A Significant Health Problem

Calf scours or calf diarrhea can cause more financial loss to cow-calf producers than any other disease-related problem they encounter. Scouring is not in and of itself a disease--it is a clinical sign of a disease which can have many causes. The best description of what actually takes place is that the intestine fails to absorb fluids and/or fluid secretion into the intestine is increased. There can be many causes for this.

Consider this: a calf is approximately 70 percent water at birth. Loss of body fluids through diarrhea can produce extremely rapid dehydration. Dehydration and the loss of certain body salts (electrolytes � these include potassium, sodium, chlorine, etc.) produce a change in body chemistry and can cause severe depression in the calf. Although infectious agents (bacteria, viruses) 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 the delicate pH balance that is normal in the body. Understanding the infectious agent that causes scours is important, however, so we can understand how to control it.

Additionally, we also need to understand that the age of the calf when scours begins is important 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 nurses soon after birth and consumes 1 to 2 quarts of colostrum in the first few hours absorbs a higher level of antibodies. This calf is far less susceptible to scours and other calfhood diseases.

Infectious Agents Play a Major Role

Many �bugs� can create circumstances just right to cause scours in young cattle. These are of many different types and sources. Let's take a look at the more important of these:

1. Viral Scours � caused by a viral infection

A. Rotavirus Scours. Viruses of this type 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. This viral 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.

B. Coronavirus Scours. Scours caused by coronavirus occurs in calves that are over five days of age. When the infection first starts in a herd, calves up to 6 weeks of age may scour. These calves are not as depressed as those infected with rotavirus. 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 coronaviruses.

A vaccine that is specific for the rota- and coronaviruses is available. It is important that you consult your local veterinarian to determine the type of preventative and treatment program that will be most effective. Vaccines 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 build-up in the herd.

C. Bovine Virus Diarrhea. The virus of bovine virus diarrhea can cause diarrhea and death in young calves. Diarrhea begins two to three 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.

2. Bacterial Scours � Caused by Bacterial Infection

A. Escherichia coli (Colibacillosis). Escherichia coli (E. coli) has received a huge amount of coverage in the press as a health concern for humans and it has also been incriminated as a major cause of scours. Many different 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 type of E. coli. Diagnosis depends on an accurate history, clinical signs, and culture of internal organs for bacteria and typing of the organism. 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. There are new E. coli cow vaccines now on the market which is administered to the cow 6 weeks and 3 weeks prior to calving. The new E. coli vaccine is also available in combination with the rota- and coronavirus vaccine. This vaccination builds high antibody levels in the colostrum, but the calf must get colostrum in the first few hours of life for the vaccine to be effective.

B. Salmonella. There are more than 1000 types of salmonella, all of which are potential disease producers. Salmonella produces a potent endotoxin or 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 even a human carrier. Clinical signs associated with salmonella infection include diarrhea, blood in the feces, depression, and elevated temperature. The disease is more severe in young or debilitated calves.

C. 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. This disease is best controlled by vaccinating the cows with Clostridium perfringens toxoid 60 and 30 days before calving. A single booster dose of toxoid should be given annually thereafter before calving. If this problem is diagnosed in calves from nonimmunized cows, antitoxin can be given to the calf. Administration of antitoxin and oral antibiotics is the only treatment that is effective.

3. Other Causes of Scours

A. Coccidiosis. Coccidiosis is caused by one-celled parasites that invade the intestinal tract of animals. There are many species of coccidia. Two, Eimeria zurnii and Eimeria bovis, are usually associated with clinical infections in cattle. Coccidiosis has been observed in calves 3 weeks of age and older, usually following stress, poor sanitation, overcrowding or sudden changes of feed. It often occurs in calves 7 to 14 days after they are moved from the calving lots onto pasture. Clinical coccidiosis is generally diagnosed by finding significant numbers of parasites in the feces. A typical sign of coccidiosis in young calves is diarrhea with fecal material smeared over the rump as far around as the tail will reach. This may or may not contain blood. Death may occur during the acute period or later from secondary complications. Sulfonamides have been the treatment of choice for coccidiosis for many years. If treatment is given before signs appear, the disease can largely be prevented. Amprolium has been cleared for use in calves as a preventative. This should be supplied at the rate of 5 mg/kg of body weight for a period of 21 days to cover the time period during which this disease is anticipated. Good feeding practices, management, and sanitation are the control methods of choice.

Nutritional Scours

Under range conditions, a calf adapts a pattern of nursing that fills his needs. Nutritional scours can be caused by anything that disrupts this normal habit. A storm, strong wind, or the cow going onto new grass disrupts the normal nursing pattern. When the hungry calf does get an opportunity to nurse, the cow's udder may contain more milk than normal and the calf may overeat resulting in a nutritional scours. Erratic nursing patterns may also be conducive to enterotoxemia. Nutritional scours is usually white scours caused by undigested milk passing through the intestinal tract. This type of scours usually presents little problem in treatment. If the affected calves are still active and alert, no treatment is required. If the calf becomes depressed or fails to nurse, it should be treated. Oral antibiotics can be used as a treatment.

Treatment of Calf Scours

Treatment for scours is very similar regardless of the cause. It should be directed toward correcting the dehydration, and electrolyte loss. Antibiotic treatment can be given simultaneously with the treatment for dehydration. Dehydration can be overcome with simple fluids given by mouth early in the course of the disease. If dehydration is allowed to continue, intravenous fluid treatment becomes necessary. The clinical signs of dehydration first occur when the fluid loss reaches 5 to 6 percent of the body weight. Ten percent loss of fluid results in depression, sunken eyes, dry skin, and the calf will probably be unable to stand. A 15 percent loss of fluids usually results in death. Oral fluids used early in the scouring process have been quite successful. Consult your veterinarian for electrolytes to be given orally. There are dry electrolyte powders available that can be mixed with water for oral administration.

Conclusions

It is apparent that many factors can create a scouring situation in young cattle. The one factor that we observe, however, is that in almost every situation, prevention is linked to the appropriate intake of colostrums by the calf within a few hours of birth. It is important that calving conditions are good and that the producer observes newly born calves to insure that they are up and suckling as soon as possible. Additionally, a good herd health program is extremely important to prevent a potential onset.