Recumbrant Ewes

Although hypocalcaemia does occasionally occur early in lactation in ewes over three years of age feeding twins or triplets for similar reasons that we see it in newly calved dairy cows that have trouble adapting to the demands of milk production. We see hypocalcaemia more commonly three to four weeks before lambing when the bones of the growing lambs are being mineralised. This draws calcium out of the blood stream of the ewe and sometimes it is only slowly replaced from the minerals in the ewe’s bones. It is most likely to occur if the flock has been stressed by housing or when animals are caught for drenching or other treatments.

Rapid Response

Over a period of two to six hours affected ewes will become isolated from the rest of the flock, their muscles become weak and they will get stranded unable to rise. Some animals will start to get up and may rise up on their knees, but get no further. Ewes with calcium deficiency will often breath rapidly so you may think they are starting to develop pneumonia and could well give them some antibiotics. Uncomplicated cases will respond to 50ml 20% calcium given into the vein or 100ml given under the skin. Calcium works better under the skin if you can warm it first. Also if the ewe has not eaten for more than twelve hours it will be wise to give 120ml of propylene glycol as a drench to stop pregnancy toxaemia developing.

Deformed Lambs

We continue to see the consequences of Schmallenberg infection as more ewes are lambing. The usual presentation is one or more lambs with frozen joints in the front legs. Some animals have stiff necks or deformed heads. Most are born dead, but some may survive outside the ewe for a short time. Lambs with deformed joints must suffer pain and will not be able to suckle on their own so it is not kind to try to rear them. The difficulty is that you will not know what you are dealing with until you have a feel inside the ewe. The tendency is to intervene at an early stage as often one lamb will be normal but could die if a deformed lamb is blocking the birth canal. AHVLA are interested in monitoring the number of cases, but few are being fully investigated as there is little that you can do at the moment to prevent the disease. The hope is that the virus spread unnoticed by active midges in the middle of the summer so there is some chance that ewes lambing in March and April would have developed a natural immunity some time before they became pregnant. The hope is that the vaccine will be licensed before ewes go back to the ram later this year so we will have at least one tool to fight this distressing condition.

Resistant Bacteria

Bacteria have been around for more than three and a half billion years so it is no surprise that they are able to adapt and survive in harsh conditions including the chemicals we expose them to in an effort to destroy them. Bacteria from the soil have been shown to be naturally resistant to many of the drugs we use and often cultures from samples we take are resistant to antibiotics that we know you have never used on your farms. There is always a danger that pathogenic bacteria will somehow pick up these resistant genes and become difficult to treat. This is not a new phenomenon as even Alexandra Fleming warned about the misuse of penicillin when he gave his Nobel Prise Acceptance Lecture in 1945. The debate about resistance has gone on for nearly seventy years now.

Acquiring Resistance

There may seem to be a large number of different antibiotics, but many are closely related to others so there is still a limited number of different ones that we can use to treat bacterial infections. There has been much talk lately of restriction certain drugs particularly the cephalosporins, used to treat mastitis, and the fluoroquinones, used to treat enteritis and pneumonia, for human use only. There is little evidence that resistant bacteria can pass from animals to people through the food chain. Indeed if there were any bacteria on meat when it was brought none would normally survive the cooking process so several things need to go wrong before anybodies health is put at risk. Although some antibiotics are used both in animals and humans most of the resistance problems in people have arisen from human use of the drugs.

Threat of Restrictions

Even if resistant bacteria from animals were able to colonise the human gut it is far from clear if they are able to pass on any resistant genes to have any clinical consequences. There is far more chance that resistance can occur by contact with bacteria that are naturally resistant from the soil. I have no argument against the responsible use of antibiotics but it would be wrong to with draw useful drugs that work on animals because of unsubstantiated resistance problems that doctors have to deal with.

Respiratory Infections

New laboratory techniques are developed all of the time and things that were available to only research scientists just a few years ago are now in common use. There is a technique called Polymerase Chain Reaction that can identify minute traces of DNA in cells. Samples were taken from the tonsils of eighty previously healthy calves at slaughter in Britain. This new PCR technique was able to identify 53 calves with Pasturella multicida and 10 calves with Pasturella haemolytica at the time of slaughter. These bacteria are ready and waiting in the majority of animal to cause disease when the calves are transported or put into an environment where the housing or ventilation is poor. Previous culture methods were only able to detect 20% of the bacteria that were actually present and gave a false impression of the potential disease risk.

Veterinary Laboratory Consultation.

Many thanks to those of you who have looked at the government consultation about closing the majority of the Veterinary Laboratories Agency sites so that they can provide a better service. See last month’s newsletter on our web site.

The internet response form is clearly complicated as the wording leads respondents towards agreeing to the proposals and it is by no means clear what you are responding to in each section. Admittedly we are one of the few favoured counties as the laboratory in Shrewsbury will be one of the four remaining that will stay open. There are still another two weeks to respond to the proposals and I would urge you to took at the web site if you can.

TB Statistics

The latest statistics for the incidence of Bovine Tuberculosis in Great Britain is that there were 4,188 herds affected last year January to October compared to 3,983 in 2011. This resulted in the slaughter of 31,146 animals either as reactors or dangerous contacts. Last year 60,218 tests were carried out on herds that are officially free of the disease. We have a long way to go still.

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