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Screening, diagnosis and treatment of diarrhea in dairy calves

Theresa Ollivett Published on 22 May 2015

Neonatal calf diarrhea is a concern on many dairy farms and is caused by a combination of nutritional and infectious problems. The bacteria E. coli can cause diarrhea within the first couple days of life.

After that point, rotavirus, coronavirus and the protozoa cryptosporidium contribute most to the diagnoses of diarrhea in 1-week-old to 3-week-old calves. Salmonella spp., another bacteria, rears its ugly head at any point.



Clostridium is a less common cause of bacterial diarrhea. It can certainly damage the intestines of calves, but diarrhea is not a common sign. Although most pathogens are present at some level on all dairies, having a specific diagnosis can help tailor vaccination protocols and inform employees about the potential for human health risks.

Preventing diarrhea is key, and calf management will always trump the perfect treatment plan. Good calf management should include the following elements:

  • Provide a clean, dry well-ventilated environment in the calving area and in calf housing.
  • Remove the calf from the calving area within 10 minutes or before standing attempts begin.
  • Provide adequate colostrum immunity, high-quality nutrition and consistent feeding practices.
  • Adhere to an appropriately designed vaccination plan.

Following these protocols will minimize the number of calves that need to be treated, saving time, energy and expenses.

That said, calves will develop diarrhea. Work with your veterinarian to develop a protocol for screening and treating calves with diarrhea. Screening methods vary depending on the housing and feeding systems in place. In individual housing systems, the best opportunity to identify calves with abnormal manure, appetite and attitude is around or just after feeding time.

Calf caregivers should be trained to look for these abnormalities and mark the stall or write the calf ID down for further examination. In group housing systems, calf caregivers should purposefully scan all calves less than 3 weeks old for abnormal manure, appetite and attitude (depression, prolonged standing, arched back, hair standing on end) twice a day.


Record each case of diarrhea in a systematic manner. This is the only way to accurately track changes in how often diarrhea is occurring. Recording mild cases that are not treated serves a purpose and should be considered. This might help identify when and where problems begin.

Monitoring items such as the number of new cases per month and the age of onset will help determine the severity and in which age group the problem is occurring. Often, calves with diarrhea develop respiratory problems within the next couple of weeks. Reducing the occurrence of diarrhea will reduce the occurrence of respiratory disease.

When too many calves are suffering from diarrhea, either in general or as an outbreak, some investigative measures should be taken to identify the pathogen involved to help guide treatment and prevention. Dr. Sheila McGuirk at University of Wisconsin – Madison suggests checking fecal samples from six calves for potential pathogens.

It is of concern when more than two of six samples are positive for rotavirus, coronavirus or cryptosporidium. Any calves testing positive for salmonella should be cause for concern. When testing calves for diarrhea pathogens, check both the calves with diarrhea as well as those with normal manure in order to assess whether the organism is contributing to the problem.

It is important to collect fresh feces from calves that have not been treated recently with antibiotics. Other management factors should be investigated but are outside the scope of this article.

Severe diarrhea may double the fluid requirements for a calf. In addition to water, electrolytes and buffers are also lost. Acidosis may develop when sufficient buffer is lost through the diarrhea or excessive acids are produced either secondary to the dehydration or through abnormal bacterial fermentation within the gut. Acidosis causes depression and can lead to an inability to stand.


Preventing and correcting fluid-, electrolyte- and acid-base imbalances through appropriate hydration are the primary goals of treatment for the scouring calf. Oral electrolytes are best for calves that are standing and have a good suckle.

Oral electrolytes are not all created equal, and it is very important that you work with your veterinarian to find the electrolyte that has appropriate levels of the four key ingredients: sodium, glucose, an alkalinizing agent and supplemental energy. Intravenous fluid therapy is necessary when a calf is unwilling to suck or will not stand.

In general, do not restrict milk or milk replacer to calves with diarrhea. There is good evidence that calves with cryptosporidium continue to gain weight despite significant diarrhea when they are allowed to consume large volumes of milk replacer.

Malnutrition becomes a big concern, especially during cold weather, when calves are deprived of milk during a case of scours. It is extremely important to not force-feed milk or milk replacer to calves that are inappetant. Force-feeding calves without a suckle can worsen acidosis, prolong recovery and increase the risk of death.

Antibiotics are not needed for every case of calf diarrhea. Some controversy exists, but the general consensus is to reserve antibiotics for calves that are sick with their diarrhea (not eating, have a fever, diarrhea is bloody, have pneumonia, navel infection or other problems). If the only problem is that the calf is sick with its diarrhea, a three-day course of antibiotics should be sufficient.

Talk with your veterinarian about choosing the proper antibiotic, which should target specific gram-negative bacteria and be used according to appropriate regulatory guidelines. Overuse of antibiotics may disrupt the normal flora of the calf’s gastrointestinal tract, causing more diarrhea, so another approach to managing calf diarrhea is to feed prebiotics and probiotics to improve the intestinal environment.

In summary, screening for neonatal calf diarrhea is an important first step in early, effective treatment. Treatments should primarily consist of supportive care involving replacing lost fluid, electrolytes and buffers. Antibiotics should only be used in select cases. Recording findings will help guide management decisions in the future and will determine if treatment protocols are successful. PD

This article was originally writtenby the author for Agri-Plastics.

theresa ollivett

Theresa Ollivett
Assistant Professor
Food Animal Production Medicine
University of Wisconsin– Madison