Calf Scour 

Calf scour is a frustratingly common problem found on the majority of farms in the UK. As with other calf diseases, scour can prove very costly, however, control and prevention is very much within our reach. When investigating the cause of scour we must start at the beginning e.g. calving and the rearing system. There are many simple and cheap measures which can significantly reduce scour, which in-turn improves health and welfare without spending a lot on vaccination and vet costs. However, in some cases these measures may not be enough and a full investigation may be required.

calf scour


- Bacteria: Escherichia coli, Salmonella spp., Clostridium perfringens and other bacteria

Viruses: coronavirus, rotavirus, BVD virus, IBR virus

Protozoa: Cryptosporidium, coccidia

Yeasts and moulds



Most newborn calves are exposed to E.coli from the envirnment, especially when sanitation is marginal. Dung from healthy cows and scour from calves provides a source of E.coli for calves as young as 16 hours old. Death can occur from progressive, severe dehydration and also toxaemia. Calves suffering from septicaemia and meningitis can look very similar.


Salmonella, like E.coli produces a potent toxin. Antibiotic treatment can damage the salmonella organism, causing it to release the endotoxin. This toxin poisons the animal causing shock and severe illness. Treatment should therefore be aimed at combating the endotoxic shock. The source of infection can be from other cattle, birds, cats, rodents, the water supply or human carrier. Clinical signs include diarrhoea with blood and fibrin, depression and fever. Calves affected are usually 6 days old or more.

Clostridium perfringens

Clostridia infections are commonly known as enterotoxaemia. This type of disease is usually fatal and is associated with the release of toxins. The disease has an acute onset. Some calves may be lethargic, strain, show signs of colic or have some bloody diarrhoea, whereas others may die before any clinical signs are obvious. The disease is usually
associated with changes in feed, management practices or changes in weather conditions.


Rotavirus and Coronavirus

Both these viruses damage the lining of the small intestine which results in diarrhoea and dehydration. The damage caused by the viruses is often made worse by secondary bacterial infections which can lead to more fatalities. Calves as young as 1-2 days old can be affected by these viruses however, most infections occur when calves are around 1 week old or more. Death is usually caused by severe dehydration and also acidity in the blood. Giving intravenous fluids with bicarbonate counteracts both of these problems and can greatly improve survival rates.

Bovine Virus Diarrhea (BVD) Virus

The BVD virus can cause diarrhea and death in young calves. Diarrhea begins about 24 hours to three days after exposure and may persist for days or weeks. Erosions and ulcers on the tongue, lips, and in the mouth are the usual lesions found in the live calf. These lesions are
similar to those found in older animals affected with BVD virus. BVD virus also lowers the calf's immunity, leaving it susceptible to other diseases.

Protozoa / parasites


"Crypto" is a small protozoan parasite which sticks to the cells that line the small intestine and damage the absorptive surface. They can cause scour alone or are commonly found in mixed infections. Calves are usually infected from 1-3 wks of age. Crypto is transmissible to other animals and humans and therefore good hygiene is essential. Affected calves become weak and lethargic and have loose watery stools which may contain mucus, blood, undigested milk or bile. Straining to defecate may also be seen. Rehydration and the use of Halocur is the only treament available the moment. However secondary infections must be treated and supportive care is very important.


Is a fairly common condition, usually seen in weaned calves, although outbreaks have been reported in calves 3-4 weeks of age. Coccidiosis is caused by a single-celled parasite called Eimeria which attacks the cells of the gut lining. Scouring usually begins about 2 weeks after infection so by the time the calf is showing clinical signs, the damage to the gut lining has already been done.Other signs include: loss of appetite, stunted growth, dehydration, secondary infection, straining to pass faeces, rectal prolapse and occasionally death.


Nutritional scour

Nutritional scour can be caused by anything that disrupts the normal feeding habits such as a storm or the dam going off in search of new grass. When the calf eventually feeds it is overly hungry and the cow has more milk than usual. Consequently, the calf may over consume milk
leading to nutritional scours. This type of scour does not usually present a problem and the calf usually stays bright and alert.

1-4 days: 
E-coli most likely
1-3 weeks: 
Rotavirus, Coronavirus, Cryptosporidia 
2-6 weeks: 
Salmonella, Cocci

Control and prevention

  • Keeping the environment meticulously clean i.e. remove afterbirth and dung as soon as
  • possible, OR removing the calf from the calving environment immediately. 
  • COLOSTRUM at least 3 litres within the first 6 hours of life. Provides essential antibodies and energy. Sucking ideal but if any doubt use a stomach tube.
  • ISOLATE and treat any sick calves immediately.
  • CLEANLINESS of pens including feeders, water, passageways, pen dividers etc.
  • Samples of scour should be tested before any treatment is given where appropriate. If a
  • particular bug is found discuss the best plan of action with your vet.
  • Attention to detail, consistency and routines help ensure a healthy calf rearing system.
  • Set up Standard Operating Procedure's (S.O.P) appropriate for your set up (County Vets can help with this) or include a calf rearing plan in your
Example of S.O.P for a dairy farm
  • Ensure calving pen and calf pens are kept meticulously clean
  • Remove calf from dam immediatel after birth and ensure at least 3L colostrum within 6 hours of birth
  • Feed at least 2.5L milk, twice daily, preferably on a rising volume system until weaning
  • Clean and disinfect all feeding equipment daily
  • Ensure milk fed is at correct temperature, fed cleanly and consistently
  • DO NOT feed mastitic/antibiotic milk
  • DO NOT feed sourced or pooled colostrum
  • Ensure fresh clean water is available at all times
  • Ensure access to purpose made calf concentrate from 3-7 days and step up gradually
    until weaning when eating a minimum of 1.5-2kg concentrate/calf/day
  • Ensure access to forage (straw/hay) at all times, from 3-7 days fed from racks above
    floor level
  • Discourage eating of bedding as this is a major disease transmission risk
  • Clean and bed pens as often as necessary and at least daily


All sick calves should be immediately isolated and a sample of the faeces should be taken for analysis at your vets. Assessing the calf's hydration status is essential to determine what volume of fluids needs replaced. Look for sunken eyes and skin tenting and whether the calf is willing to suck. Scour results in loss of vital salts, fluid and energy necessary for the calf's survival. Treatment is directed at replacing these losses. Oral electrolyte solutions provide balanced sources of salts, fluids and energy, and can be fed up to six times a day. However, the energy they provide is not adequate, so continued feeding of normal milk or milk replacer is required. Ensure that milk feeds and electrolyte feeds are separated by at least 2 hours to allow normal milk clotting and digestion. Electrolytes should be given at body temperature and sick calves should be kept under a heat lamp to maintain body temperature. Collapsed calves need immediate veterinary attention as they may require intravenous fluids. If a particular bug is involved, vaccination may be required in the future e.g. Salmonella, Rotavirus, E.coli, and Coronavirus.