Tony Yewdall from North Devon and his son Jonnie, were filmed in 2004 watching a TB test on their Guernsey cattle. This was the fourth consecutive 60-day test for this herd. The result was the slaughter of many animals, some baby calves just 3 months old. The vet testing said he felt like ‘an executioner’. Jonnie was so distressed he asked for the cameras to stop filming. From being one of the largest Guernsey herds (at around 450 pedigree animals), carefully built up over some 50 years, and mainly home-bred animals, the numbers were diminishing as a result of bTB policy. The 2004 herd breakdown resulted in the loss of some 90 of their animals to TB but worst was yet to come.

In 2008 eighty nine cows were slaughtered; eleven cows were shot on the farm and the rest (thirty were still in calf) were loaded into trucks to be killed at the local abattoir. The herdsman could not bear it and refused to be present. For the farmers, Tony and Jonny Yewdall, a father and son, it was the blackest day of their farming lives.

The mass slaughter followed the use of a highly controversial new blood test, the gamma interferon blood test, which had been introduced in October 2006. 89 of the Guernsey herd failed this blood test. However, when the cattle were subjected, on the same day, to the skin test, only one showed a positive reaction. Tony Yewdall was obviously not happy with this anomaly and requested that DEFRA allow a re-test. Local officials were apparently sympathetic but were overruled by London, which insisted that no further tests could be allowed, so insisted that all 89 newly calved animals had to be destroyed.

Mr Yewdall, who had successfully resisted having his herd culled during the foot and mouth crisis, was devastated. He told the media: "It's a difficult decision, but getting out of farming is certainly an option. We will have to see what happens with TB in the future. The really hard thing is that we question how many of these animals actually have TB, and that won't be answered until tests are carried out once they are dead. It's a dreadful situation for us." He said the family had offered to pay for a retest privately, but DEFRA had refused to grant the necessary authority to do so. "Why would they refuse if they are confident in their results?" he asked.

Many farmers became so alarmed by the apparent unreliability of the blood test that several, including the Yewdalls, decided on court action. Meanwhile the cattle were kept in isolation for six months, with apparently regular monitoring by DEFRA pending the outcome. One would have thought that over this six-month period, if truly infected, many would develop lesions. They didn’t. After 6 months in isolation, when the court case failed and the cattle were slaughtered, just 2 cattle had visible lesions and a further 3 were found to have the very beginnings of small closed granulomas. It is therefore likely that 84 healthy cows were unnecessarily killed, costing taxpayers nearly £100,000 in compensation alone. The compensation was based on table values and did not cover the true value. The farm's losses were estimated at well over £100,000.

The Yewdalls were devastated and watched in horror as their cattle were shot. One newspaper printed a photo, (which was later to receive an award) that clearly revealed the shocking moment a Government official prepared to shoot one of the cows.

Court action by farmers challenging the blood test results

The first case to court was that brought by a Somerset organic farm (see case study on this case also on this website) – Higher Burrow Organic Farming Partnership. Here the original skin test had shown only 14 of 486 cows as positive. When DEFRA insisted on retesting with gamma interferon, the figure rose to 86. Official figures revealed that over 80% of all cattle destroyed after being shown as positive by the blood test proved, at post mortem, to show no signs of bovine TB. Sadly this first case was lost. Surprisingly, on appeal, the Judge, Mr Justice Mitting, declined to discuss the scientific reliability of the two tests. Instead he said DEFRA's decision to slaughter the animals was ‘not only lawful but mandatory’. His judgment was based solely on the law and he ruled that, because the blood test had been approved by the EU, it was therefore lawful for DEFRA to rely on it. So, even though the EU had regarded the gamma interferon blood test as only an ancillary test, not to be relied on for a definitive diagnosis, Tony Yewdall's cattle and tens of thousands more across Britain were doomed. In view of this decision, none of the other farmers considered it worth continuing legal action as, based on Justice Mitting’s ruling, they were not likely to win.

Background to the infamous blood test

Back in 2006 Defra began a pilot study involving the new gamma interferon blood test. Apparently they secretly selected 24 farms in three to four year testing areas, using bloods from other testing regimes, and tested for bovine TB. Apparently in the areas selected they would not have expected to find any evidence of bTB in the cattle. However, they did – around 7% of samples proved positive. As the blood test was not a recognised diagnostic test at that time, they could not confirm their findings with slaughter. The pilot study highlighted problems associated with issues such as the differing results for length of time in transit of the blood samples, possible co-contamination with recent skin tests, and several other known contaminants, including skin granulomas, the presence of antibodies or vaccinates to Johnnes disease (M. avium paratuberculosis) and other diseases. So, despite the fact that no post mortems were carried out to confirm their results, DEFRA presented the results to the Standing Veterinary Committee of the EU for approval as a secondary diagnostic test for bTB and approval was obtained.

As the blood test is an ancillary test, one would assume that it would need to be backed up with a positive skin test. However, this is not the case. If an animal fails the blood test it must be slaughtered. DEFRA says that the blood test was ‘developed in Australia in the 1980's’, but what is ignored is that Australia achieved TB free status before the blood test was licensed, and it must also be recognized that Australia has a hugely different environment from the UK, with many less contaminants to affect test results.

The blood test was sold to an unsuspecting industry as ‘flexible in interpretation’. This has not been the case and no allowances are made for other known contaminants. It was also described as picking up ‘very early cases’. This too is somewhat of an exaggeration. The difference between the latency of the intra-dermal skin test and gamma IFN is about two weeks, with the skin test averaging 42 days and gamma 28 in experimentally infected animals.

The reliability of the blood test is highly suspect. It was originally designed to be just a quick surveillance test, to be confirmed by the skin test. DEFRA apparently even admitted on its website that the blood test is cruder and less ‘specific’ than the skin test, in that it picks up the presence of diseases other than bovine TB, most not harmful to cattle at all.

Information sources:

http://bovinetb.blogspot.com/2008/04/his-masters-voice-gammaifn.html

http://www.whale.to/a/tb_blood_test.html

http://bovinetb.blogspot.com/2008/05/carnage.html

http://bovinetb.blogspot.com/2004/07/when-grown-men-cry-minister-smiles.html

http://www.telegraph.co.uk/comment/columnists/christopherbooker/3558454/TB-blood-test-has-bloody-results.html

http://www.dailymail.co.uk/news/article-566814/Pictured-The-dramatic-moment-prize-cow-slaughtered-controversial-blood-test-showed-signs-TB.html

http://www.thisisdevon.co.uk/news/Bovine-TB-cases-28-8211-surprise/article-491269-detail/article.html

http://news.bbc.co.uk/1/hi/england/devon/3584217.stm