Restrictions Lifted

There has been good news about the Yorkshire Bird Flu outbreak which started at a duck farm on November 16^th last year. Extensive testing has failed to detect the same strain of Bird Flu in any other flocks so all restrictions were lifted on December 21^st. As far as I know things have settled down on the other side of the channel as well and there will be less chance that migrating birds will bring any further infections our way now. Meanwhile Egypt is still having problems with the H5N1 strain of the virus they have just disclosed that ten people died from the infection there last year and it has become a difficult public health issue.

Post Mortem Service Restored

The Plant and Animal Health Agency has just announced that it has found a private company to under take post mortems on farm animals at Aberystwyth in conjunction with the University. It seems strange to me that they could not run the laboratory them selves as they will be using the same facilities that AHVLA closed down in August. This should help to relieve some of the pressures from the Shrewsbury Laboratory now the lambing season is getting under way.

Pre Lambing Concerns

This is a reminder about the common things that cause abortion in ewes and how to deal with them. By far the most prevalent is Enzootic Abortion as it is highly contagious and spreads from ewe to ewe in the lambing pens. The organism grows on the placenta and starves the developing foetus of nutrients to stop it growing. It is present on the placenta and in the vaginal discharges for up to three weeks after lambing and can survive for six weeks in bedding and on the ground. Ewes that are exposed to the infection at this lambing will remain well until they abort their lambs, usually in the last three weeks of pregnancy, next year. Ewes will only abort once with enzootic abortion they should have a successful pregnancy in subsequent years, but they will remain infectious and pass the infection on to others that lamb at the same time. We need the aborted foetus and some placenta to diagnose enzootic abortion. If you get any abortions, until you know the exact cause clear up any cleansings and isolate the individuals concerned preferably in a separate building. If it does turn out to be enzootic abortion you might end up with a group of ewes that will need to be kept away from the rest of the flock for three weeks or more to safeguard your lambs next year.

Using Antibiotics

Because this is a bacterial disease there is a treatment available to limit lambing losses. A single dose of the longer acting Alamycin injection will check the progress of the infection and should buy you enough time to get live lambs. Some of the lambs may be difficult to rear but it is better than doing nothing. Using antibiotics every lambing on all of the pregnant ewes is second best to vaccinating the breeding flock in the summer before they go to the ram. Remember whatever you do ewes that have been exposed to enzootic abortion this year will abort next year so it is vital to limit the spread of disease when the lambing pens are occupied.

Abortions and Cats

The second most prevalent cause of pregnancy loss for ewes is Toxoplasmosis. This does not spread from ewe to ewe. It is a parasite carried by cats, especially if they catch and eat mice. Young cats are the main culprits, when the infection starts cats usually only shed the oocysts for three weeks before they develop immunity. Sheep develop the disease if they eat grass or other feed contaminated with cat faeces. Early in pregnancy the foetus dies and you are presented with a barren ewe. If it happens later you will see the aborted foetus. Sometimes toxoplasma will affect one twin and the other will be born normally. If you look carefully at the cotyledons you may see the little white spots where the organism grows on the placenta.

Campylobacter Abortion

The bacterium Campylobacter is the third most common cause of infectious abortion in the United Kingdom and has increased in relative importance in recent years. Outbreaks of Campylobacter abortion tend to be sporadic in nature, although abortion rates in outbreaks of 20% or more are possible. The correct handling of abortion material and affected sheep is particularly important since infection is easily spread within a flock. The use of antibiotic treatment in the face of a Campylobacter abortion outbreak generally produces no significant benefits although you will like to think that you are doing something. Ewes which become infected with the organism develop a lifelong immunity and will not abort from this cause again. This means that outbreaks very rarely recur in the years following a Campylobacter abortion incident.

Salmonella Abortion

Salmonella bacteria are the fourth most frequent cause of infectious abortion in sheep in the UK. In the past salmonellosis has been known as “paratyphoid”. Incident report numbers of salmonellosis in sheep are comparable with those in pigs, but are much lower than in cattle and poultry. In affected flocks, losses can be catastrophic, with up to 70% of pregnant ewes aborting.

Salmonellosis in sheep can also cause enteritis, metritis and septicaemia all are potentially lethal to both ewes and lambs.

Infection of a naive flock is usually introduced by a symptomatic carrier sheep, which are also important in the maintenance of endemic infection within flocks. Some types of Salmonella Spread through food and water, in others  mammals and bird are involved.

Salmonella Control Measures

Once salmonella is clinically evident, control measures are restricted to antibiotic treatment and hygiene practices. These are aimed at minimising losses and avoiding spread of infection. Prevention of salmonella infections by vaccination is sometimes possible in future years if you have the Salmonella Abortus ovis strain of the infection.

Human infections

All of these diseases have the potential to affect us so young children and especially pregnant women should not get involved with lambing ewes and new born lambs

The Bovine Tuberculosis Situation

Something seemed to have changed on the first of January last year all of a sudden we stopped seeing reactors and started to see a considerable reduction in the number of avian reactions in the cattle that we were testing. There was a slight setback in June when a single reactor with visible lesions turned up on a hill farm that had been visited by this disease in the past. Subsequent tests on that farm have been clear. In December we found another single reactor with lesions on a hill farm which did not seem to be too serious until everything went wrong and we have suffered a serious outbreak on a dairy farm that had been clear of the infection for over a year. It was soon realised that all of these latest reactors had been grazing on just one field that is too steep to cut for silage. What a difference a field makes.

What’s Next

I wouldn’t like to speculate as to what might happen to tuberculosis in 2015. I would never have thought that a year ago we would have just three farms under restrictions in the whole of 2014 this is a un predictable disease which we are still struggling to understand. It looks as if there will be further reductions in the number of farms affected in Wales. The trend is for more badgers to be vaccinated and no doubt the cull in South West England will rumble on. There is a difficult balance to create an environment which is productive for your cows but where badgers fail to thrive.

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