Timing, they say, is everything, so the management of the Goat Veterinary Society readjusted the programme for the November meeting once the death of a goat from TB was reported.
The chairman, Dr Tony Andrews, indicated that the society had been hoping to have a meeting that avoided infectious disease, but it was not to be this meeting – and with so much action in this area it is difficult to consider that goat keepers and veterinary surgeons would wish to avoid disease topics. The epidemiology of bluetongue was addressed by Anthony Wilson from Pirbright and it was his description of the travelling midge that attracted particular attention.
Most are aware that the midge is wind-borne but the reflection of UV light from water encourages the midge to keep in the wind stream; when the reflection ceases it folds its wings and drops towards the ground.
In this way the midge travels long distances over water but only short distances over land. Considerable energy is required to keep the wings active and dropping down may also be due to a fall in energy or desiccation.
C.obsoletus favours muck heaps and C.pulicaris leaf litter in forests and as the midge is cold blooded it dies off below 15 degrees C. BTV 1 is considered a high risk for the UK and is well established in Brittany; BTV 6 in Holland represents an unknown risk at this time.
In Switzerland, goats for export to Sweden have been identified with BTV 25, but this may not be a true bluetongue virus: it is known as Toggenburg virus, no clinical signs have been recorded and it is considered a low risk to animal health.
Transfer of bluetongue virus is via the transplacental and contact routes and carnivores have been known to become infected by eating BTV positive carcases. An infected goat would give birth to infected offspring, with the virus established within the white blood cells. Infected adults could have been in contact with the placenta of the new born.
The lower immune response to vaccination by goats, compared to cattle and sheep, is guiding Alasdair King of Intervet/Schering-Plough to advise a six-monthly booster following the initial two doses. In general, an annual booster is recommended but the presence of antibody does not indicate protection against BTV.
The goat keepers in the room were clearly anxious to get it right and the situation in France, where 20,000 holdings now have BTV, was a concern. The vaccine uptake has been poor in France in 2008.
Comparisons were drawn between the 13 million farm animals vaccinated for bluetongue in the UK and the vaccination for disease in dogs and cats. The best estimate is a penetration of 35% of 5 million dogs and 7 million cats. The voluntary farm animal vaccination programme for bluetongue in 2008 is considered “a tremendous success”.
There has been extensive follow-up of any adverse reactions and many of the scare stories have been unfounded, in particular the effects on fertility. Veterinary surgeons are asked to please continue to report any concerns and to advise clients to boost in 2009 and maintain a high level of protection. For goat keepers who vaccinated when the vaccine first became available, the booster vaccination is now due.
Rose Jackson of the Scarsdale Veterinary Group introduced the goat club within the practice that encourages better nutrition for the pet goat. Biscuits are not on the list for the preferred diet.
Pet goats are curious and will nibble unusual plants and escapees into the garden can present with symptoms of poisoning. The list of plants to be aware of is quite comprehensive.
There was an interesting discussion about ivy – kill or cure? In small amounts ivy can be an appetite stimulant for goats that refuse to eat. The advice for suspected poisoning is to give strong tea by mouth, keep the goat moving and wait for the vet. The tannins in tea are contraindicated if acorn poisoning is a possibility.
Utilising slides from her own holding, Hilary Matthews described how she managed her goats as “little cows” as she feels that the goat is closer to the cow than the sheep. Specifically addressing the rearing of kids in a small herd, the strong emphasis was on attention to detail.
Clarity of effort
Tremendous clarity of effort goes into the pre-kidding stage: testing, vaccination, worming and physical preparation of the kidding pen. The timing of kidding, using prostaglandins, is managed so that she can be in attendance.
At birth the straw beneath the kids is replenished, a stomach tube is available if the kid is unable to feed and the afterbirth is removed before it is able to be eaten to avoid choking. After 30 minutes the navel is sprayed.
Colostrum intake (140ml) is checked and kids are removed at four days before disbudding, with 12 week weaning. Milk is always fed at the same temperature and best quality skim is preferred to whey. After each feed the equipment is washed and Hilary simply says that it pays “to never cut corners”.
Automation is becoming increasingly sophisticated for goat milking with improvements in cluster design and the identification of goats performing outside set criteria. Wireless transmission to a single point receiver, from the wrist of the milker, with transponder recognition from the goat’s leg, was described by John Baines of Fullwood. Health alerts from conductivity deviation, milk temperature and yield depression are part of the modern system.
The question raised by Mike Dawson of the VLA Worcester, “Is goat milk infected with TSE?”, attracted considerable attention. From routine surveillance of fallen stock, four animals were found with more cases when the herds were followed up.
Two herds have been culled because the level of scrapie started to rise and two herds are under restriction with a low level of disease. Historically, only one case of scrapie (in 2002) in goats has been confirmed from clinical suspects. In the years 2002 to 2008, two cases of scrapie were identified from abattoir surveillance of 5,600 goats.
Milk from naturally infected ewes has been bottle-fed to sheep from scrapie-free stock and a high proportion acquired infection which was transmitted to other lambs. No equivalent information is available for goats.
In France, milk from infected herds and flocks is considered not fit for human consumption. And so the initial question hangs. There is no transgenic mouse with the goat gene and to further clarify the situation a goat milk feeding experiment is needed.
Epidemiology of TB
In the meantime the EU Commission takes the view that milk from sheep and goats from flocks and herds with classical scrapie or sub-clinical scrapie could be a risk to other animals.
The epidemiology of tuberculosis was explained by Richard Clifton- Hadley from Weybridge and he looked at the history as a means of putting the situation today in focus. In 1935 there were over 20,000 clinical cases in cattle; the current figure is over 26,000 reactors slaughtered annually and rising.
The length of each herd breakdown has risen to 286 days and the same foci are present but they have expanded and intensified. The bigger the herd, the longer the period of restriction and the skin test is operating at the limit of performance.
In 2007 cases of TB were also confirmed in cats, dogs, llamas, alpacas, pigs and sheep. In humans 8,500 new cases of M. tuberculosis were recorded, including cases due to the reactivation of latent infection in people over 50 years old. There are 20 to 40 cases of M. bovis in humans each year.
It is relevant that there is an increase in immuno-suppressed people. No multiple drug resistance has been recorded for M. bovis, unlike M. tuberculosis. Cattle are considered to be at high risk where a breakdown with bTB is linked to wildlife and low risk if there is not a wildlife link.
Roger Daniel of the VLA Carmarthen presented the details of the death of a goat from TB and the post mortem findings. Full details are to be published but the extensive changes were visually presented from a female goat that died in June 2008 with multiple abscesses in the lungs and lymph nodes. Spread of infection occurred within the herd from infected sputum, by aerosol, over 15 months.
The herd was located within a TB positive area for cattle, but no nose-tonose contact with cattle took place. Human health is a concern with clinical cases as there is close contact with goat owners, a risk from unpasteurised milk and possible inhalation of infected aerosol.
Veterinary surgeons attending goats are urged to consider tuberculosis when alerted about goats with respiratory disease. Post mortem of early deaths in the source herd could have prevented expansion of the incident.
Good co-operation was received from the owners of the 10 herds who purchased animals from dispersal of the source herd. This allowed extensive tracing and Simon Rolfe of the Welsh Assembly described the sequence of events.
Six destination herds were in Wales, three in south-west England and one in the Midlands. There is now considerable concern to assess how widespread M. bovis may be in the goat population. Further information is available from email@example.com.
Following the presentations there was a lively discussion about TB in general and the likelihood of badger involvement with goat TB as well as cattle. The Food Standards Agency will be considering the human health implications and whether restrictions are to follow on the use of unpasteurised goats’ milk.