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NADIS Veterinary Report and Forecast March 2009

06 April 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

February was a quiet month on the veterinary front with the combination of a short month and snowfall in the first half resulting in drops in activity across the range of conditions and diseases. Obviously, there may also have been some impact of the credit crunch and recession on veterinary activity, particularly as they led to falls in commodity prices, but we need a few more months of data to accurately track their impact. The restoration of EU export subsidies for dairy products has not as yet put an obvious floor in the UK price for dairy products so it is no wonder that optimism is still in short supply

Adult Cattle

Metabolic disease

The number of cases of displaced abomasums (DAs) was lower in February than January, but still remained at very high levels exceeded only by the peak year of 2005. We seem to have stabilised at a much higher level of DA reports, following a rise in cases which started in 2000. This is clear from a comparison of the number of reports of DA to the relatively stable baseline of reports of non-detected oestrus show. Between 1997 and 2000 DA cases were around 2 per cent of the figure for missed heats, increasing to around 5 per cent for 2004 to 2008 (Figure 1).

Figure 1: Comparison of the proportion of displaced abomasum cases to missed heats from 1997 to 2008

Lameness

Lameness records were more significantly affected by the decline in reports than any other disease or condition. The total number of cases treated by NADIS vets fell from a relatively high 500 in January to <300 in February, well below last year’s figure for the same month. All of the main causes of lameness were reported less often in February, with the most dramatic reduction in cases being that for sole ulcers, which had the fewest reports for any February since NADIS began. This was a major contrast with January, which had over 4 times as many reports as January 2008.

Figure 2: The monthly change in reports of sole ulcer showing the large drop in cases last month

One area of concern that has been highlighted in previous NADIS reports is the change in the number of reports of downer cows. Although the number of cases reported last month was higher than the same period in 2008 (10 vs. 1), the average number of cases reported in February between 1997 and 2006 was 25. Almost the same number of down cow reports was received in January 2004 as in the whole of 2008. This is an area where more information would be extremely useful. Are we getting fewer down cows, consistent with the decrease in milk fever cases, or are farmers not getting veterinary attention for such cows, on the basis that such treatment is not economic? Where have the down cows gone? Figure 3 shows that, despite a slow start, 2008 saw a higher number of down cows than the previous year and so far this year the same trend is occurring

Figure 3: Time series of reports of down cows showing the relative explosion of cases in the early part of this decade followed by a drop after the ending of the OTMS scheme.

Fertility

Last year reports of all the major ovarian problems increased markedly in February with both ovarian cysts and anoestrus reports almost doubling. However, this year all of these conditions had fewer reports in February than January. Nonetheless, the high number of reports in January meant that ovarian disease levels were around the long term average except for anoestrus which was almost 50 per cent below the expected figures with fewer reports than all previous Februarys except for 2007.

There has been much discussion at EU level on the future of cattle breeds, such as the Belgian Blue, where caesarean is the normal route for parturition. Hopefully any forthcoming legislation will prevent scenarios such as that described by Vet 76 (west Glamorgan). One of his clients purchased 6 in-calf Belgian Blue cross heifers. They were in-calf to a supposedly easy-calving Charolais bull. So far 1 has been shot; there have been 2 uterine prolapses, 1 caesarean and the final one was induced early and then given an elective caesarean. The calf delivered measured 36 cm (14 inches) across the hips and was 94 cm (37 inches) from crown to rump!

Figure 4: The monthly change in reports of anoestrus showing the large drop in cases last month

Other diseases

Reports of bovine iritis (silage eye) usually increase greatly in January and then stay at relatively high levels until after April. However this year’s figures are much lower than previous figures and, despite a small rise last month, remain lower than those seen in 2008, which was already very low. As Figure 4 shows the seasonality of iritis hasn’t changed but the peak number of cases has fallen since 2004.

Vet 39 ( North Yorkshire ) described a pneumonia problem in dry cows. Three cows died a month ago and were examined post-mortem, but the VI centre has not been able to diagnose anything with certainty. Blood samples from the dry cows had mildly increased GGT - suspicious of some fluke but the vet thinks that it is more likely to be fatty liver. They found high BVD titres, indicating circulating virus but the herd is vaccinated, as well as fairly high IBR titres, marginal Neospora levels and low leptospirosis antibody levels so it’s all a bit indeterminate. Monitoring is ongoing with a PCR check for BVD on the bulk milk pencilled in for the future.

Figure 5: Change in number of reports of bovine iritis since 2004

Vet 48 (Co. Down) operated on a cow with colic, which on laparotomy was found to have caecal torsion and necrosis. The caecum was removed and the surrounding viable gut untwisted. The cow was up and eating the next day! Gareth reported that this was quite unusual.

Udder oedema is a complex disease, with many outbreaks having an uncertain aetiology. However one demonstrable cause is excess sodium intake. This was clearly demonstrated by a client of Vet 31 ( Lancashire ) who used soda wheat instead of ordinary wheat in his dry cow feed and ended up with three cows with severe udder oedema.

Calves

The numbers of cases of scour and pneumonia tend to fall in February and last month was no exception. Nevertheless both diseases remained above last years figures, in contrast to the decreasing trend over the past four years. So, as yet there is no evidence of the recession affecting veterinary involvement in calf disease.

Vet 72 (Angus) diagnosed the presence of three PI calves in a farm was thought to be free from BVD. The herd mainly breeds its own replacements but their bull had jumped into a neighbours herd for a day in July 2007, around the time when these calves would have been conceived. Ian stated that this could have been the source of infection or it could have been passed nose to nose across the fence. This highlights te problems of keeping BVD free with relatively lax biosecurity.

This time last year we received reports of illegal drugs on farm, and amazingly we received a similar report last month. Again, the main drugs noted were oxytetracycline and tilmicosin, and yet again the purchased drugs were often out-of-date! Action from the authorities seems to have been limited, but this sort of scam is very difficult to police. The only solution seems to be to persuade the farmers involved that purchasing such illegal stock is wrong. Blocking legal internet sales of such drugs would seem to be completely counter-productive as it then means that farmers who want to buy veterinary pharmaceuticals legally over the internet are penalised, without any impact on the illegal sites. It is highly implausible that farmers purchasing products from illegal websites are doing so by mistake. Perhaps this issue should be taken to the farming press.

Further Reading

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


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