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Calf scours

Calf Scours

Signs, prevention and treatment

Calf scours, or diarrhea, is a number one health issue for newborn calves. The majority of health problems in a cow’s early life relate to diarrhea. Scours is the most common cause of death in young unweaned calves, and is associated with poor growth, increased labor requirements and increased costs for producers.

While the causes of scours vary, scours in cattle is almost entirely avoidable by good management, proper feeding and prevention. Treatment options are available depending on the particular cause.


In the United States, calf scours occur in nearly 1 out of every 4 young animals (NAHMS Dairy 2007). A full 23.9% of dairy heifers are affected by and treated for scours and pre-weaning mortality is estimated at 7.8% according to Cornell University and the National Animal Health Monitoring System (NAHMS, 2007), respectively.

Signs and symptoms of calf scours

Clinical signs of diarrhea start with thin loose watery feces that progress with signs of dehydration, sunken eyes, dry mucus membranes, and changes in the coat (rough hair syndrome).

Calf diahrrea symptoms may include:  

  • a loss of appetite 
  • sunken eyes   
  • difficulty to stand up or stay standing 
  • Signs of colic 
  • Blood and fibrin in feces 

If not properly treated, calves may fall into a hypoglycemic coma or even die.  

Table 1: Assessing Dehydration

Clinical SignPercent Dehydrated
Few clinical signs<5%
Sunken eyes, skin tenting for 3-5 seconds6-7%
Depression, skin tenting for 8-10 seconds, dry mucous membranes8-10%
Recumbent, cool extremities, poor pulse11-12%

Source: Sheila M. McGuirk, DVM, PhD, and Pamela Ruegg, DVM, MPVM. University of Wisconsin-Madison

Causes of scours 

Cattle develop diarrhea in any age as a reaction to agents that cause disturbance or disruption in the gastrointestinal tract. There are variety of the agents that may cause disturbances in the gut, acting separately or in many cases also in a group. There is a variety of agents that may cause disturbances in the gut, acting separately or in many cases also in a group.

Bovine diarrhea is influenced by the combination of four factors: 

  1. Feeding
  2. Management
  3. Immune system
  4. Pathogens and toxins

Major enteric pathogens known to cause calf scours include:

  • Viruses including bovine rotavirus (BRV) and bovine coronavirus (BcoR), bovine viral diarrhea virus (BVDV)
  • Parasites such as Cryptosporidium (C.) parvum and coccidia
  • Bacteria including Escherichia coli, Salmonella species, and Clostridium perfringens 

Stressors such as dehorning, vaccination, tail docking, feed changes, environmental changes and other management and environment factors can also contribute to diarrhea. 

  • Change in feeding routine (time, temperature and consistency)
  • Malnutrition (early introduction of nutrients that needs adaptation) 
  • Compromised feed hygiene (bacterial load)
  • Insufficient pen management and sanitation
  • Overstocking of calves in pens
  • Dirt and high humidity 

Factors inducing scours in adult cattle:

  • Ingestion of toxins including plant toxins and mycotoxins, or nitrate coming from the forage.
  • Rapid change in the diet without short adaptation period (lush pasture or introducing too much grain in the diet causing acidosis) 
  • Digestion of large quantities of highly fermentable feed (especially fresh cows in early lactation)
  • Heat and heat stress 
  • Infectious disease

How to treat scours in calves

Often, a calf is infected with more than one pathogen and in most cases, despite the fact that pathogens differ from each other, the clinical picture is similar: intestinal enteritis with diarrhea causing death, due to rapid dehydration. It is worth noting that calves die because of fluid and electrolyte loss not because of pathogenic infection. 

Oral fluids therapy administered early on is the most effective way to counteract dehydration. Remember, it is never too early to start offering electrolytes to scouring calves. Similarly, it is often better to keep on feeding the scouring calf—just increase number of meals, reduce feeding portion, and hydrate with oral fluids containing electrolytes.

Table 2. Fluid Requirements for Treatment of Diarrheaa

Calf Health% DehydratedDaily MilkOral Fluids
Healthy calf0%4.4 kg0 kg per day
Mild diarrhea2%4.4 kg1.1 kg per day
Mild diarrhea4%4.4 kg2.2 kg per day
Depressed6%4.4 kg3.3 kg per day
Very ill8%4.4 kg4.4 kg per day
Recumbent>10%4.4 kgNeed intravenous fluids

should be fed separately from electrolytes

Prevention and control of calf diarrhea should start from colostrum management.

How to prevent calf scours 

Calves are born with no functioning immune system, sterile and naive. The first risk of infection is the calving pen and the mother. A clean calving pen and fast separation from the mother will reduce pathogen exposure. Ensure pre-weaned calf health by focusing on these 5 key areas.  

A calf scours prevention program should include:  

  1. Minimization of pathogen exposure 
  2. Vaccination program developed with veterinarian carried out using proper timing and technique 
  3. Proper colostrum and feeding management 
  4. Early identification of sick calves and intervention 

Source : Sheila M. McGuirk, DVM, PhD, and Pamela Ruegg, DVM, MPVM 
University of Wisconsin-Madison 

Scours prevention should include a strategy to reduce diarrhea in adult’s animals. Adult animals’ feces spread pathogens to the environment-causing diarrhea in young animals. 

Favor colostrum

The open gut phenomena that keeps on closing with after birth, is the best way to get immunity transfer with colostrum from dam to the newborn. Feeding good quality colostrum 3-4 liters by drench or bottle within 2 to 4 hours after birth is the best practice to create calves’ immunity and prevent scours.  

With good colostrum, young animals receive fast energy shot with immunoglobulins, immune related factors, lactoferrin, lysozyme, growth factors, hormones, minerals, vitamins to create its own immune system against pathogens. It is a good practice to continue feeding colostrum or transition milk 2 to 3 days after birth. Colostrum feeding for the first 3 days increased mucosal growth and absorption capacity (Steinhoff Wagner 2014).   

Milk versus milk replacer 

There is an ongoing discussion what is better feeding milk or calf milk replacer and both methods have their proponents. It is important to note that whatever method we use we need to keep the bacteria load down. 

Milk and milk replacer create a very good environment for pathogen multiplication, especially environmental E. coli or Salmonella. In many farms there is a tendency to adopt stronger pasteurization, use acidified milk or essential-oil based phytogenic products to strengthen cows’ immunity and reduce pathogens. Lastly, any changes in feed should follow short adaptation period to increase better digestion (from colostrum to milk, from milk to milk replacer).


National Animal Health Monitoring System, United States Department of Agriculture, 2002.

National Animal Health Monitoring System, United States Department of Agriculture, Dairy 2007.

National Animal Health Monitoring System, United States Department of Agriculture, 2007.

Sheila M. McGuirk, DVM, PhD, and Pamela Ruegg, DVM, MPVM. University of Wisconsin-Madison



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