Calf scour and pneumonia share similar risk factors and the health of a calf is determined by the balance between its immunity levels and the level of infection it is exposed to.

How can you improve your calf’s immune system and reduce infection pressure?

Good colostrum intake is the first step to provide the newborn calf with good immunity. By following the 1-2-3 of colostrum management (the first feed of colostrum should be from the first milking, be given within two hours of birth and be of at least three litres), calves will get off to a good start.

After the first feed with colostrum, calves need a daily amount of at least 13% to 15% of their birth weight (eg six litres per day for a 40kg calf) of whole milk or a good-quality milk replacer.

Good hygiene is also critical as the calf is most vulnerable just after birth. The sources of infection for the newborn calf are the cow, calving environment and the calving itself. To reduce exposure, remove the calf from the calving area as soon as possible into a clean calf pen.

Calves need access to fresh, clean air (draught-free) and a well-bedded lying area for warmth. Young calves spend about 80% of their time lying down. Wet or insufficient bedding result in calves getting “chills”.

The optimal air temperature in the calf house, for calves under three weeks is 15°C to 20°C and low air temperatures suppress their immune system. Ideally, calf pens should be cleaned out between calves or generously topped up with straw. They should be dry enough that your knees don’t get wet when you kneel down.

As the calving season progresses, infection tends to build up. It is also important to keep feeding equipment clean.

Stressors like weaning, low temperatures and disbudding reduce the ability of the immune system to fight infection. To minimise stress for calves at disbudding, ensure it does not coincide with other stressful events and that proper pain relief is used.

Scour and how to prevent it

Scour results from a damaged intestine leading to a loss in function, causing the calf to lose fluids.

The initial damage is caused by bugs such as, E coli (in calves under five days of age), cryptosporidia, rotavirus, coronavirus, salmonella and coccidia (in calves older than three weeks).


A diagnosis is needed to develop the most effective treatment plan. Rapid faecal test kits are available for immediate diagnosis. Speak to your veterinary practitioner because as infection builds it can spread rapidly.

Scour is rarely due to nutritional reasons alone (overfeeding, poor-quality milk replacer) and generally has an underlying infectious cause, although calves fed high volumes of milk will have looser faeces. Be aware that cryptosporidium and salmonella can be spread to vulnerable humans from infected calves.


Isolating the calf helps prevent spread of infection and gives it a better chance to recover. Fluids that are lost with scour should be replaced with an additional four litres electrolytes per day, independent of the milk feeds (at lunchtime and late in the evening) while the calf is scouring.

Electrolytes can be given by stomach tube if the calf refuses or is unable to drink. Continuing to feed milk or milk replacer does not worsen scour and helps heal the intestine.

Milk or milk replacer should not be stomach-tubed as this will lead to the buildup of acids in the rumen and damage the ruminal wall. Contact your veterinary practitioner if a calf refuses to drink several feeds in one day, is very weak, eyes are sunken or if its temperature is abnormal (normal range is 38.5 C to 39.5°C)

Antibiotics do not work against the parasites and viruses that cause many calf scours so antibiotics should not be used unless instructed by a veterinary practitioner.

There are drugs available, with a veterinary prescription, to treat cryptosporidiosis which may reduce the severity of disease if given early in the course of infection. However, using these products on their own will not solve a cryptosporidia problem if general hygiene is not also improved.

With calf scour vaccines, the cows are vaccinated with a single injection at least three weeks before calving, to enhance the colostrum with antibodies against rotavirus, coronavirus and E coli and the vaccine gives 12 weeks of protection. These vaccinations are only of benefit if proper colostrum procedures are followed.

Scour: key points

  • Continued milk feeding speeds up the recovery of the scouring calf.
  • Feeding electrolytes is the most important treatment for the scouring calf.
  • If you have an ongoing serious problem with calf scours, look into your colostrum, nutrition and hygiene management and seek a veterinary diagnosis.
  • Pneumonia in calves

    Pneumonia in calves is often referred to as a “multifactorial disease” meaning that infectious agents, environmental and management factors all contribute to the development of disease. Calves that suffer repeated and/or severe bouts of pneumonia may end up stunted for life.

    Causes and signs

    Viruses suppress the calf’s immune system, making it easier for bacteria to invade the lungs but bacteria can also cause pneumonia on their own.

    Early diagnosis is essential for successful treatment. Initial signs of pneumonia may be non-specific and include reduced feed intake, being “off-form”, fever (over 39.5°C), coughing, panting, watery discharge from the nose and eyes.

    Advanced signs of pneumonia include pus-like nasal discharge, and severe respiratory distress and these calves may not be curable.

    Careful observation of calves when resting, in addition to observing at feeding, is required to pick up these signs. Discuss this with your veterinary practitioner before undertaking any treatment, as they may need to undertake diagnostic tests.

    In addition, treatment should be discussed with your veterinary practitioner as antibiotics are ineffective against viral infections. However, where bacterial involvement is suspected, antibiotic treatment is required. If antibiotics are not used appropriately (ie correct drug for the disease at the correct dosage for the correct duration), there is an increased risk of creating bacteria that are resistant to further treatment.

    Treatment of calves with oral antibiotics is not recommended as diseased calves often have a reduced appetite and will not receive the correct dose.

    Non-steroidal anti-inflammatory drugs (NSAIDs) can be used in combination with antibiotics to help reduce fever, pain and inflammation in the lungs.

    Vaccination protocols

    Vaccinations, in conjunction with efforts to reduce other risk factors involved, are important in pneumonia prevention and vaccination protocols should be tailored for each farm under veterinary advice.

    Vaccination reduces the severity of disease and shedding of the pathogen thereby reducing the infection pressure on surrounding animals.

    Vaccination must be completed before the risk period. Immunity begins four days after most intra-nasal vaccines and approximately three weeks after the second dose for some injectable vaccines.

    If calf pneumonia is a recurring problem on a dairy farm, housing and husbandry factors should be thoroughly investigated because a holistic approach is needed to prevent and control pneumonia.

    Pneumonia: key points

  • Prevention of pneumonia is better than treating outbreaks.
  • If calves are not treated early enough and for long enough with the correct treatment, the calf may relapse with recurrent bouts of pneumonia.
  • Calves should always have access to fresh air, free of draughts and a good dry, well-bedded lying area.
  • Avoid putting ill or stunted older calves into a group of younger calves “to bring them on”.
  • Sharing airspace with adult or bought in animals is a big risk for pneumonia in calves.
  • Ensure vaccines are stored and used in accordance with the manufacturer’s recommendations.