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Diarrhoea in young animals

Harry Edwards

Diarrhoea or calf scour can be a major cause of poor growth and calf mortality.


Healthy Calve


The incidence and severity of disease is highly dependent upon the level of colostral protection that a calf receives within the first six hours of life. It is generally recommended that calves receive three litres within the first 2 hours of life.

If calf diarrhoea, joint infections, meningitis and septicaemia have become a problem in young calves on your farm it would prove very worthwhile checking their immune status by means of a simple and inexpensive blood test (measurement of total plasma protein concentration) undertaken by your veterinary surgeon.

The most important causes of calf diarrhoea are caused by viruses such as rota- and corona-viruses, infections caused by Salmonella species (such as Salmonella dublin and Salmonella typhimurium) , E. coli can be a major problem, as can Cryptosporidiosis in housed dairy calves.


For an accurate diagnosis, please consult your local veterinarian and / or your State veterinarian.


  1. Fluid therapy is the most effective treatment strategy.
  2. Parenteral antibiotics should be used to control concurrent infections, e.g. navel ill and calf diphtheria.
  3. As with all animal diseases prevention is better than cure and an effective veterinary herd health plan is essential to maintain health and prevent costly diseases.
  4. Vaccines are available against the most important infectious causes of calf diarrhoea but a prevention strategy will only work if calves receive adequate volumes of good quality colostrum within few hours of birth.


Rotavirus infection

Rotavirus infection is a common cause of diarrhoea in young dairy calves. Calves are most commonly affected at 8 to 14 days old when there is an acute onset of diarrhoea with the passage of very watery yellow/green faeces. Infection may be acquired in the calving accommodation then spread between young calves in the calf house by direct contact. Typical early signs include a reluctance to stand and drink, mild depression and salivation. The calf becomes dehydrated with sunken eyes and tight and inelastic skin; recumbency soon follows.

The diarrhoeic calf should be isolated in a dry, well-bedded pen. 1-2 litres of oral electrolyte are given 4 to 8 times daily. Intravenous fluids administered by a veterinary surgeon are essential in dehydrated calves that are unable to stand unaided.

Parenteral antibiotics should be used to control concurrent infections, e.g. navel ill and calf diphtheria. Return to a milk diet should be a complete change and not diluted with electrolyte solution. Alternate milk and electrolyte solution should be fed every four hours.

Annual vaccination of the dam with a combined rotavirus, coronavirus and K99 combined vaccine will help prevent disease in the newborn calf following colostrum feeding for the first two weeks of life.

Since protection of calves depends on the physical presence of passively acquired antibodies within the gut, calves must receive adequate colostrum from their dams. Optimal results will be obtained if a whole herd cow vaccination policy is adopted. This will ensure that the level of infection and consequent virus excretion is kept to a minimum and consequently, the overall level of disease challenge on the farm is kept to a minimum.

Coronavirus diarrhoea

Outbreaks of calf coronavirus diarrhoea are similar to, or more severe than, those observed for rotavirus infection. Fortunately, coronavirus infection is much less common than rotavirus.

Treatment and prevention of coronavirus infection is as outlined above for rotavirus.

Enterotoxigenic E. coli

In calves this term is used to refer to strains of the bacterium E. coli possessing the K99 antigen. Recent surveys show the incidence of K99 E. coli to be low in dairy herds. The disease characteristically affects calves aged 1-3 days old when there is sudden onset of profuse yellow/white diarrhoea causing rapid and severe dehydration. The calf quickly becomes recumbent. Accumulation of fluid in the abomasum and intestines gives the abdomen a bloated appearance. Disease would typically follow introduction of infection into the herd with contamination of the calving environment and infection of newborn calves.

Prevention of Enterotoxigenic E. coli infection is as outlined above for rotavirus and coronavirus using a combined vaccine and ensuring passive antibody transfer in colostrum.


Cryptosporidiosis is not a major problem in dairy calves housed in individual pens but infection can rapidly build-up in group pens fed by automatic feeders where newborn calves are constantly added to the group.

Diarrhoea is caused by the physical loss of absorptive area of the small intestine and exacerbates the viral infections described above. There is profuse yellow/green diarrhoea with much mucus present. There is only mild dehydration but the calf rapidly loses condition over 2-5 days and has a dull tucked-up appearance. Whilst morbidity is high, the mortality rate in uncomplicated cases is usually low.

In uncomplicated cases ensure that the scouring calf is properly hydrated and use oral electrolyte solutions as necessary. Cryptosporidiosis is a zoonotic disease (can affect man).


Salmonella species, such as Salmonella Dublin and Salmonella typhimurium, can cause severe diarrhoea with the presence of blood and mucosal casts which may result in death. More often, Salmonella infections of young calves cause joint and bone infections and severe pneumonia which proves very difficult to treat. Identification of Salmonella infections necessitates detailed veterinary investigation.

Prevention and control of calf diseases caused by certain Salmonella spp. can be achieved by appropriate vaccination of the dam with colostral transfer of protective antibodies.



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