Scours – What are they?

Newborn calves up to a month of age are the most susceptible to scours. Photo courtesy of David R. Smith, DVM, PhD, DACVPM (Epidemiology); Mississippi State University College of Veterinary Medicine.
Newborn calves up to a month of age are the most susceptible to scours. Photo courtesy of David R. Smith, DVM, PhD, DACVPM (Epidemiology); Mississippi State University College of Veterinary Medicine.

By Lindsay Chichester, UNL Extension Educator; Dr. Dee Griffin, Feedlot Production Management Veterinarian and Professor; and Dr. Richard Randle, UNL Professor of Veterinary Medicine

The temperatures are warming up, we have gotten a little bit of rain, the grass is starting to grow, and your calves may be susceptible to scours, or diarrhea. Diarrhea disrupts the normal absorption of fluids, nutrients, and chemical electrolytes such as sodium and potassium from the intestines, resulting in the calf becoming very dehydrated and metabolically imbalanced. Loss of essential body fluids and electrolytes leads to acid build up (acidosis) which may contribute to diarrhea and possibly death. Scours can be caused by viruses, bacteria, protozoa, nutritional imbalances, or a combination of any of those. If faced with scours it is important to immediately identify which type of disease you are dealing with so that a treatment plan can be made with your veterinarian. Scours can occur at any time of the year, not just during the birthing season, but newborn calves up to a month of age are the most susceptible. Diligent observation, appropriate nutrition, environmental awareness, proper sanitation, and care of the calf are things that should be taken into consideration to decrease the incidence of scours with your animals.

Virus: Depending on the environment and the virus, a virus can survive in an environment for varying periods of time. Viruses cause diarrhea by entering the body via the mouth. Once inside the calf, the virus will attach itself to healthy cells and will reprogram a healthy cell to either die or alter the function. A young calf can start to show symptoms within three days. Common types of viral scours are rotavirus and coronavirus both of which destroy the cells lining the small intestine resulting in diarrhea and dehydration. BVD (Bovine Virus Diarrhea) is another cattle virus that can cause diarrhea, but it is not typically associated with calf diarrhea.

Young calves are particularly susceptible to viral diseases; and adult and/or older juvenile beef animals can be asymptomatic carriers of a virus. This means they can pass viral agents to other animals without showing any signs of illness themselves.
Antibiotics do not work against viruses. There are vaccines, that when given to the cow, can provide antibodies through the colostrum (first milk) to the calf.

Bacteria: Bacteria are single-celled, microscopic organisms that can reproduce on their own. Like a virus, they can survive in the environment, as well as enter and infect a host. Bacterial infections can be treated with antibiotics. It is important to keep in mind that since bacteria are living organisms, they are adaptable and can produce strains that become and are resistant to antibiotics. Common causes of bacterial scours in young animals include: Salmonella, Escherichia coli (E. coli), and Clostridium perfringes (enterotoxemia).

Salmonella infection in a herd can come from contact with other livestock, birds, cats, rodents, the water supply, or human carriers. Salmonella produces a potent toxin which can be very devastating and cause a high morbidity and mortality rate, requiring environmental management and intense therapy for the animal. Salmonella rapidly develops resistance to antibiotics; it should be treated carefully and with a veterinarian’s guidance. Some of the symptoms include diarrhea, blood and fibrin in the feces, extreme depression, and elevated temperature. Salmonella infection in baby calves is typically fatal. Most importantly, Salmonella can cause life threating disease in humans. Therefore, isolate the clinically affected calf away from other animals, be extremely clean in your personal hygiene when working with affected animals, and keep others, especially children away from calves affected with Salmonella.

E. coli is the most common cause of bacterial scours. E. coli K99 bacteria attaches itself to the epithelial lining of intestines, ultimately resulting in voluminous diarrhea. Another type of E. coli is attaching and effacing E. coli, which attaches to the cell, resulting in cell death and changes the function of the intestine so that it cannot properly absorb fluid or properly digest nutrients. Intestinal linings generally have tremendous healing capacity, but if the damage is severe there could be lifetime problems for the animal.

Clostridium perfringes infections are also known as enterotoxemia. Enterotoxemia is fatal and is caused by toxins released by various types of Clostridium perfringes. This disease has a sudden onset; animals will become listless, strain or kick at their abdomen, and display uneasiness. This usually follows a change in weather, a change in the cow’s feed, or a change in management practices that will disrupt the nursing cycle for a longer than normal period of time. The hungry calf may then consume a large amount of milk, creating an environment in the gut conducive to growth and production of toxins by Clostridial organisms.

Protozoa: Protozoa are a type of living parasite that adhere to or invade the lining of the intestine, eventually rupturing the epithelial cells. Protozoa can be the cause of diarrhea in young animals, including cryptosporidia and coccida. The oocysts (eggs) of these protozoa can survive for months in the environment, even in pastures/pens that have been vacant. Animals are infected when they consume contaminated feed or water, graze contaminated pasture, or lick a dirty hair coat. Again, older animals may be carriers without showing signs. Cryptosporidiosis is of particular concern because there is no effective treatment available and it is zoonotic, meaning it can be transmitted to humans causing severe diarrhea.

Stress and nutrition: Stress and nutritional excess can also cause scours. Anything that may disrupt the normal nursing pattern - moving to a different pen/pasture, vaccinating, castration, even storms and extreme weather changes/conditions may cause enough stress to disrupt the nursing pattern. These scours will generally clear up in a few days, or once the stressor is removed. Nutritional scours can often be identified by white fecal matter which is undigested milk that has passed through the system.

Prevention: Two important things you need to know about scours; 1) it is critical to get high quality colostrum into the animal as soon as possible after birth. Cows that have had their immune systems properly prepared prior to giving birth will have high quality colostrum. The birthing environment should provide a quiet environment and attention must be paid to letting or assisting bonding between the cow and calf. 2) An equally important preventative measure is to protect the calf from fecal-oral contamination during the first few weeks of life. The best reference you can study in this regard is the UNL-Sandhills Calving System (

Treatment options: Oral fluids are the most important life-saving treatment you can provide. Any number of oral electrolyte preparations can be found from your veterinarian and animal health stores. Visit with your veterinarian about treatment options and methods for delivering oral electrolytes. While antibiotics are the first thing on everyone’s mind, generally, antibiotics have little if any effect on the outcome. Keeping the scouring calf hydrated and its electrolytes balanced is far more likely to save the animal’s life than an antibiotic. Because managing disease in very young animals requires intense attention to details it is important for you to visit with your veterinarian.

As a reminder: Scours are considered to be a zoonotic disease, which means it is transferable from animal to human. If working with or treating calves with scours, you should wear disposable gloves and/or wash your hands and clothing thoroughly. Do not wear dirty or contaminated shoes into the house. Wash and sanitize equipment that has come in contact with the sick animals, their bedding, or pen/pastures. Do not put dirty hands in your mouth or near your face, do not touch or hold small children, or pets. If you or a family member gets sick with diarrhea or abdominal cramping, let your doctor know you may have been exposed to livestock with scours so a quick and accurate diagnosis can be made.

Adams, T. (2014). Scours can be caused by virus, bacteria or more. Farm & Ranch Guide. Found online

Adams. T. (2014). When scours leaves the barn and enters the home. Farm and Ranch Guide. Found
online at:

Stoltenow, C. L. and Vincent, L. L. (2003). Calf scours: Causes, prevention, and treatment. Found online at