New Approach to Tuberculosis

Again it is the Chief Veterinary Officer for Wales Christianne Glossop who is searching for a new approach to controlling bovine TB in her country. You will remember that initially she was pushing for a cull of badgers in Pembrokeshire but after several court battles with the badger trust and a rising swell of public opinion against badger control measures there has been a forced policy change. I think it is realised that the current trend to vaccinate badgers has unproven benefits so realising its limitations the Welsh Chief Veterinary Officer has started to explore other options.

Vaccinating Calves

Ethiopia may seem a long way away but it does have an ongoing Tuberculosis problem in its 53 million cattle and it is free of the restrictions imposed throughout the European Union so there are options to vaccinate cattle there. So far they have started by vaccinating groups of calves with the human BCG vaccine sending them back to the herds that they know to be infected and comparing them to unvaccinated calves when they were slaughtered. It is not stated at what age they were vaccinated or slaughtered but it has been shown that initially the incidence of disease was reduced by between sixty and seventy percent. In this country we have identified that there are different strains of Bovine tuberculosis, some seem to be more active than others and it is not clear if they are challenged by similar or a different type of infection. To me this indicates that there is a lot more work to do if we are ever to get to the stage where there is an effective cattle vaccine against tuberculosis. Indications are that it would be at least ten years before the relevant documentation can be passed by the European Parliament. This will partly depend on the effectiveness of the vaccine and how it will be possible to test vaccinated cattle to monitor them for disease.

Population Control

There is another approach which has not been mentioned. Essentially culling and vaccinating badgers is trying to achieve a reduction in the badger population so they have the opportunity to live a more normal healthier life and not be tempted to search for food in farm yards and amongst your stock. There are drugs we inject that alter the breeding cycle of both male and female dogs to stop them breeding for up to five months. Badgers have a seasonal breeding cycle and the chances are that they would need just one injection each year to disrupt their breeding pattern. Trapping badgers to administer injections to stop them breeding would never stop all pregnancies, but it could have a significant effect on badger numbers if done each winter and might achieve similar results to the cull and on going vaccination programme.

Lambing Survey

Several industry bodies including EBLEX , the NFU and Meat Promotions Wales have got together to conduct an on line survey to gauge the impact of last years bad weather and the prevalence of disease on this year’s lamb crop. The survey can be found at www.surveymonkey.com/s/WWHBNC5 and the link to it will be active from the farm letters page of our web site. If you want to take part and are not keen on using computers we can help you to do it at the surgery. You are encouraged to report your experiences at the end of lambing whether or not you have had problems. There is a danger that only farms that have had significant problems will complete the survey and we will get a distorted view of what is really happening on our farms. A calf crop survey is planned for later in the year.

Look out for Nematodirus

I am sure that you will realise by now that all animals have worms and that most worm eggs hatch out straight away when they are deposited on the pasture in order to infect the next calf, sheep or horse that comes along. This will perpetuate the survival of the parasite. Nematodirus is different. It is only carried by young animals mainly lambs sometimes calves and each egg that is passed stays on the ground until the following year when large numbers hatch and overwhelm the immune system of young grazing animals. When we have a mild winter larvae will start to appear from February onwards and there will be fewer survivors by the time the lambs go out in March and April. This cold spell has held back the development of Nematodirus eggs and there will be a massive hatch when the weather warms up and you turn your lambs out. You can avoid this if you can turn the lambs onto new pasture that wasn’t grazed by young lambs last year. If this is difficult you will need to drench the lambs every three weeks until they have had a chance to build up a resistance to the infection.

Horse Passports

Horses have been issued with passports since 2005, but they vary in their format as there are some seventy five different organisations that have been authorised to issue passports in the UK. The idea is to safeguard the food chain, all drugs administered must be recorded if there is any chance that the animal might one day go for human consumption.  Many drugs can never be used on horses destined for human consumption either because their residues will stay in the animal for a prolonged time, or because the manufacturers do not have food safety details and it is not economic to do the tests to get them. Some horses have come to this country from overseas and all of these would be accompanied by a passport often in a foreign language that can be difficult to understand.

Residue Testing

Since 2009 there has been a requirement for all foals to be micro chipped, but this does not apply to older animals. Unfortunately there is no central data base where details of passports are recorded. Documents get lost sometimes when animals are sold and it is not difficult to have a new passport issued to animals that would not contain details of any drugs that had been given. Most of the concerns come from a drug called phenylbutasone which can cause aplastic anaemia in some people if it is consumed. Scientists have not been able to agree on a safe minimal dose so it is subject to a lifetime ban. Bute is commonly used as an analgesic to treat injuries and help older animals with stiff joints. It is most commonly given in powder form and that is a danger that owners might use it for a short time on an animal with a muscle sprain and not record any details in the animal’s passport.

 It is very unlikely that anybody would be harmed if they were to eat meat from a horse that was once treated with bute and there are, as far as I know, no recorded cases of any one being harmed by the drug in this way. At the moment all horses slaughtered here are tested for the presence of bute and held at the abattoir until the results are available. It seems that no tests are done for the presence of other banned substances.

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