Salmonella is another common bacterial cause of scours in calves. There are many different species of salmonella that can cause problems in calves, the most common species is Salmonella typhimurium. Salmonella is a common inhabitant of the GI tract of cattle and is present in manure. Calves usually become infected shortly after birth, when manure from infected or carrier animals is ingested. Salmonella is a common cause of scours in herds assembled from different sources. Infections can be caused by contaminated feeds or milk replacer, especially during the summer when high temperatures cause feed spoilage.

Salmonella usually affects calves that are greater than two weeks of age; however, it can be seen in calves as young as two days old. The clinical signs of a Salmonella infection are watery feces with a gray, dark brown, black or bloody appearance, dehydration, weakness, and a high fever. Calves usually die within 12 to 48 hours after the first signs appear. There is a very high mortality rate among infected calves. Because of the high mortality rate, successful treatment requires intensive antibiotic therapy. Antibiotic resistant strains of Salmonella have been identified.


Calfhood Scours
By: David Marcinkowski
Dairy Specialist
University of Maine Cooperative Extension

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Calfhood scours, or diarrhea, can be a problem in many beef and dairy herds. Scours is one of the most common diseases affecting calves before one month of age. It also results in most of the economic and death losses of calves in that age group.

Scours is not a specific disease caused by a single infectious organism, but a symptom produced by many different pathogens. Scours can be caused by bacteria, viruses, protozoa, stress, improper nutrition or any combination of these problems. This complicates the identification of the cause or causes of specific outbreaks.

Some common bacterial causes include Escherichia coli (E.coli), various species of Salmonella and Clostridium perfringens. Viral causes include rota, corona, and BVD viruses. Two common protozoal causes of scours are coccidia and cryptosporidia.

Prevention of Scours
The old adage, "an ounce of prevention is worth a pound of cure," is especially true when dealing with scours. Effective control of scours is accomplished by the application of the sound management practices listed below.

Reduce the exposure of calves to scours causing organisms. This is accomplished by keeping the maternity area clean, dry, and well bedded. Calving areas should be free of animals before the calving period.
Reduce animal densities in maternity and nursing areas. Wash and disinfect the udders of expectant cows before calving. Keep newborn calves, clean, dry, and warm. Clean and sanitize any feeding and treatment equipment. Observe calves for possible health problems several times a day. Isolate sick calves and treat them promptly and thoroughly.

Build up adequate immunity in newborn calves with colostrum. The newborn calf gains immunity to disease by absorbing the antibodies it needs from the gut directly into the blood stream from the mother's colostrum. Maximum immunity to disease is obtained when the calf receives an adequate quantity of a quality colostrum soon after birth. Studies in dairy herds have shown that 60 percent of Holstein calves will not receive adequate immune protection by simply allowing them to nurse. Make sure calves receive at least four to six percent of their body weight in first colostrum within one hour of birth, by bottle feeding. Force feed the colostrum with a stomach tube if the calf refuses to drink. There are several colostrum substitutes that are available commercially. These products are expensive to use and may not provide the calf with the same level of immunity as fresh colostrum from the dam. However they can be a useful alternative when fresh or frozen colostrum is unavailable.

Increase the colostral immunity to scours organisms by vaccination of the pregnant dam. Consult with your veterinarian to develop a comprehensive vaccination program for your herd and area. There are many vaccines available to provide pregnant animals with additional immunity to scours causing bacteria and viruses. These include E. coli, Salmonella, Clostridium perfringens, rota and corona viruses and BVD. Monoclonal antibody products specifically for the K99 strain of E. coli are available. These products come in a paste or tablet form that can be given to calves following birth. The antibodies in these products are absorbed into the blood just like colostral antibodies. However these products only increase the calf's immunity to the strain K99 of E. coli and none of the other scours organisms.

Provide adequate nutrition and sound management to reduce stress. Balance rations to meet animal requirements and maintain adequate body condition in pregnant cows. Feed recommended levels of good quality milk replacers. Feed calves at the same times each day. Provide animals with additional energy in cold weather. Keep sick calves isolated, warm and dry.

To understand the treatment of scours it is important to first understand, "What kills the scouring calf?" The diarrhea is caused by the organism producing toxins, inflammation and damage to the lining of the intestines. No matter what the cause of the diarrhea, the result is that the calf loses tremendous volumes of water and electrolytes in the feces. The dehydration caused by the loss of water and electrolytes is the primary reason most calves die from scours. The other major cause of death is starvation caused by the calf's lack of appetite and the decreased ability of the gut to absorb nutrients. In some cases starvation is caused by the prolonged withholding of milk by farmers in an attempt to treat the disease.

Effective scours treatment must first address the dehydration and starvation caused by the diarrhea. Dehydration is treated by using electrolytes solutions. The clinical signs of mild dehydration include, skin inelasticity, mild depression, a dry mouth, and the calf being unable to stand. Oral electrolytes should be used to treat mild cases of dehydration. Effective commercial electrolyte products that are mixed with water are available from veterinarians and farm supply stores. Also, homemade oral

electrolyte solutions can be mixed from common household products. It is important to follow directions precisely when mixing any oral electrolyte solution.

Oral electrolyte therapy is most successful when given early. Treat scouring calves now, don't wait until the next feeding. Waiting gives the scours organisms a better head start. Electrolytes are not very palatable. When the calf refuses to drink, then the oral solution should be given using a stomach tube. Oral electrolyte solutions should be warm to avoid temperature shock to the calf. Healthy calves should receive 10% of their birth weight in milk or milk replacer per day. Scouring calves lose large quantities of fluid, increase total fluid consumption per day (milk, replacer and electrolytes) up to 20% of birth weight. This can be done by feeding more than two times per day depending on the severity of the dehydration.

One controversial question about the use of oral electrolytes is whether to withhold milk and milk replacers during treatment. Recent research indicates that to avoid starvation, continue to feed milk or replacer at the same rate as usual. Between these normal feedings give the calves the oral electrolyte solutions. Allow 2 to 4 hours between a feeding and treatment with electrolytes. Never mix electrolyte solutions into milk or replacer.

The clinical signs of severe dehydration are severe depression, sunken eyes, cold legs, and failure to stand. Calves with severe dehydration should continue to receive oral electrolytes, but should also be treated with subcutaneous and intravenous fluids. Consult with your veterinarian on the proper techniques and products for these types of treatment.

Oral and injectable antibiotics are commonly used to treat scours. However, they are only effective against bacterial causes of the disease. It is difficult to determine the cause of a specific outbreak without diagnostic cultures and sensitivities. Initially there is little time to submit samples for laboratory analysis. At the onset, sick calves may be blanket treated with an antibiotic based on previous experience. If a response does not occur in 24 to 48 hours, it is unlikely that further treatments with that drug will be beneficial.

It is difficult to learn the cause of a particular case of scours based on the clinical signs alone. Many cases of scours are complicated with several different organisms and similar clinical signs. Also, some strains of bacteria are becoming resistant to commonly used antibiotics. For these reasons, it is important to use your veterinarian to perform examinations and collect the necessary samples for diagnostic analysis. Too often samples are submitted for laboratory analysis too late in the process to save some calves.

Bacterial products are sometimes feed to calves for the prevention and treatment of scours. These products are usually pastes or powders that contain live bacterial cultures. These bacteria are beneficial because they promote a better intestinal environment which makes the calf more resistant to infection. Studies suggest that these products can be beneficial in reducing the incidence and duration of scours.

Work with your veterinarian to develop specific treatment and prevention protocols based on the organisms common in your herd. Put these protocols in writing and make sure they are carried out. Everyone that works with the calves must know what treatments are to be used for the following situations:

  • Calf with mild diarrhea, no depression;
  • Calf with moderate diarrhea with depression;
  • Calf with severe dehydration and depression;
  • Calf with diarrhea and respiratory problems.

Finally, accurate health and treatment records should be kept on every animal in the herd. Good records will provide you with the information to make an accurate of diagnosis, determine the effectiveness of treatment and prevention measures and reduce the risk of drug residues.

Clostridium Perfringens
Clostridium perfringens is a species of bacteria commonly found in the soil that occasionally causes scours in young calves. Clostridium perfringens causes a disease known by a number of names including enterotoxemia, overeating disease and sudden death syndrome. It can affect animals of any age. This disease normally affects the healthiest and most aggressive eating calves in a group. When a calf overeats, conditions in the small intestines become optimum for the growth of this bacteria. As the bacteria grow, a powerful toxin is produced which enters the blood and causes death.

The clinical signs of clostridium perfringens enterotoxemia are discomfort, kicking of the abdomen, severe abdominal pain and a rapid violent death. Animals may die so quickly that scours is not seen. Prevention involves feeding a balanced ration, avoiding sudden changes in the diet and vaccination with Clostridium perfringens toxoid C & D.

Rota and Corona Virus
Two of the main viral causes of scours are the rota and corona viruses. These viruses attach to the small intestines and destroy the cells that line the intestinal villi. Damaged cells are normally replaced in 72 to 96 hours. The temporary loss of these cells, makes the calf is unable to digest lactose or milk sugar which causes the diarrhea. Viral infections of the small intestine also make the calf more susceptible to bacterial infections such as E. coli and Salmonella.

Clinical signs of rota and corona scours are a profuse watery scours, near normal body temperature, depression, and dehydration. Cases uncomplicated by bacterial infections are usually not severe and animals will recover in 18-24 hours. Clinical signs are normally seen in calves that are one to two weeks of age. Because these are viral diseases, antibiotics are ineffective except in the prevention of secondary bacterial infections.

Bovine Viral Diarrhea (BVD)
The BVD virus is commonly found in cattle populations throughout the world. The disease is very complex and can cause a variety of clinical signs depending on when the animal becomes infected. If infection with the virus occurs after birth, the calf may possess a high fever, respiratory problems and severe diarrhea. In milder cases, calves may show few if any clinical signs. The BVD virus can cross the placenta and infect the fetus anytime during pregnancy. If the fetus is infected during the first three months of gestation, antibodies against the virus cannot be produced and the animal will remain chronically infected for life. Infection of the fetus can cause abortion, birth defects, lower birth weights, unthriftiness and mucosal disease. The results of mucosal disease are a severe diarrhea, excess salivation and erosion in the mouth and other mucous membranes. Chronically infected calves can be weak and grow poorly but they can also appear normal. Studies indicate that about 2% of all calves are chronically infected with BVD. This makes it very easy to introduce BVD-infected animals into any herd. Chronically infected animals continue to shed virus throughout their life.

Prevention of BVD involves testing animals for chronic infection prior to entrance into the herd and vaccination of the entire herd against BVD. Antibiotics are of little help against a BVD infections, however they may be important in preventing secondary bacterial infections.

Coccidia and Cryptosporidia
Coccidia and cryptosporidia are similar parasitic protozoal diseases that cause scours in cattle of any age. These diseases are common throughout the United States and found in nearly all cattle populations. Both diseases are caused by organisms that lay dormant in manure and soil for up to one year. These dormant eggs or oocysts enter the body through contaminated feed and water. Once in the intestines of the animal, the oocysts release protozoa that multiply and enter the cells of the intestinal lining. These infections cause considerable damage to the intestinal lining causing malabsorption of nutrients and the clinical signs of the disease. Infected animals shed oocysts in their manure that contaminate the environment for other animals.

There are two different forms of the disease, a subclinical or chronic form in which animals show few outward signs of the disease, but suffer due to reduced feed consumption, feed conversion, and growth. Clinical signs of the acute form of these diseases include diarrhea (often containing blood), dehydration, depression, weight loss, and death. Protozoal forms of scours are often complicated with bacterial and viral scours organisms. Treatment with antibiotics is ineffective.

Cleanliness is the primary method of prevention for these diseases. Calves should be kept clean and well bedded to reduce exposure to infected manure. Avoid dirty pens and standing water. Keep feed and water off the ground. Outbreaks are usually more severe during wet weather. Storage of manure from infected animals may help reduce the number of oocysts. Growth promotants such as monensin, decoquinate, and lasalocid may help prevent outbreaks. Treatment of coccidiosis is difficult because the drugs used in treatment will not completely kill the organism and animals that remain in contaminated surroundings will continue to become reinfected.

E. coli
E. coli is a type of bacteria that causes a condition commonly known as "white scours." E coli is the most common cause of scours in calves. E. coli is a common inhabitant of the GI tract. There are many different strains of the bacteria found in cattle and other animals. Many strains of the bacteria are harmless to calves; however, there are several strains that can cause moderate to severe cases of scours and even death. The most common strain of scour causing. E. coli is called K99. E. coli also causes a form of mastitis in cattle; however, E. coli mastitis is caused by different strains than those that normally cause scours.

E. coli causes scours when a toxic strain of the bacteria is ingested and attaches to or invades the cells that line the surface of the small intestines. The bacteria produce toxins that attach to the intestinal cells and cause fluids to pass from the tissues and blood into the feces.

E. coli usually enters the calf shortly after birth and is commonly seen in calves less than 10-days old. The bacteria enter the body when calves ingest manure from infected animals. Unfortunately, the digestive tract of the newborn calf can absorb infectious organisms just as easily as colostrum antibodies. Calves that ingest E. coli before receiving adequate quantities of colostrum are most susceptible to E. coli scours. The clinical signs are yellow or white feces, with the calf appearing dull, weak, and depressed. The body temperature may increase during early stages of the disease, but usually returns to normal or subnormal temperatures due to the toxins produced. As the disease progresses, the calf will continue to lose weight and body fluids, stop eating, fail to stand, lie flat, and die. In severe cases, calves die within 12-24 hours after the first signs are noticed. It is common for other organisms such as rota and corona viruses to be present with E. coli. Combinations of infections can lead to more severe cases of diarrhea. Treatment usually involves the use of oral or injectable antibiotics. However, indiscriminate use of antibiotics can lead to resistant forms of the disease. With any bacterial form of scours the submission of samples for antibiotic sensitivity analysis will help identify the most effective drugs to use.