Newsletter Johnes Disease Special Edition 2003

JOHNES MONITORING SCHEME - THE LAUNCH
We launched our new Johnes monitoring scheme on Monday 10 February 2003.

We apologise that this coincided with an OADS meeting, but when we arranged our launch we knew we were receiving a visit from Ross Finnic the same day and hoped that he would be able to attend. Unfortunately he was not able to be present, but nevertheless we were delighted at the turnout to the presentation made by lain McCulloch and Dr Sandy dark.

WHY JOHNES DISEASE?
We tackled BVD first because it damages the immune system of animals that have been in contact with it, making them more susceptible to other diseases - including Johnes and TB.

After BVD, Johnes is the next biggest disease problem in Orkney's cattle herds - and it is on the increase. We have received numerous requests from members wanting us to do something about it.

WHAT IS IT?
It is a progressive wasting disease caused by a bacterial infection. Animals lose condition rapidly and start to scour. There is no treatment or cure. It usually affects animals in their prime (i.e. cows aged 5, 6, 7), but it can also affect younger animals and breeding bulls.

WHY MONITOR RATHER THAN ERADICATE?
Hopefully monitoring herds should lead to eradication in others.

Testing for this disease is not as easy as it is for BVD.

The two tests used are blood testing or dung sampling, but neither of these can detect infected animals until shortly before they start to show clinical signs. For eradication, a whole herd test would have to be performed at least once every year, although an increased level of accuracy would be given by testing the whole herd every six months. This is not cost effective for most herds.

A more practical method for infected herds is to avoid keeping homebred replacement heifers -especially if their mother was diagnosed with the disease. This dictates that replacements must be bought-in, and here is where the purpose of our monitoring scheme becomes apparent.

Herds that are infected with Johnes need to source replacements from herds that are not.

HOW DOES IT WORK?
Buying replacement animals from monitored herds will significantly increase the confidence of the purchaser

This is how it works:-

1. All your cull and fallen cattle are tested. This is performed by your vet, who will confirm the identity of the cow as the source of the sample.
2. Samples should be collected in the period prior to the culling date. As much notice as possible should be given.
3. Inconclusive results will be clarified by microbacterial culture of the dung sample. Positive results, in disputed cases, can be subject to the same scrutiny.
4. Your vet will confirm that the cows from which the samples were taken did not demonstrate symptoms consistent with Johne's Disease. If such symptoms are present, then steps must be taken to eliminate Johnes disease as the cause.
5. Farmers should provide a dung sample from any adult cattle in the herd suffering from a significant bout of diarrhoea, with or without weight loss. Many cases of the disease begin with repeated bouts of diarrhoea interspersed with prolonged periods of remission. The animals, however, are still infective in the remission periods.
6. The farmer's vet must confirm that, as far as can be determined, there has been no evidence of Johnes disease on the farm in the past 5 years.
7. The farmer will declare that, to his knowledge, the herd has been free from Johnes disease for at least 5 years.
8. Herds that are currently free from Johnes disease are strongly advised to maintain a closed herd status. If animals must be bought-in, they should be tested for Johnes disease on both blood and dung, and sourced only from herds which can produce veterinary certification that Johnes disease has not, as far as can be determined, been present on the farm in the previous 5 years.
9. Herds will be credited with certification based on the above criteria and stating the number of years for which they have been met. The confidence that can be placed in this certification will grow with the years providing no cases are detected.

HOW MUCH WILL IT COST?
The lab fee for testing a dung sample from a cull animal for Johnes disease is £5 to OLA members. The usual cost is £9 per sample. Your vet will charge £2.50 per sample taken. Blood samples can also be tested for a similar fee.

The total cost of a dung sample will be £7.50 per sample, plus postage. This does not include the veterinary visit fee, but we will assume that you would get your cull cows sampled while the vet was on your farm for other work.

The dung samples may also be tested for other problems such as Fluke, but this would be an additional fee.

I WANT TO GET INVOLVED - WHAT DO I DO NEXT?
If you know which animals will be going to the cull over the next few months, get your vet to take dung samples from them.

If you know that you have not had a case of Johnes on your farm in the last five years, you can get this verified by your vet as well.

You do not need to book your cull cow samples with OLA, as Karen will get a note of them from your vet.

JOHNES PREVENTION

The last thing you want to do is purchase an animal that may be infected with Johnes.

Dr Sandy dark (SAC Thurso) advises that breeding bulls should be dung and blood sampled before you use them. This can be done at the same time as a BVD test (if the bull has not already been tested).

As the usual dung test will only detect the disease in its final stages, he suggested that microbacterial culture of the sample could also be done to give a more accurate result. This method is more expensive (around £30) and takes over 4 months.

You can also collect samples at any time from any animal you suspect may have the disease, which is explained in point 5 of the list of instructions opposite.

Sample pots are available from your vet or the OLA office. When you have taken a sample, you should hand it in to your vet, so that they can take note of the sample before sending it to the lab.