FAQ - Johne's Disease
Is a 3 metre gap between my herd and neighbouring herds necessary?
This is not a requirement for the Johne’s disease programme
I share water courses with other herds – does that prevent my herd from gaining risk level 1 or 2 status?
No, however there could be a risk if infected cattle were grazing upstream and contaminating water courses. Ideally water should be provided from piped sources in water troughs.
Are cattle susceptible to getting infected with Johne’s disease all of their life?
Those that are most susceptible to infection are young calves up to six months old. They become less susceptible to infection with age. Adult cattle are relatively resistant to becoming infected. Calves can be born infected if their dam was infected. The chances of this occurring depends on whether or not the cow was showing clinical signs of Johne’s disease. If she was, there is a 25-40% chance of the calf being born infected. Whereas if she is positive on testing but not yet showing clinical signs, then the chances of the calf being born infected are around 1 in 10. In either case there is a high risk that the calf will become infected after birth due to exposure to its dam’s faeces and the risk of acquiring infection from her colostrum and milk. In dairy herds, removing calves from their dams as soon as possible after birth and not feeding colostrum or milk from Johne’s positive cows to calves are important aspects of a control programme in infected herds.
The disease has a long incubation period of usually at least a couple of years but more commonly three to five years.
Signs of disease (wasting and diarrhoea) are most commonly seen in cattle aged 3-5 years old but it is becoming increasingly common to see two year old animals, and occasionally younger, showing signs of Johne’s disease. These cases in young animals are likely to have occurred due to a very heavy challenge as a young calf or due to them being born already infected.
Johne’s disease Testing
What do I need to do for the first herd test?
Test all cattle two years of age and older. Evidence of a Johne’s disease health plan being in place, with the mandatory elements of the control programme being followed, is also required
How quickly can my herd gain Johne’s status?
A risk level will be given to the herd from the time of the first herd test. To achieve the highest Johne’s health status (Risk Level 1) three clear, consecutive, annual herd tests are required
I have no idea what level of Johne’s infection there is in my herd so can I test a proportion of my herd to start with?
Unless there is a high level of Johne’s disease in the herd it may be difficult to detect infection just by selecting a random sample. If there is Johne’s infection in the herd it is beneficial to test all of the adult herd to identify the infected animals at an early stage preferably before they show signs of disease. However if you wish you can target test some of the thinner cows in the herd initially as they are more likely to be positive. In order for the herd to be given a Risk Level status all cattle two years old and older will need to be tested.
Once I have gained a risk level for my herd do I need to test every year?
Yes. Once a herd has gained Risk Level 1 status and has had a further two consecutive clear annual herd tests there is the option to move to biennial testing (providing there are more than 20 homebred breeding cattle of two years or older in the herd). This involves testing homebred animals two years old and older every two years. In the intervening year a non-homebred screen must be done, 12 months from the previous test, and any cattle (two years old and older, not including finishers) that are scheduled to be culled must also be tested. If further animals are to be culled before the next herd test is due they must also be tested. Blood and faecal samples should be collected. Blood samples are tested for antibody and if any positive or inconclusive animals are detected the faecal samples can be tested by culture or PCR to confirm status.
When can I move onto testing my herd biennially?
Once your herd has gained Risk Level 1 status and has had two subsequent consecutive clear annual herd tests
Which cattle do I test for the annual herd test?
All cattle two years of age and older
When is the best time to test my herd?
Annual herd testing is usually sufficient for most beef herds whereas heavily infected herds are better to consider testing every six months and cattle down to 18 months old. If possible consider testing a few months before calving to identify any reactors so that they can be moved to a separate pen to reduce the risk of the other calves born into the herd being exposed to infected faeces.
· In dairy herds blood testing at drying off (and possibly again pre-service at around 4-6 weeks after calving) is useful as it identifies reactors so that they can be calved in a separate area from the others and so that their colostrum and milk is not fed to calves. Quarterly milk testing can be done for Johne’s disease however the test is less sensitive than blood testing and there are a slightly higher number of false positives with milk testing compared to blood testing. However milk testing is better than no testing.
Can I test cattle under two years old?
Unless the herd has a relatively high level of infection then blood sampling cattle under two years old will rarely detect infected animals.
Johne’s disease Vaccination
Can I use vaccine to protect my cattle against Johne’s disease?
Vaccination is rarely recommended, except occasionally in very heavily infected herds. It can interfere with TB testing and it will not prevent infection and shedding but it may reduce the number that develop clinical signs. It is better to control the infection through blood sampling of the adult herd to identify infected cattle at an early stage so that they can be segregated from the herd and planned for culling, whilst they are still in good body condition and worth a significant amount for slaughter. By carrying out the annual herd test of the adult cattle a few months before calving it allows the reactors to be removed from the pens where the calves are born and reared which reduces the risk of new infections occurring. The reactors can be calved separately and it will often be possible to rear beef calves on their dams to an age where they can be weaned and the cow then removed for culling.
Johne’s - Added Animals
What testing is required for bought-in animals?
Unless they are animals that have been born and have resided in a RL1 herd since birth (in which case testing is optional) then:
All cattle must be tested using blood for Johne’s antibody and faeces tested by PCR or culture (irrespective of their age)
If negative for all tests they can then be added to herd but must be tested on an annual basis thereafter.
If a group is purchased from a herd and one or more animals test as positive the other animals in the group are classed as Risk Level 5.
What testing is required for animals returning from show/sale?
Providing they have been away for less than seven days at a time then testing for Johne’s disease is not required on their return.