The term “enterotoxaemia” in goats usually refers to infection with one of a group of bacteria referred to as Clostridia, and these organisms are part of the normal gut flora, aiding in the process of digestion. This is an important factor when developing an understanding of this disease at the outset, you don’t buy it in with a purchased goat, your goat doesn’t pick it up at a show, it doesn’t pick it up from another goat in your herd – most goats will already have a low harmless level of infection in their gut. Your primary aim is to keep that level under control!
Clostridial infection is not just confined to goats; in the UK all ruminant species and also camelids such as alpacas and llamas can develop disease. In sheep for example, there are approximately 8 different clostridial diseases that most shepherds vaccinate against (using the so-called “4, 7 or 8 in one” vaccines, named after the number of clostridial disease that are protected by the vaccine). If you have mixed species on your unit – then ensure (with your veterinary surgeon) that any clostridial disease preventative programme you have, covers all susceptible species.
Luckily for us, goats suffer from very few of the many diseases caused by Clostridia, although they are particularly susceptible to disease caused by C perfringens Type D – “enterotoxaemia.” Tetanus may also be a problem, but the gas-gangrenous conditions such as Blackleg, Malignant Oedema, Black Disease, and Braxy etc are rare.
Clostridium perfringens Type D enterotoxaemia
Clostridium perfringens Type D is the same organism responsible for causing Pulpy Kidney in sheep, although the presentation in goats is quite different. It is important to stress yet again, that this infection is due almost entirely to an imbalance between the immunity of the goat and the level of infection of what is a normal inhabitant, in its gut. Precipitating factors include a sudden change in diet, overfeeding cereals, or the sudden introduction of lush grass or other vegetation. Stressful insults such as transport, pain or fear may also predispose to infection in a susceptible goat.
If the organism is allowed to multiply rapidly in the gut, it produces increasing amounts of a powerful toxin that is absorbed into the blood stream causing toxaemia, with damage to brain, heart and blood vessels, in addition to severe damage to the gut wall itself.
Age group affected – disease can in theory develop at any age, but is less common in young kids.
Clinical signs – there are 2 main presentations:
- Per-acute –goats can simply be found dead without any other apparent signs.
- Acute – the most common presentation in which diarrhoea or in more severe cases dysentery (blood in the faeces) is seen. As the condition develops, a large amount of mucous and shredded gut wall may also be passed. The rapidly increasing toxaemia results in other signs including collapse, shock, and nervous signs including convulsions, affected goats may be very vocal, suggesting severe abdominal pain.
Disease in live animals is fairly characteristic, and is normally confirmed on its clinical appearance and the elimination of other possible causes of dysentery and diarrhoea. Faeces samples sent to a laboratory may be tested for the presence of toxin, and the post mortem features are fairly characteristic.
Treatment – success depends on the stage the disease has reached before treatment begins. Your vet must be contacted as a matter of urgency if you suspect that your goat is affected to ensure a rapid treatment regime is begun. Fluids eitherorally or intravenously are always effective, with pain relief and anti-inflammatory agents. Pulpy Kidney antiserum (containing Clostridium perfringens toxin) may also be useful.
Prevention - there is an effective vaccine available. As already stated, goats suffer from only a small number of the clostridial disease that affect sheep, and your veterinary surgeon will normally advise that you use a “4 in 1” vaccine such as Lambivac. This vaccine used to be licensed for use in goats in the UK, but the company decided (on economic grounds) not to re-license it – and currently NO VACCINE is licensed for goats. There is however overwhelming evidence that this 4 in 1 vaccine is likely to be the most effective tool in controlling enterotoxaemia. One important point to bear in mind however is that goats do not appear to be able to produce such good immunity to clostridial vaccines as sheep, (another reason for using a vaccine with only minimal components thus ensuring that the goat’s immune system is directed to the important clostridia and in particular C perfringens Type D). For goats that have never been vaccinated previously, the manufacturer’s recommendations for sheep must be followed and this will include two initial “priming” doses. Unlike in sheep however – it is important that goats then receive a booster dose every 6 months – ensuring that this dose is given 4-6 weeks pre-kidding in pregnant does, thus ensuring high levels of clostridial antibody in colostrum.
Moral:
All goat keepers should have an awareness of this disease, particularly:
- The preventative measures available.
- The importance of early recognition of clinical cases.
- The importance of early veterinary intervention if enterotoxaemia is suspected.
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| Raw milk is that which is not pasteurised before being consumed, either as milk, or as products such as cheese or yoghurt which are made from it.
Pasteurisation kills over 99.99% of all bacteria. The process involves heating milk to a temperature of 72 degrees centigrade for 15 seconds and then rapidly cooling it again.. It can thus be mimicked by bringing milk to the boil, which will achieve the same result, and makes home consumed milk as safe to drink as that which has been pasteurised, and in particular guarantees freedom from viable TB bacteria.
THE LIKELY RISK SCENARIOS
 A known infected herd where lesions of TB have been found at post mortem.
Risk level. VERY HIGH for contracting TB.
A herd where reactors have been found, but negative for visible lesions on post mortem
Risk level MEDIUM TO HIGH. Although no lesions were found, you may still have culture positive animals, the cultures only being declared negative if nothing grows after 8 weeks. These animals can be infectious and while the milk itself is unlikely to be a danger per se, it could be contaminated during milking from handling the animal. These herds should in any case be retested after 60 days
A herd which has bought in goats from another source known to have TB.
Risk level, HIGH until the goats have been tested and found negative. Best practice is to test PRE purchase, and retest not less than 60 days later to allow early infected animals to become detectable..
A herd, members of which have been to shows, or had other similar contact with goats from infected herds.
Risk level. probably LOW, BUT not minimal, and testing would be advised.
Herds which have had contact with known infected cattle or other species.
Risk level MEDIUM to HIGH. These goats must be tested.
Herds which are in known TB “Hotspot” areas for either badgers or cattle, but with no known direct contact with either.
Risk level, LOW, but still worth testing the goats. That is PROBABLY how the present outbreak started, but to put the risk in perspective, 1 instance in 50 years does not point to an overall high risk.
Herds which have no contact with other possibly infected goats, and which are outside known infected areas.
Risk level MINIMAL. It would be very surprising if such goats were found to carry TB, but it is just not QUITE impossible.
RISK LEVEL OF CONTACT for picking up TB
So far, TB has been picked up in a number of herds. At present, all of these are direct tracings from known sources of infection. The next stage is the “Onward tracing” from those herds, of herds into which they may have sold animals.
The next concern is shows and other similar gatherings. There is at present no known evidence that this outbreak of TB has been spread through contact at shows. However, it is plainly a theoretical risk, and whether that is translated into an actual risk will depend upon how the goats were housed, in particularly whether potentially infected goats were housed so that they could contact others. That is a line of tracing yet to be undertaken, so it is difficult to quantify what the riskmight be.
THE LAW
Under the dairy hygeine regulations, all animals producing raw milk for sale, need to be tested for TB. Some clarification is needed as to how this will be applied in goats, but plainly ALL herds producing raw milk/products, will need to be tested as a matter of course to maintain confidence in the product..
This risk assessment is produced by the Goat Veterinary Society in good faith, but can only be taken as a guide. In the current situation, we recommend that all producers of raw milk for consumption, whether at home or for sale, should have their goats tested. We also must stress that testing is not a guarantee that an individual goat is producing milk that is safe to drink, as the test does not pick out all infected animals due to the cyclical production of the antibodies upon which the accuracy of the test depends.
POLICY
TB in goats has been extremely rare in goats for the last 50 years. DEFRA, in conjunction with the BGS and the GVS is seeking to stamp out this outbreak if at all possible. It has however to be said that the circumstances which are assumed to have led to this outbreak, are unlikely not be repeated, in particular as TB in cattle has become so much more widespread in cattle over the last ten years.
The GVS and the BGS welcome the actions being taken by DEFRA, and support them, and are actively contributing to disease control through membership of an ad hoc group which has been set up to contain the current outbreak.
DEFRA have stressed how helpful goatkeepers have been in assisting them, and indeed, eradication can only be achieved with that help. It would be a concern if any goatkeeper tried to ignore the facts, and thus helped prolong the outbreak to the detriment of others, and in particular, of goat welfare.
Nick Clayton (GVS).
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Following the recent outbreak of TB in goats, the British Goat Society and its members have some important decisions to make to ensure that the disease is controlled during the present outbreak and to prevent the reintroduction of the disease in future years. The Goat Veterinary Society, together with DEFRA and the Welsh Assembly Government veterinary surgeons, have produced a `Question and Answer' document that all goatkeepers should read.
Although not definitely confirmed, present indications are that the bacterium involved in the current outbreak is Mycobacterium bovis , the cause of TB in cattle. How goats became infected has not been determined, but the initial incident was identified in an area in which the level of TB in cattle is high. Other possible routes of entry are via contact with infected wildlife such as badgers or deer. The outbreak was first discovered in west Wales , in an area where M. bovis in cattle is endemic. Testing and tracing of possible infected goats and animals in contact with them have been carried out by veterinary surgeons from the Welsh Assembly Government and DEFRA, following the protocol that is standard for cattle. Hopefully, most of the infected goats have already been detected, but until tracing and testing is completed, the situation remains unclear and even then the possibility will still remain that undetected carrier goats exist in show herds. The present strain of tuberculosis appears to be very aggressive in goats, and although at present, disease appears to have been confined to the Golden Guernsey breed, other breeds are likely to be susceptible. The organism locally (in West Wales ) does not cause more severe disease in cattle – so it may well be that we are faced with a greater susceptibility to disease in goats (rather than a more aggressive organism), and this is of concern. This year
Veterinary surgeons from the Welsh Assembly Government and DEFRA have advised that the safest course of action would be to have goats tested:
Before being shown
Before being moved to a new home
Before being taken to taken for mating, particularly if being boarded
Before accepting goats for mating or boarding
Show secretaries should carry out a risk assessment to determine the risk at their own shows. The degree of risk will depend on the possible contact of exhibitors' herds with animals known to have TB and/or the attendance at shows last year or this year where infected goats may have been present, e.g. the Breed Shows.
Some shows in high risk areas have already been cancelled; other shows, such as the Royal Welsh, have asked for exhibitors' goats to be tested before attending the show.
Sensible penning at shows will also reduce the risk of disease transmission. Wherever possible back-to-back penning of different herds should be avoided, so that there is no direct nose-to nose contact and stealing of other herds' fodder and green food.
Any goat with respiratory disease, with or without wasting, should be examined by a veterinary surgeon and tested for TB if the clinical signs are at all suspicious. Any goat that dies or is culled because of respiratory signs/wasting should be sent for a post mortem examination at a Veterinary Investigation Centre.
Any bought-in goat(s) should be quarantined for at least 6 weeks and then preferably retested before mixing with the herd.
Next year
Any decision on what to do next year is wholly dependent on what happens over the next few months – hopefully, measures currently being taken will eradicate infection. There is however a high level of TB infection in cattle in certain parts of England and Wales, with concomitant infection of wildlife, which means that there is an ongoing risk of TB being reintroduced into goats, particularly where goats are grazing outdoors in areas of endemic infection.
Veterinary authorities from England , Wales and Scotland have been clear that it is up to goatkeepers to agree on testing and control procedures necessary to prevent the reintroduction and spread of TB within the national herd. The focus of official testing will be on herds selling unpasteurised milk or milk products. Testing of other herds will be at the expense of the owner.
Goatkeepers and the BGS need to decide on what, if any, TB testing should be routinely carried out. This could depend on what part of the country animals are from and how they are kept. For instance, premovement testing is compulsory for cattle from areas where TB is endemic, as is testing if animals are being moved directly from one show to another. On the other hand, goats that are not grazed outside in the eastern parts of England are unlikely to become infected.
The BGS could ask for all goats to be tested annually before the start of the show season, with TB testing carried out at the same time as routine CAE testing, with an additional visit from the veterinary surgeon 3 days later to `read' the test. Although skin testing appears to be accurately identifying animals with infection, the nature of the disease means that not every infected animal will be picked up at any one test, so a single test minimises risk, but does not eliminate it.
In addition shows could ask for animals to be tested just before individual shows and it would be sensible for goats to be tested before moving to a new home.
Any testing regime is going to be an additional financial burden on goatkeepers at a time of rising fuel and feed costs and the requirement to vaccinate against bluetongue, but the risk from TB is unlikely to be reduced in the near future and testing is likely to be a necessary burden if the problems of 2008 are not going to be repeated in future years. The discussion on future policy needs to take place soon, so that consensus can be reached before the start of 2009.
John Matthews, David Harwood (Honorary Veterinary Surgeons, British Goat Society) |
