Johne’s Disease in Cattle: Reducing Risk Through Good Biosecurity Practices  

Johne’s dsease (JD) is characterised by chronic wasting of the animal, eventually leading to death, the disease has been seen in cattle, sheep, goats, deer and camelids in Australia and is a notifiable disease across all states and territories. It is caused by a bacterium, Mycobacterium avium subsp. paratuberculosis. 

JD affects the animal’s intestines and causes thickening of the bowel wall that inhibits the animals’ ability to absorb nutrients from their food. This leads to the chronic wasting associated with the disease. In cattle specifically, common signs of JD present as diarrhoea and bottle jaw as well as weight loss despite good appetite. Signs of disease often appear after stressful events, such as calving, poor nutrition, or heavy milk production. 

Calves are likely to be exposed to the bacteria from infected adult cows through faeces, colostrum, and/or milk. Infection tends to occur in cattle less than 12 months of age, particularly in those less than three months old. It is possible for calves to become infected in utero, however, this is uncommon and only likely to occur if the pregnant cow is already showing signs of JD.  

Due to its long incubation period, clinical disease can remain unapparent until the affected animal is at least four or five years of age. While infected, the bacteria are shed in the cow’s manure, contaminating the environment before any clinical signs of the disease are apparent. However, animals showing clinical signs of JD remain the greatest contaminators of the environment. 

In order to mitigate the risk of spreading JD, it is imperative to develop and implement an effective farm biosecurity plan. By following a structured plan for biosecurity measures, the risk of disease exposure overall is decreased. For a helpful checklist regarding JD in cattle, visit the Animal Health Australia website for our ‘Biosecurity checklist – Johne’s Disease in Cattle’.   

Introduction of new stock on-farm is the main way that disease may enter a herd, so introducing low-risk stock onto the property with a management plan is the best prevention strategy. By only buying, selling or agisting high-assurance cattle such as those with a Johne’s Beef Assurance Score (J-BAS) of six or higher and insisting that the animals come with a National Cattle Heath Declaration, you can help reduce the risk of disease significantly.  

Make sure your herd is more resistant to disease through good nutrition and parasite control. Pay particular attention to animals that are failing to thrive – this could be an early warning sign of JD. Quarantine and investigate any animals showing signs of JD and report anything suspicious to your local vet for investigation. 

Vaccination of cattle with Silirum® should be considered in herds with JD present. This inactivated (killed) vaccine can be used in addition to disease management practices relating for JD. Producers wanting to use the vaccine in their cattle should consult with their vet, check with their state Department of Primary Industries (or equivalent) about any state/territory requirements surrounding administration, and follow the label requirements for permanent identification of vaccinates. 

For more information about JD, talk to your private or local government veterinarian or visit: https://animalhealthaustralia.com.au/johnes-disease/