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Further information on health conditions that may cause scours (diarrhoea) in cattle.


Conditions that cause loose or watery manure, often passed at frequent intervals, which may have a bad odour and/or an unusual appearance. What class of stock is affected?

Adult cattle

Young stock

  • Focus on prevention for calves that thrive
  • Keep the calving environment clean
  • Remove calves from their dams early
  • Develop a disease prevention program and treatment protocols - train your staff well
  • Implement the 3 Step Calf Plan for the control of Johne's disease
  • Manage manure build-up to keep pathogen numbers down
  • Handle sick calves carefully to avoid contaminating healthy calves
  • If necessary, use humane slaughter techniques

More information

Rearing Healthy Calves: Focus on prevention for calves that thrive (PDF, 880KB)

This document helps you with disease prevention strategies, including good calving pre-care, minimising contact with manure, and effective cleaning.

  • Copy Link Acute acidosis


    What to look for - ranges from serious acute disease to milder chronic form.

    Acute acidosis

    • Usually within 1 day of carbohydrate overload
    • May stop eating
    • May appear depressed
    • May be unstable if standing
    • Rumen is often distended (on left side)
    • Tapping left flank may produce splashing sounds
    • May have profuse diarrhoea with an offensive smell
    • May become dehydrated, lie down, and without prompt treatment, are likely to die

    Chronic acidosis

    • Usually a herd problem
    • Vague clinical signs Loss of appetite
    • Intermittent diarrhoea
    • Lower milk production
    • Depression


    Excess amounts of carbohydrate-rich foods such as grains or fruit. Rumen function is overloaded leading to increased acid in the rumen. Milder forms have a slower onset, but if not managed can lead to long term changes to the rumen.

    Animals likely to be affected

    Often seen in cows in early lactation. Typically seen after calving, especially in cows that have been fed on pasture during the dry period and the rumen has not had time to adapt to concentrate feeds.

    Other diseases with similar signs

    Confirming the diagnosis

    • Recent increase in consumption of grain or fruit
    • Test rumen fluid acidity (pH)


    Serious cases of acidosis need rapid treatment. In severe cases your vet can operate to remove the rumen contents and provide other supportive treatments to help get the rumen operating again and prevent infection.

    Less severe cases may respond to treatment with magnesium products given by stomach tube. Afterwards it is important to feed good quality hay and ensure that animals do not have access to water until the next day.

    Animals that have mild acidosis should be fed good quality hay and reduced amounts of concentrates. Watch them closely to ensure that any animals that are not improving can be treated more intensively.

    Risk factors

    • High carbohydrate feeds are not stored securely
    • Cattle introduced rapidly to diets containing high proportion of concentrates


    When introducing cattle to concentrates monitor them closely and check the consistency of their manure.

  • Copy Link Bovine Johne s Disease

    Bovine Johne's Disease

    Bovine Johne's Disease (BJD) is a chronic, incurable disease of adult cattle caused by the bacteria Mycobacterium paratuberculosis. Symptoms include diarrhoea, reduced milk production, weight loss and eventually death. The disease is mainly spread through ingestion of contaminated faeces. Infection is usually acquired in calfhood but generally no clinical signs are seen until animals are at least four years old. It is difficult to reliably detect infection in live animals, particularly in the early stages of the disease.

    For more information go to our Bovine Johne's section.

  • Copy Link Coccidiosis


    What to look for

    • Mild to serious diarrhoea in calves
    • In serious cases diarrhoea contains blood and, after a short period, smears their rear end
    • Animals look listless and may become dehydrated, go off their feed and have a rough coat
    • Recovery can be slow, especially if the affected calves stay in the same area and are continually being re-infected

    Cause -“ a protozoan infection

    • Most often caused by Eimeria zuernii or Eimeria bovis

    Animals likely to be affected

    Usually young animals 3-8 months of age

    Other diseases with similar signs

    Other infectious causes of scours in calves:
    Salmonella infection
    Mucosal disease
    Cryptosporidium infection
    Intestinal parasites
    Rotavirus infection
    E coli infection

    Confirming the diagnosis

    Laboratory test for coccidia in faeces. If necessary confirm the diagnosis by conducting a post-mortem examination and observing the characteristic changes to the gut wall.

    Spread of the disease

    Coccidia are picked up while feeding and infect the cells that line the calf's intestine. Large numbers of coccidia are then shed in the faeces. Environmental contamination can build up, so that animals can be constantly re-infected in areas that are continuously used for young stock, especially if stocking rates are high. The level of contamination is greater if there are moist conditions that favour survival of organisms in the environment.

    Risks to people

    No risks for people but other causes of diarrhoea in calves (such as salmonella infection) may cause disease in people.


    The first step is to separate the sick animals. Other animals in the group should be moved from the contaminated area. Appropriate treatment can be prescribed by your vet. If animals are dehydrated, they also need to be supported with electrolyte solutions.

    When contamination has built up, a short course of a coccidiostat may be needed to break the cycle of infection before moving the animals on to safer pastures. Coccidiostats can be included in calf feeds. This should be planned with your vet to choose the most effective drugs, optimise the effect and reduce costs.

    It is not necessary to aim for complete freedom from contact with the causative organisms as some contact allows the animals to build up immunity - the challenge is to avoid a level of infection that will cause disease.

    Risk factors

    • Build-up of high levels of organisms in yards and paddocks used by young stock. If possible, young animals should be rotated around a series of paddocks that avoid any contact with adult animals (a practice also recommended for control of Johne's disease).
    • Stockfeeds containing anti-coccidial drugs are suddenly discontinued

  • Copy Link Roundworms


    Clinical signs

    • Ill thrift, weight loss
    • Heavy infections cause a profuse watery scour which can lead to dehydration
    • In yearlings and adult cattle a heavy infestation with Ostertagia roundworms can damage the fourth stomach resulting in loss of weight, reduced milk production and diarrhoea.


    There are 3 types of roundworm found in Australian dairy cattle (Ostertagia ostertagia; Trichostrongylus axei and Cooperia oncophora). Most animals carry some roundworms, but tend to develop immunity as they grow older and show few clinical signs if they are lightly infected.

    Roundworms produce huge numbers of eggs which are passed out in cow manure and hatch into tiny larvae. Dry, hot conditions destroy many larvae while cold weather slows down their life cycle. The worm larvae go through several life stages while living on grass, soil and in pats of cow manure, before becoming infective. When eaten by cows, these larvae develop into adult worms and find their way to the stomach and intestines.

    Animals likely to be affected

    Recently weaned calves grazing heavily contaminated paddocks. Occasionally worm numbers build up in adult animals and may cause type 1 or type 2 ostertagiosis, which usually affects only a small proportion of a mob.

    Other diseases with similar signs

    Other causes of diarrhoea in adult cattle and yearlings, including coccidiosis, yersiniosis, salmonellosis, BJD, BVD.

    Confirming the diagnosis

    Worm egg counts on manure. Laboratory tests to rule out other causes of scours.

    Risks to people

    Cattle roundworms do not pose any risks to people.


    Roundworms can be treated with 3 types of cattle drench, some of which are formulated as pour-on applications. Regular use of the same drench has the potential to select worms that are resistant, so drenches should be used strategically.

    Risk factors

    - Grazing recently weaned cattle on pastures that are heavily contaminated with infective worm larvae
    - Short intervals between grazing episodes
    - Cold wet conditions


    The aim is to expose stock to a low level of roundworms that do not harm them while allowing immunity to develop. Use grazing management to avoid the build-up of very high numbers of infective worm larvae on pastures. Identify safer paddocks for young vulnerable calves, such as those used for cutting hay or silage.

    If grazing programs are not sufficient to control roundworms, use strategic drenching to reduce impact on vulnerable animals. Ask your vet to help plan a drenching program to ensure that costs are minimised, benefits are maximised and there is no build-up of resistance to drenches.

  • Copy Link Salmonellosis


    What to look for

    • Fever and depression
    • Foul smelling diarrhoea which may contain shreds of intestinal lining and/or blood
    • Rapid dehydration, weight loss
    • High death rate in calves
    • Abortion in pregnant animals

    Cause -“ a bacterial infection (various Salmonella species)

    Salmonella infections occur in a huge range of animals, birds and reptiles, and can move from one animal species to another. It is often carried in the gut of animals and birds without causing disease. Contamination of feed stuffs and water with faecal material can cause large scale outbreaks. Outbreaks are sometimes related to stresses such as transport, temporary deprivation of feed or sudden onset of extreme weather events. The number of infected animals can vary from isolated cases to outbreaks involving large numbers of animals.

    Animals likely to be affected

    Most commonly seen in young calves (2-6 weeks of age) and lactating cows with high milk production.

    Other diseases with similar signs - other causes of severe diarrhoea

    In young animals (see Chapter 7 of Rearing Healthy Calves) these diseases include infection with rotavirus, cryptosporidia, Escherichia coli, coccidiosis, bovine viral diarrhoea, roundworms or Yersiniosis. In older animals you also need to consider conditions caused by trace element deficiencies (copper or selenium), plant toxicities or poisonings.

    Confirming the diagnosis

    The diagnosis is based on clinical examination, a thorough history of an outbreak and laboratory testing. Farmers that have experienced an outbreak of salmonellosis in adult cattle will be able to quickly recognise the clinical signs and should seek early assistance.

    Spread of the disease

    Salmonella can spread by movement of animals or by spreading of effluent on pastures. It can persist for months in a cool and moist environment and contamination can build up relatively quickly when an animal develops diarrhoea and excretes huge numbers of the organism. Prompt treatment and isolation of sick animals is therefore paramount.

    Risks to people

    Salmonella is one of the most important causes of gastroenteritis in people. Most cases occur after consumption of contaminated food but infection can be contracted directly from animals especially if they have clinical salmonellosis. In these circumstances it is very important to reduce exposure as much as possible and to practice high levels of personal hygiene. Do not drink unpasteurised milk from cows that may be infected with Salmonella.


    Cows and calves with serious cases of salmonellosis will deteriorate very quickly. Call your vet as quickly as possible to get a diagnosis and start appropriate treatment. They require prompt treatment with antibiotics and supporting therapy to save lives and slow spread of the disease.

    Risk factors

    • introducing animals that have been mixed with animals of unknown origin, especially in stressful environments such as saleyards
    • introducing animals to the main herd before there has been time for any sick animals to identified
    • contact between susceptible animals and effluent on the home property or from neighbours
    • mixing agisted animals with other animals or transporting them in dirty trucks
    • rodent infestations


    A vaccine is available that cattle protects against the most important strains of salmonella found in Australia. It requires two doses about a month apart with an annual booster. Passive immunity in young calves can be boosted by feeding an adequate amount of colostrum from vaccinated cows in the first few hours of life.


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