Johne's disease (JD) is a serious disease of cattle, sheep, goats, alpaca, llama, camels and deer. It produces chronic diarrhoea or ill thrift, leading to emaciation and eventually death.
Young animals are infected either when suckling their dam or grazing contaminated pasture. The bacteria lives and multiplies in the small intestine and lymph nodes and is shed in the faeces. Clinical signs do not usually become apparent for a couple of years.
Clinical signs are a gradual loss of bodyweight despite a normal appetite. During a period of several weeks, diarrhoea develops in cattle, but not routinely in sheep. Animals showing signs of disease will inevitably die.
Testing is complex and can take 12 weeks or longer if complications arise. A range of tests may be included in confirming a diagnosis. Blood and faecal samples are collected from live animals to test for JD. The blood test is rapid but unreliable as an individual animal test because false positives and negatives can occur. The blood test is suitable only as a herd test.
Faecal culture provides a reliable result but the test takes up to three months to complete. Tissue samples of the small intestine can be collected at autopsy for histological examination and culture.
National Johne's Disease Control Program (NJDCP) has been in place in Australia since 1996. Specific control and management plans are available for OJD and BJD. The Australian Johne's Disease Market Assurance Program, an audited quality assurance program, incorporates animal health risk assessment, testing and movement controls. It provides a source of low-risk animals for the various industry sectors in the jurisdictions where the disease is known to occur.
Pestivirus (Bovine Viral Diarrhoea virus)
This virus has become more commonly recognized on both beef and dairy cattle properties. It can cause significant loss in production as it causes infertility, abortions, birth of weak calves, and an illthrift with immune suppression. It is endemic in some areas of Queensland. Our cattle veterinarians can talk you through the diagnosis and prevention or management of this disease.
Vibriosis is a venereal disease of cattle causing infertility, returns to oestrus and delayed conception (usually by 3-4 months) and abortions. It is usually easily controlled by vaccination of bulls which catch it by covering cows that have been infected by another bull or within in the bull herd. It has become more commonly recognized now and many breeders vaccinate for this disease.
Three Day Sickness (Bovine Ephemeral Fever)
“Three Day” is a disease affecting the ability of infected cattle to get up and walk. Infected cattle usually have a fever and are unwell, however large cattle are more severely affected (bullocks and fat steers) because once they are down and unable to get up, the damage to muscles and nerves is compounded by their weight. It is caused by a virus carried by mosquitoes and midges, which is why graziers tend to see it more in the warmer months. The vaccine can greatly reduce the mortality and improve the recovery rate of infected cattle.
Leptospirosis and Clostridial disease
Leptospirosis is a bacterial disease, which can cause abortions, mastitis, liver and kidney disease and reduced milk production in cattle. It is also carried by rodents and pigs and can be transmitted to humans. Vaccination is only available for pigs and cattle. Even if you don’t vaccinate against leptospirosis for benefits in productivity, it may be worth considering from a human health perspective.
Combined Leptospirosis/Clostridial vaccine is available. Clostridial vaccinations, such as 5-in-1, target Tetanus, Pulpy Kidney, Black Disease, Blackleg Disease and Malignant Oedema.