Of all the animal health issues that can affect dairy and beef farms, dealing with sick calves is up there with being the worst.

Not only does a disease outbreak in calves increase the likelihood of mortality, it also puts a huge burden on the farmers’ time treating sick calves.

It also adds to costs, but I would say that the mental turmoil of seeing young calves suffer is probably the biggest cost that the farmer has to bear.

The old adage that prevention is better than cure really is true when it comes to calf health. Two of the biggest calf diseases in Ireland are pneumonia and scour.

Keeping these diseases out of the farm will go a long way towards ensuring a successful season.


Pneumonia is a common disease among young calves and cattle. While the direct causes of pneumonia are varied, it’s fair to say that it tends to strike where the calf’s immune system is low.

An example of lungs damaged by pneumonia.
The strength of the immune system is governed by the calf’s feeding regime, housing conditions and colostrum management.

Weaknesses in one or more of these areas can weaken the calf’s immune system and leave it open to contracting an infection.


Pneumonia can be caused by a virus or bacteria. A typical case will see a virus attack the calf’s immune system, leaving the door open for bacteria to attack the lungs.

Damage to the lungs can be severe and permanent.

Even if the calf recovers from pneumonia they can often be stunted for life.

According to Animal Health Ireland, the viruses and bacteria that cause pneumonia are also present in healthy calves, which suggests that calves that get pneumonia have less immunity, for whatever reason, to the disease.

Symptoms of pneumonia

The early symptoms of pneumonia are a calf being off-form or dull looking. Very often, they will have reduced appetite or won’t visit the computerised calf feeder as often and, as a result, will look a bit “hollow”.

Sick calves will have a high temperature, above 39.50C. Other classic symptoms of pneumonia are faster breathing rate, coughing or discharge from nose and mouth.

Early treatment of calves showing signs of pneumonia is absolutely critical for a successful outcome.

Isolate sick calves immediately and talk to your vet about the best treatments. Antibiotics won’t cure a virus but, often, there is bacteria in the lungs for which antibiotics should be effective against, if given in time.

Depending on the case, many vets may prescribe an anti-inflammatory drug along with the antibiotics to reduce pain, fever and inflammation in the lungs.

Where a calf makes a good recovery it’s important to keep treating the animal for as long as is prescribed, because if some of the harmful bacteria survives it can start growing again. That is why a calf that got pneumonia once can often get it again.

Vaccines are effective at reducing some of the viral diseases that cause pneumonia such as IBR, RSV and P13. Vaccines can be administered to young calves in different ways depending on the risks on the farm.


Scour is another big disease that affects young calves. It is caused by a parasite or a virus attacking and damaging the gut of the calf.

Damage to the gut prevents the nutrients in the milk from being absorbed properly and so they pass through the calf, hence very loose and watery faeces are the main symptoms of scour.

Samples of scour should be tested to check the cause.

The common causes of scour are cryptosporidium and rotavirus in younger calves and coccidiosis in older calves. These are really nasty diseases that make calves very sick very quickly. They can also spread quickly, so an initial small number of cases should be treated very seriously as the disease can spiral out of control. Not only that, but cryptosporidium is a zoonotic disease that can be transferred to people, especially those with low immunity.

So it’s important to know what type of scour you’re dealing with although, in many cases, there will be more than one active agent in an outbreak.

Treatment for scour revolves around replacing the fluids lost by the scour. This involves giving multiple feeds of electrolytes throughout the day in addition to the milk.

It’s important not to stop feeding milk just because the calf is scouring. Isolate the calf as soon as it begins to show signs of scour.

Antibiotics will not be effective at curing scour but a vet may prescribe antibiotics if the calf is very sick.

Isolate sick calves from healthy animals.

Prevention is based on reducing pressure on the calf by making sure it has received enough colostrum at birth, has a clean, dry lie and that hygiene of feeding equipment is excellent.

Vaccines are available for rotavirus but for this to be effective calves should be fed transition milk for at least the first 10 days.