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Mouse River Journal of Towner, North Dakota

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Raquel Dugan Dibble NDSU/McHenry County Extension Livestock Systems Specialist

Calf Scours: Causes and Prevention

Calf scours or calf diarrhea causes more financial loss to cow-calf producers than any other disease - related problem they encounter. Calf scours is not a disease—it is a clinical sign of a disease which can have many causes. In diarrheas, the intestine fails to absorb fluids and/or secretion into the intestine is increased.

A calf is approximately 70 percent water at birth. Loss of body fluids through diarrhea can produce rapid dehydration. Dehydration and the loss of certain body salts (electrolytes) produce a change in body chemistry and severe depression in the calf. Although infectious agents may be the cause of primary damage to the intestine, death from scours is usually due to loss of electrolytes, changes in body chemistry, dehydration, and change in acid-base balance rather than by invasion of an infectious agent. The infectious agent that causes scours is important, however, from the standpoint of prevention.

The age of the calf when scours begins is an important consideration in its survival. The younger the calf, the greater the chance of death. Recent research has indicated that many scour cases can be directly related to colostrum intake by the newborn calf. A calf that is well mothered and consumes 1 to 2 quarts of colostrum in the first few hours after birth absorbs a higher level of antibodies. This calf is far less susceptible to scours and other calf hood diseases.

Viral Scours Rotavirus Scours.

This virus can cause scours in calves within 24 hours of birth. However, when the infection - is first introduced into the herd, it can affect calves up to 30 days of age or older. Infected calves are severely depressed. There may be a drooling of saliva and profuse watery diarrhea. The feces will vary in color from yellow to green. Calves lose their appetite and the death rate may be as high as 50 percent, depending on the secondary bacteria present. Diagnosis depends on an accurate history, clinical signs, and proper specimen collection and submission to a laboratory. The virus infection alone causes no diagnostic gross lesions in the intestine, but there is an increased volume of fluid in both the small and large intestine.

Coronavirus Scours.

Scours caused by coronavirus occurs in calves that are over 5 days of age. When the infection first starts in a herd, calves up to 6 weeks of age may scour.

Initially, the fecal material may have the same appearance as that caused by rotavirus. As the calf continues to scour for several hours, however, the fecal material may contain clear mucus that resembles the white of an egg. Diarrhea may continue for several days. Mortality from coronavirus scours ranges from 1 to 25 percent.

Gross lesions are not significant. The intestine is often full of liquid feces. If lesions are observed in the intestine, they are the result of secondary bacterial infection.

Treatment for coronavirus scours is the same as that for rotavirus scours. Many herds have been found to be infected with both the rota - and corona viruses.

A vaccine that is specific for the rota - and coronaviruses is available. It can be administered in one of two ways: orally to the calf soon after birth; or as a vaccination to the pregnant cow. . The first year that a vaccination program is started in the beef cow herd, the cow receives two vaccinations—the first at 6 to 12 weeks before calving, and the second as close to calving as possible. The next year, the cows are given a booster vaccination just before calving. In herds where the calving period extends over more than 6 to 8 weeks, cows that have not calved at the end of a 6-week period should receive a second booster vaccination. Following this procedure insures that the calf receives a high level of rota-and coronavirus antibodies in the colostrum. However, the calf must receive adequate

colostrum, preferably within the first 4 hours after birth as the antibodies cannot be absorbed later than 24 hours after birth. This cow vaccination program fits well into a beef cow herd health program and helps prevent virus b

uild-up in the herd.

Diagnosis of Rota - and Coronavirus Scours.

Accurate diagnosis of viral scours can be made only by laboratory tests. Your veterinarian knows what material to submit for examination.

Bovine Virus Diarrhea.

The virus of bovine virus diarrhea can cause diarrhea and death in young calves. Diarrhea begins 2 to 3 days after exposure and may persist for quite a long time. Ulcers on the tongue, lips, and in the mouth are the usual lesions that can be found in the live calf. These lesions are similar to those found in yearlings and adult animals affected with bovine virus diarrhea.

Diagnosis is by history, lesions, and diagnostic laboratory assistance. Treatment is similar to that used for other viral scours. Bovine virus diarrhea is controlled by vaccinating all replacement heifers 1 to 2 months before breeding. Caution: do not vaccinate pregnant heifers or cows with modified live virus. Consult your veterinarian before starting a bovine virus diarrhea vaccination program.

Bacterial Scours

Escherichia coli (Colibacillo-sis). Escherichia coli (E. coli) has been incriminated as a major cause of scours. Many times this is the only organism identified following routine bacteriologic culturing. Certain E. coli can cause diarrhea. Many different serotypes (kinds) of E. coli have been identified; some cause scours while others do not. E. coli is always present in the intestinal tract and is usually the agent that causes a secondary infection following viral agents or other intestinal irritants.

E. coli scours is characterized by diarrhea and progressive dehydration. Death may occur in a few hours before diarrhea develops. The color and consistency of the feces are of little value in making a diagnosis of any type

of diarrhea. The course varies from 2 to 4 days, and severity depends on age of the calf when scours starts and on the particular serotype of E. coli.

Upon postmortem examination, lesions, are nonspecific. However, the small intestine may be filled with fluid and the large intestine may contain yellowish feces.

Diagnosis depends on an accurate history, clinical signs, and culture of internal organs for bacteria and serotyping of the organism. The location at which the culture from the intestine was taken is also important. Control of E. coli scours can be difficult in a severe herd outbreak. All calves should receive colostrum as soon after birth as possible. This helps the calf resist E. coli infection. Early isolation and treatment of scours helps to prevent new cases.

Salmonella.

There are more than 1000 types of salmonella, all of which are potential disease producers. Salmonella produces a potent endotoxin (poison) within its own cells. Animals may be more severely depressed following treatment with antibiotics as treatment causes the salmonella organisms to release the endotoxin, producing shock. Therefore, treatment should be designed to combat endotoxic shock.

Calves are usually affected at 6 days of age or older. This age corresponds very closely to the age of the coronavirus infection. The source of salmonella infection in a herd can be from other cattle, birds, cats, rodents, the water supply, or a human carrier.

Clinical signs associated with salmonella infection include diarrhea, blood and fibrin in the feces, depression, and elevated temperature. The disease is more severe in young or debilitated calves. Finding a membrane-like coating in the intestine on necropsy is strong presumptive evidence that salmonella might be involved. Salmonella isolations should be checked by a bacteriologic sensitivity test to determine the antibiotics of choice.

Enterotoxemia.

Enterotoxemia can be highly fatal to young calves. It is caused by toxins produced by Clostridium perfringens organisms. There are 6 types of Clostridium perfringens that can produce toxins, of which types B, C, and D appear to be the most important in calves.

The disease has a sudden onset. Affected calves become listless, display uneasiness, and strain or kick at their abdomen. Bloody diarrhea may or may not occur. It is usually associated with a change in weather, a change in feed of the cows, or management practices that cause the calf to not nurse for a longer period of time than usual. The hungry calf may over-consume milk which establishes a media in the gut that is conducive to the growth and production of toxins by the clostridial organisms. In many cases, calves may die without clinical signs being observed.



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Original Publication Date: March 31, 2010



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