IMPORTANT   TO ALL MEMBERS

TUBERCULOSIS IN GOATS IN THE UK

TB in goats as at  September  19th 2008

Q. There is an outbreak in Tuberculosis, TB, in goats in the UK. What is the extent of it?.

The outbreak began when lesions of TB were found in a goat in Carmarthenshire. The herd concerned was in the process of being dispersed, and animals had been sold on into several other herds. All  these herds have now been traced and have, or are being tested.  To date unofficial statistics suggest that, in over 20 different herds, 50 animals have been reactors, most of which have subsequently been found to have TB on post mortem or on culture, with some culture results still pending.  

Official figures show 29 reactors, nearly all post mortem or culture positive. The discrepancy arises because animals not  showing lesions have pieces of tissue cultured for up to 8 weeks, and only when culture results are known are the relevant statistics fed into the system, and as that is basically updated by monthly returns, official figures will be below those known on the grapevine.

Q.What is the origin of this outbreak?

It was discovered as a result of a post mortem on a goat in Carmarthenshire.  Typing of the bacterium has shown that it is the strain of Mycobacterium Bovis which is found in both cattle and wildlife in the area where the goats had been kept.  

Q. How is the disease spread?

In goats, the disease would normally spread through head to head contact, which would include sharing hayracks and water bowls as well as general aerosol spread from breath. TB can infect the udder, in which case the milk is infective until or unless it is pasteurised.  Sputum coughed up can be swallowed and thus infect dung. 

Q. What are the symptoms?.

Most commonly in goats, it is seen as a chronic cough which is unresponsive to treatment. That may be accompanied by a gradual loss of weight, and sometimes diarrhoea.  A difficulty is that the animals affected often show no sign whatever of the disease at least until it has progressed  to a considerable extent.

Q. How long after  a goat has become infected before it can infect other animals?

We are not currently aware of specific research into this in goats. However in cattle,  infection can be passed from one animal to another after only a few days post infection,  long before any possible signs appear, and usually well before enough immunity has developed to trigger a result to skin or blood testing. It is  reasonable to assume that the same happens in goats.

Q. How do we test for it?

The initial test is a skin test which compares the reaction to injection of two strains of tuberculin.  This test detects antibody to the disease. This test  is spread over 3 days, with the TB extract, Tuberculin, being injected on day 1, and the reaction read 72 hours later.  This is the standard test used in cattle.

NOTE TO VETERINARY SURGEONS  It is advisable to inject  the Avian and bovine tuberculin on opposite sides of the neck to obtain the required separation between the injections.

Q. Is this test 100% accurate?

The test is never 100% accurate because the animal produces antibody to TB in a cyclical pattern, which means that, in cattle at least, there is  no detectable antibody in  about 12%  of infected animals at any one time.  Thus there will always be cases that go undetected on a first test, and  a test on an individual animal, while being a good guide, can never be taken as proof that the animal is free from TB.

There is also a blood test, known as the gamma interferon test, which has not been evaluated in goats.  It may be used in conjunction with skin testing in the current outbreak if the situation requires it.

Q. Why have goats not been routinely tested for 30 years?

Simply because no reactors had been found for over 20 years  when routine testing of them ceased in around 1978.

Q. Some animals, both goats and cattle, which react to the test, subsequently show no signs at post mortem.  Why is this?

Antibody production probably starts some 2 to 4 weeks after the animal has been infected.  Lesions that are visible on post mortem will not be present until at least six weeks after the initial infection, and it can be a lot longer.  Thus the animal will react in advance of the disease progressing to a stage when it can be seen. TB always localises first in the retropharyngeal lymph nodes, and sometimes the organism will grow in culture from these in reactors, before lesions are visible.  These are confirmed positive.

Occasionally the antibody will overcome the disease. If so, antibody will remain in the system for some while, and these animals will therefore be reactors. Unfortunately there is no way of knowing which these animals might be, and they are indistiguishable from those just about to become culture positive.

Q.  Can any goat legally be tested for TB?

In effect yes.  Traced animals will be tested on the instructions of DEFRA, currently at their expense.  

Under certain circumstances it may be wise to have your goats tested voluntarily.  That will be charged for privately by your vet, who needs to be an LVI authorised to  carry out  TB testing.  Before undertaking a private test, the protocol is that the LVI must seek permission from the Divisional Veterinary Manager, and must send the DVM a copy of the test chart.

Q.  What circumstances might those be?. 

  If you are in an area of know high infection amongst cattle

If you are buying in new goats, including bucks, which might be at risk.

If you drink the milk from your own goats.

If you believe you have bought goats from a herd with known infection. Although that should show up on tracing, it does not always happen, and the fact that you have heard nothing from DEFRA should not be  taken as a guarantee that your goats are not at risk. 

Although there is no evidence at present of TB having spread at shows,  show committees need to play safe, and goats that are to be shown may need to be tested first.

IF YOU ARE SELLING UNPASTEURISED MILK  it is a legal duty under the Dairy Hygeine regulations to have your animals tested, privately and at your expense, on a regular basis. On the principle that  no reactors had been found in goats for about 50 years, that aspect of the regulation has not been enforced up to now, but this is a new situation, and it is likely that it will be.  There is as yet no recommended testing interval laid down, but in the present circumstance, it would be wise for all concerned to book a test as soon as possible. The Food Standards Agency are currently carrying ot a ridk assessment.

In the meantime, if you are selling  raw milk through local outlets, TB testing your goats is the only way to demonstrate “Due diligence”.

If you are drinking unpasteurised  milk from your own goats, there is no legal need to have your goat TB tested, but given that we do not know how far this outbreak is likely to have  spread, it would be a wise precaution, in particular if you are in an area where there is known to be TB in wildlife or badgers, or if you obtained your goat from such an area.

Q. What about goats milk bought from shops?

Most goats milk, and milk products such as yoghurt and cheese,  sold in shops is pasteurised. Pateurisation kills TB bacteria, and makes the milk safe to drink under all circumstances.  There are a small number of outlets selling “Raw”, usually locally produced goats milk and milk products. These outlets are likely from now onwards to need to prove that their sources are TT attested goat herds, but that is currently only at the discussion phase.

Q. What about the meat?

  All animals slaughtered for meat are subjected to a rigorous inspection, which includes an examination of the retropharyngeal lymph nodes for TB.

Q. Can the disease be treated in goats?.

In theory, a long course of antibiotics might cure the disease, but it would be impossible to tell whether an infected animal had been cured or not, and therefore slaughter of the animal is the onlly realistic option.

Q What  can I do to prevent it?

If you are in  an area where there is known to be TB, keeping your goats in a  building which no wildlife can enter is the first priority, though that is easier said than done.

In particular, make the foodstores as wildlife proof as possible!.  Grazing goats in infected areas is always an inevitable risk, but one which can be reduced by fencing off known badger latrines.

If you are buying goats, in particular from a known TB area, have them tested privately before they move. That is not a guarantee of freedom from disease for reasons explained above, so best practice of all would be to isolate the bought in animals and test them again about 2 months later. This will minimise any risk as much as is reasonably possible, but is not quite 100% proof of freedom from TB.

Q. Apart from through milk, is there a possibility that humans could catch it?

YES, with inhaling infected breath being the most obvious manner. Remember that feed and water bowls and even dung can be contaminated with TB, which can live for several weeks outsde the body. It is therefore  good practice always to wash your hands after handling goats, and indeed any other animal, and also not to eat, or smoke cigarrettes in the meantime.

Q. What happens if I have a reactor in my herd?

Best practice is that it  will be slaughtered and post mortemed.  Under  present policy, the protocol that is to  be followed will mirror that taken in cattle, and will thus depend on what is found upon post mortem and culture.

Q. What will future control policy be?

A discussion group of interested parties hs been established. That includes Animal Health veterinary surgeons,  epidemiologists, A veterinary Surgeon from the Welsh Assembly Government,  and two representatives from the Goat Veterinary Society.

Initial policy was  aimed at finding out just how widespread the problem is, a process which is now well under way.  Occasional reactors are still being found, but all that are known of seem to have been connected to the original group of farms and those  farms who had purchased livestock from them. It is also Aimed at testing any possibly vulnerable animals as quickly as possible, whether in an official or private basis to minimise further spread of disease, and at safeguarding the health of anyone consuming milk or milk products from goats milk which has not been pasterurised.

Subsequent policy will depend on just what  has been found and where once tracings are complete, and it is proposed to rconvene the group at that time to look at the situation in the light of what has come to lght in the meantime.

Q. Is TB in goats notifiable?  YES. The DVM must be informed.

 Q. IS THIS THE ONLY RECENT OUTBREAK IN GOATS?

NO, but it is much the most serious one.  There have been two other goats found this year with TB.  Both were closely associated with cattle TB, and there was no spread from these as they were one off incidents in single goat herds.

In 2007 there was an outbreak in South Wales, mainly affecting LLamas, but one angora goat on the same premises was a reactor with lesions.

Q. What is the legal position of goat herds with TB?

There is no LEGAL framework for enforcing the testing of goats, or indeed the slaughtering of reactors, and no compensation is payable for slaughtered reactors. The relevant TB orders apply only to cattle. If you are selling raw milk, then there is a legal obligation  to test your goats under Dairy Hygiene regulations.

In the meantime there an onus on goatkeepers to help themselves and each other  to eradicate  the disease from goats.  

The Goat Veterinary Society and The British Goat Society are pleased to hear that to date goatkeepers have been very helpful  and responsible in achieving that end. However it would only take one person to refuse to take proper advice, and to sell or even show infected goats, to negate all the good work being done. The representations that we have been making have been made  in discussion with, and with the full support of, The British Veterinary Association, of  which the Goat Veterinary Society is a division.   

Back to top