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What causes white scours in calves?

White scours in calves, also known as neonatal calf diarrhea, is a common condition affecting newborn calves. It is characterized by watery, white to gray diarrhea within the first few days of life. White scours can lead to dehydration, electrolyte abnormalities, and even death if not treated promptly. Understanding the causes and risk factors for neonatal calf diarrhea is key to preventing outbreaks on dairy and beef operations.

Causes of White Scours in Calves

There are several major causes of white scours in baby calves:

1. Bacterial Infections

Bacteria are one of the most common causes of white scours in calves. The main bacteria involved include:

  • Escherichia coli – A normal inhabitant of the intestinal tract that can cause illness if the wrong strains are present.
  • Salmonella – Another bacteria that may contaminate the calving area.
  • Clostridium perfringens – An anaerobic bacteria that produces toxins leading to diarrhea.

These bacteria can be passed from the cow to the calf during birth if the calving area is contaminated. They proliferate rapidly in the intestinal tract of the newborn calf, adhering to and damaging the intestinal lining. Some strains produce enterotoxins that cause excessive secretion of fluid into the intestinal lumen, resulting in diarrhea.

2. Viral Infections

Viruses are another major cause of scours in baby calves. The main viral culprits include:

  • Rotavirus – The most common viral cause of calf scours worldwide.
  • Coronavirus – Also a very common cause of diarrhea in calves.
  • Bovine viral diarrhea virus (BVDV) – Can cause immunosuppression and secondary bacterial infections.

Like bacteria, these viruses damage the intestinal lining, leading to impaired digestion and absorption of nutrients. They also stimulate secretory mechanisms, resulting in watery diarrhea.

3. Nutritional Factors

Nutrition can also play a role in neonatal calf scours. Feeding too much milk or milk replacer can overwhelm the digestive capabilities of the newborn calf, resulting in undigested material passing into the intestines. This draws in excessive water by osmosis, causing osmotic diarrhea. Other factors like sudden changes in diet may also contribute to cases of white scours in calves.

4. Parasitic Infections

While less common than viruses and bacteria, parasites like coccidia and Cryptosporidium species can sometimes be involved in outbreaks of calf diarrhea.

5. Other Factors

Some other factors that may contribute to calf scours include:

  • Stress – Such as difficult birth, poor sanitation, or extreme weather changes.
  • NSAIDs – Drugs like phenylbutazone given to the cow can increase risk.
  • Antibiotics – Which disrupt the normal gut microbiota.
  • Toxins – Such as mycotoxins in moldy feed.

In many cases of white scours, more than one factor is at play. Both viruses and bacteria may be involved, along with nutritional components. Understanding all the potential causes is important for prevention.

Risk Factors for Calf Scours

While the direct causes of neonatal calf scours are infectious agents and dietary issues, there are a number of factors that can increase the risk of disease outbreaks:

Calving Area Contamination

Calves are exposed to massive numbers of pathogens during the birthing process if the calving area is unclean. Bacteria, viruses, and parasites from manure and other sources quickly infect the newborn animal via the mouth and nose. Dirty calving pens or pastures greatly increase the odds of white scours.

Inadequate Colostrum Intake

Colostrum provides vital nutrients and antibodies to protect newborn calves against infectious diseases. Calves that do not ingest and absorb enough good quality colostrum in the first hours of life have a severely impaired immune system. They are far more susceptible to white scours and other illnesses.

Poor Ventilation

Proper ventilation removes respiratory pathogens, ammonia, dust, and other contaminants. Overcrowded, stuffy housing encourages buildup of infectious organisms. Good air exchange and space is especially important for young calves.


Chilling, difficult birth, poor nutrition, overcrowding, transportation, and other stressors negatively impact calf immunity. Stress makes calves more prone to white scours after exposure to infectious agents.

Co-mingling and Pen Movement

Bringing calves from multiple dams together and frequently mixing groups spreads pathogens. Keeping calves in the same hutch or pen during early life minimizes contagion. Movement and co-mingling of animals should be avoided in the first weeks.

Inappropriate Feeding

Overfeeding milk, rapidly changing milk/feed type, or irregular feeding schedules can upset the delicate digestion of newborn calves. This makes them more likely to develop nutritional scours.

Poor Hygiene

Dirty feeding equipment, calf housing, bedding, trailers, clothing, and hands of workers can all spread scours-causing organisms. Consistent hygiene practices are vital to block fecal-oral transmission routes.

Weather Extremes

Hot, cold, or rapidly fluctuating weather can stress calves and increase susceptibility to illness. Providing adequate shelter to moderate weather extremes reduces risk of sickness.


Younger calves under 3 weeks old are most vulnerable as their immune systems mature. However, white scours occasionally affects calves up to 2-3 months old.

Concurrent Infections

The immune-suppressing effects of one pathogen can make calves more prone to secondary infections. For example, calves infected with BVDV are much more likely to develop bacterial scours.

Clinical Signs of White Scours

Knowing the common signs of neonatal calf scours allows early detection and treatment. Here are the typical clinical features:

  • Profuse, watery diarrhea – Usually white/gray in color.
  • Depression, lethargy, weakness.
  • Dehydration – Sunken eyes, poor skin elasticity, dry gums.
  • Electrolyte imbalances – Seen on bloodwork.
  • Fever (may be present).
  • Inappetence or refusal to nurse.
  • Rapid weight loss.
  • Hypothermia.

Severe cases can progress to shock, coma, and even sudden death. Calves that appear otherwise healthy except for scours likely have an infectious cause. Systemically ill calves may have sepsis or underlying conditions like BVDV. Diagnostic testing can determine the exact cause(s).

Diagnosing Calf Scours

Definitively diagnosing the cause of white scours allows targeted treatment and prevention strategies. Diagnostic options include:

Fecal Analysis

Microscopic fecal exams, cultures, PCR testing, and ELISA kits can detect viral, bacterial, and parasitic pathogens. This pinpoints the source of the outbreak.


Post-mortem examination of calves that died from scours reveals intestinal changes and allows pathogen isolation. It provides very useful information.


Complete blood counts, blood chemistry, and serology can uncover secondary issues like sepsis, electrolyte disturbances, acidosis, and antibody status. These guide therapy.

Environmental Testing

Culturing samples from the calving area, housing, feed, bedding, etc. identifies infectious reservoirs. This facilitates cleaning strategies.

Isolating the organisms responsible for calf scours and identifying all contributing factors is key. Work closely with your veterinarian to obtain an accurate diagnosis.

Treatment of Calf Scours

Effective treatment of white scours in calves includes:

Fluid Therapy

Aggressive fluid treatment with oral or IV electrolyte solutions corrects dehydration, electrolyte disturbances, and acidosis. This rapidly stabilizes calves.


Feeding sufficient high-quality colostrum provides energy, antibodies, and other beneficial substances. It supports healing.

Milk Feeding

Continue milk or milk replacer feedings during scours outbreaks. The nutrients aid recovery without increasing severity or duration of diarrhea.

Anti-diarrheal Drugs

Intestinal absorbents like kaolin and pectin help Firm up stools. Other anti-diarrheals may be appropriate depending on the cause.


Antibiotics are indicated for systemic illness or confirmed bacterial infections. Choose targeted antibiotics based on culture results.


Anti-inflammatories like flunixin meglumine improve appetite and attitude in sick calves while providing pain relief.

Nutritional Support

Injected B vitamins, oral probiotics, and other nutritional supplements support intestinal health and recovery.


Separate scouring calves from healthy herd-mates to prevent further disease spread. Strict hygiene protocols are essential.

With intensive therapeutic management, the prognosis for calves with white scours is often good. However, delaying treatment raises mortality risk.

Prevention of Calf Scours

Preventing neonatal calf diarrhea is preferable to treating it. Recommended prevention strategies include:


  • Designate a clean calving area. Remove manure and disinfect regularly.
  • Disinfect calf housing between each animal.
  • Routinely clean feeding equipment like bottles, buckets, tubes.
  • Only provide clean, dry bedding.
  • Keep calving assistance supplies clean.

Colostrum Management

  • Ensure each calf gets at least 2-3 quarts of high quality colostrum immediately after birth.
  • Feed an additional 2 quarts of colostrum 12 hours after the first meal.
  • Test cows regularly for colostrum antibody levels.
  • Pasteurize colostrum to kill pathogens if herd health issues exist.


  • Avoid overcrowding in housing and calving areas.
  • Regularly maintain and check fans, curtains, ventilation systems.
  • Open shelters during mild weather to maximize natural airflow.


  • Feed good quality milk or replacer according to directions.
  • Make diet changes gradually.
  • Ensure adequate energy and nutrients for cows and calves.
  • Have feed tested for mycotoxins during storage problems or illness.


  • Vaccinate cows pre-calving against scours causing pathogens to increase colostral immunity.
  • Some farms vaccinate calves orally at 1-2 weeks old when scours an issue.
  • Vaccines for rota-corona, E. coli, C. perfringens, and other pathogens are available.

Stress reduction

  • Provide a clean, dry, draft-free calving area.
  • Ensure easy access to clean water and starter feed.
  • Avoid overcrowding and limit transportation stress.
  • Reduce temperature swings with proper housing.

Calf Management

  • Leave calves with dams for initial colostrum feeding if possible.
  • House calves individually during first weeks of life.
  • Group calves of similar ages after 3-4 weeks old.
  • All-in, all-out systems by age groups helps break disease cycles.


  • Use designated outerwear and footwear when working with calves.
  • Wash hands thoroughly before and after calf handling.
  • Clean and disinfect items like halters, brushes, feed tubs between pens.
  • Isolate sick calves immediately in hospital area.


  • Watch calves closely for early signs of sickness.
  • Record cases to identify patterns or ongoing issues.
  • Submit fecal samples during outbreaks to identify causes.
  • Necropsy dead calves when appropriate to determine pathogens.

Treatment protocols

  • Create written protocols for treating scouring calves.
  • Train all personnel to recognize and handle disease outbreaks.
  • Review protocol annually and update as needed.

Consistently implementing these preventive steps helps minimize white scours cases. However, occasional outbreaks still occur on most farms. Being prepared to treat affected calves reduces mortality.


Neonatal calf diarrhea is a complex, multifaceted disease process. Infectious agents, nutrition, stress, and environmental factors all contribute. Understanding the potential causes, clinical signs, diagnosis, treatment, and prevention of white scours is key to reducing the impact on calves. With proper colostrum management, housing, sanitation, vaccination, and biosecurity practices, white scours outbreaks can be minimized. However, prompt recognition and therapy of affected calves by veterinary professionals is still important for reducing mortality rates. Continued research on this costly issue for cattle producers will ultimately lead to new tools for controlling scours in baby calves.