, a large fraction is lost from the calf's body in the diarrhea. This loss is the greatest threat to the survival of a scouring calf. Therefore, it must be a primary treatment focus.

The fluids lost in the diarrhea quickly deplete the calf of water and salts, producing symptoms of dehydration -- sunken eyes, weakness, and dryness to the mouth and nostrils. As the calf loses body fluid through diarrhea, its blood thickens, making it harder for its heart to deliver blood to its tissues.

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Meanwhile, the loss of salts from the calf's body creates an imbalance in the normal pH of the calf's system. As acidity takes over, acidosis sets in.

Calves with acidosis are weak and uncoordinated, often exhibiting a drunken, wobbly gait when made to walk. When encouraged to nurse, their suckle response is just a weak chewing motion. As acidosis worsens, the calf can't stand, becoming lethargic and sleepy.

Very advanced cases become comatose. The function of the heart and lungs is greatly impaired in cases of acidosis, and many advanced cases die of cardiac arrest.

Low Blood Sugar

For scouring calves, another common problem in cold weather is low blood sugar. The calf expends its own sugar reserves trying to keep warm. If it can't absorb milk nutrients from its damaged intestine, its sugar reserves aren't replenished.

Calves with low blood sugar usually develop subnormal temperatures (below 100 degrees F) as they lose the ability to maintain body heat. Low blood sugar contributes to the symptoms of weakness and lethargy induced by acidosis.

Thus, several problems are simultaneously at work: dehydration, acidosis and low blood sugar. If the calf didn't get adequate amounts of colostrum the first day of life, simultaneous infections in other organs can also be present.

Treatment involves correcting the fluid deficit and electrolyte imbalance. The use of antibiotics in cases of non-specific diarrhea is controversial within the veterinary profession. Barring a history of Salmonella or signs of systemic infection, such as a swollen navel or swollen joints, the use of antibiotics in non-specific diarrhea of calves is inappropriate. It will usually not affect the outcome, but it rarely makes things worse.

The key to proper therapy is to realize the magnitude of the fluid deficit. A 100-lb. calf that's 10% dehydrated needs 10 lbs. of fluids to just correct the immediate deficit. If 1 gal. of fluids weighs 8 lbs., the calf needs somewhere around 1.25 gals. Giving a calf 2 qts., two to four times a day, may be necessary to correct and maintain the fluids.

Severe dehydration must be corrected using intravenous treatment. In addition, most calves with diarrhea will be acidotic. Electrolyte solutions with an alkalinizing agent such as bicarbonate are then necessary. Carefully read the label to find products that contain bicarbonate. Usually, they're more expensive but are worth it.