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NADIS Veterinary Report And Forecast

01 October 2009

UK - This is a monthly report from the National Animal Disease Information Service (NADIS), looking at the data collected from their UK farm inspections.

August was relatively warm and wet, the end of a summer which promised much but didn’t really deliver it. Up to the time of writing, the development of an effective vaccine strategy in France seems to have markedly reduced the spread of bluetongue, which, combined with the continuation of high levels of vaccination in most of the UK, has meant that the risk to the UK of a major bluetongue outbreak has definitely receded. The main risk remains the importation of disease via livestock purchased from infected areas, which is still occurring far too commonly .

CATTLE

ADULT CATTLE

Metabolic disease

Around this time in 2007 we were predicting the start of a downward trend in displaced abomasum (DA) cases. However last year there were three per cent more cases of DA than in 2007. So far this year, DA cases have followed a similar pattern to that seen in 2008. Until August reports were up six per cent year-on-year, but unlike the last four years there was no August peak in cases, so reports are now five per cent down on 2007, but two per cent up on 2008. At the risk of being proven wrong again, it looks like we are settling at a new level below the peak years earlier in the decade but still almost double the case rate of the late 1990s.

Figure 1: Number of monthly reports of DA in 2009 and 2008 compared to mean of 1997-2007.

The number of reports of hypomagnesaemia was very low this spring, even though the number of reports at the start in March seemed to suggest that there may be a lot of cases. The autumn seems to have started in a similar way with the August figures being very similar to those seen in March. The NADIS figures show that there is no correlation between reports in spring and autumn, so prediction is not possible. Last year, for example autumn reports were double those in spring, (primarily due to the very low number of spring reports) far higher than previously reported (Figure 2) .

Figure 2: Comparison of spring and autumn reports of hypomagnesaemia.

Mastitis

July is usually the first month when significant numbers of summer mastitis problems are recorded. In the early years of NADIS a poor July, with high numbers of cases, was followed by an August with few reports and vice versa. However, since 2007, this pattern has been significantly altered with a very low number of reports in July being followed by small rises in August. The same pattern has been seen this year, in fact the August 2009 figures are the lowest ever so the pattern has definitely altered. This may suggest that we have finally achieved reasonable control of summer mastitis, either because of better prevention or because of changed environment, such as housing. However it is possible that it’s simply less reporting to vets .

Figure 3: Comparison of summer mastitis reports in July with those in August for the years 1997 to 2009 showing that low numbers of reports in July are closely linked to high numbers in August except for 2007 (yellow box), 2008 (red box) and 2009 (pink box)!.

Fertility

The number of reports of retained fetal membranes decreased significantly in August at a time when there is usually an end-of-summer peak. Over the last twenty years there has definitely been a trend towards later treatment of retained fetal membranes, with the suggestion commonly made that ignoring them until two to three weeks prior to the end of the cow’s voluntary waiting period is probably the most economical treatment regime. However the NADIS figures show that there has been a slow gradual decline in reports of retained fetal membranes, similar to that for many diseases, with no evidence of a major shift .

Figure 4: Trends in yearly reports of retained fetal membranes for 1997 to 2009, showing the decline typical of many conditions

Lameness

Overall lameness reports were below those of last year for the seventh month in a row reflecting the continued decline in the role of the veterinarian in treating lameness. Of the common conditions it is foul-in-the-foot that has decreased the most, with reports so far this year being at 30 per cent of the average for the same period in 1997 – 2001. It is interesting to compare the decline in foul-in-the-foot cases with of retained fetal membranes. As figure 5 shows, the decline in reports of foul-in-the-foot has been greater than for retained fetal membranes, even though treatment of the latter is probably of limited value. Interestingly the data that show that, on average, in the last five years there have, on average, been 4 reports of retained fetal membranes for every one of foul-in-the-foot. Based on published survey data which suggest an incidence of four cases per 100 cows of retained fetal membranes and 7 per cent for foul-in-the-foot, the NADIS data show that a vet is seven times more likely to be called out to treat retained fetal membranes than foul-in-the-foot!

Figure 5: Change since 1997 in the ratio of foul-in-the-foot reports to cases of retained fetal membranes.

Other Diseases

Last year the number of New Forest Eye outbreaks of New Forest Eye almost reached the long-term average. However this year there were fewer cases reported in August than in July and as for summer mastitis, this low number was the lowest number of reports ever in August.

Figure 6: Comparison of number of outbreaks of New Forest Eye recorded so far this year compared with 2008 and the average for 1997 to 2008

CALVES

The summer months are usually months where there are low levels of calf disease, and this has been the case this year. Last year there was a peak of cases of joint ill in August, this year there has been a dramatic drop. Nevertheless there have been more cases of joint or navel ill reported so far this year than in the same period in 2007 or 2008. This was also the case for enzootic pneumonia, with a five per cent increase in cases over 2008 and a 20 per cent increase compared to 2007. The pattern is more complex for calf diarrhoea, where there has been a 11 per cent decrease compared to 2008, but an almost 30 per cent increase on 2007.

Further Reading

More information - You can view the full report by clicking here.


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