NADIS Veterinary Report and Forecast–February 2008

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

3 March 2008

8 minute read

Europe

CATTLE

Fertility

Both non-detected oestrus (NDO) and anoestrus cases showed no evidence of any rise in January. The number of reports of both diseases was even lower than in January 2007, which had been the previous lowest January. Until 2007 January had usually been the peak month for anoestrus and non-detected oestrus, however last year January, February and March all had similar figures. Is this a change in management with farmers happier to leave cows non-pregnant for longer in the middle of winter or just a statistical blip? Have the last two winters just been very good for oestrus problems – they’ve both been mild and wet, with temperatures and rainfall above average everywhere.

Figure 1: Reports of non-detected oestrus as percentage of the total cases from the previous year. This graph shows the variability in this figure but both 2007 and 2008 are lower than previously seen.

Last January reports of ovarian cysts were similar to the long term average despite the low number of reports of NDO and anoestrus. However this year reports of ovarian cysts were around 2/3rds of the long term average and were lower than in December. From 1997 to 2006 January reports were always higher than the previous December, however, in 2007 and 2008 this has not been the case

Overall in 2007 the number of reports of ovarian cysts was higher than in 2006 but lower than in 2005. The number of cases of ovarian cysts reported to NADIS seems to be cyclical with no obvious long term trend, in contrast to anoestrus where the NADIS data suggest that there has been a real decrease in reports since the late 90s.

A Devon vet reported that one of his farmers uses one of the new heat detection systems which uses neck colour and seems to be getting on really well with it. They have several going around in his area and seem to be very economically beneficial.

Figure 2: Reports of ovarian cysts and anoestrus showing that the number of reports of the former appears to be cyclical whereas anoestrus reports seem to have stabilised at a lower level than the late 1990s

Metabolic disease

Overall metabolic disease reports were well below average in January. This was particularly marked in the cases of milk fever which was 50% below the long term average and 33% less than the previous low for any January since 1997, a further continuation of the downward trend in milk fever reports which seems to have begun in 2004. If previous NADIS patterns continue it is likely that there will be few cases of milk fever reported in February and March as these two months tend to be very similar to January.

Figure 2: Monthly reports of milk fever in January and February with January 1997 as the baseline.

As has been consistently reported over the last four years, the most common metabolic problem reported by NADIS vets has been displaced abomasum and January was no different. The total number of reports was lower than 2007 but still higher than any year before 2004. This is more evidence that the number of DA cases has plateauxed at a level about three times that seen in 1997. March to May remain the peak months for DA but the NADIS data suggest that the peak is moving towards March rather than April as in the past.

Figure 3: Reports of displaced abomasum in January and February showing the increase in cases over the past 8 years.

Lameness.

The continual decline in the number of lame cows seen by NADIS vets was again apparent in January. The number of lame cows seen was the lowest ever for a single month, 50% of last year and 33% of the long term average. This pattern was most obvious for white line disease and sole ulcer both of which were less than 25% of the long term average. January is usually the peak month for sole ulcers due to the combination of time since housing and the reluctance of farmers to get the vet out to treat lame cows around Christmas and New Year. January usually accounts for around 10% of lameness cases so if the January numbers are not a statistical blip then we may end up with only slightly more reports of sole ulcer in the whole of 2008 than in the single month of May in 1997

Figure 4: Total monthly reports of lameness in January and February, showing the pattern of slow decline 1998 to 2006 followed by a much steeper fall in the last two years.

For the second year in a row the number of reports of digital dermatitis in January was the lowest ever, consistent with reports from NADIS vets that digital dermatitis is now a problem that farmers live with and do not seek veterinary attention for. The peak months for digital dermatitis are January to March and it is in these months that have shown the greatest decline, whereas the summer figures have not reduced by anywhere near as much. This suggests that the January decline is real and that digital dermatitis is becoming less seasonal. It could be that our control measures are working or that digital dermatitis is becoming an endemic infection with reduced virulence (or both). However it is still a significant problem on many farms costing significant amounts for control and treatment. On some farms NADIS vets have reported that whole herd antibiotics are still needed to maintain the disease at manageable levels. We would be interested to hear your thoughts on how digital dermatitis is presenting on farms 20 years after first being recognised in the UK.

Figure 5: Change in monthly reports of digital dermatitis since 1997 showing the much greater change in January than July

Other diseases

Bovine iritis (silage eye), like digital dermatitis, is a relatively new disease and, again like digital dermatitis, the NADIS figures show a marked downward trend as farmer familiarity means that they are less likely to call the vet and more likely to treat it themselves. This highlights the problem with veterinary surveillance in the UK. Silage eye has been an important problem (and probably still is) but we still have no conclusive evidence as to what causes it and we lack good quality baseline data to track whether silage is being made better or whether problems are being ignored because the farmer knows what it is but doesn’t think it severe enough to call the vet out. The NADIS figures are all we have; VLA and SAC do not record more than a handful of cases per year. Hopefully with the support of funding from levy bodies and Defra we can get baseline data from sentinel farms which will back-up and add greatly to the value of the NADIS data.

Figure 5: Change in monthly reports of bovine iritis (silage eye) since 2004 showing the year-on-year reduction in reports of this disease

Several apparently copper-related problems have been. A Shropshire vet identified a significant deficiency problem on an organic farm. Since undergoing organic conversion this farm has not given any mineral supplements to its stock which has resulted in deficiencies of both selenium and copper. A Lincolnshire vet reported that a herd that is being sold had a severe problem with hypocuprosis with many heifers being stunted and cows showing distinct copper rings around the eyes. He also reported what may be a more unusual copper-related problem in a group of dairy cows that were poor doers with pear shaped abdomens and staring coats, some also had scour.

A group of cattle in Angus became blind with circling and aggression leading to recumbency and salivation with one dying. The illness developed rapidly over 24 hours and the affected cattle even broke down a wall in their panic. A post mortem on the dead cow found normal levels of magnesium with liver vitamin A slightly high and no sign of kidney lead. Body condition was good but the eyes were slightly sunken with a degree of dehydration and some yellowing of the tissues suggesting jaundice. There was extensive subcutaneous haemorrhage especially of the chest and flanks. There was injection of the meningeal blood vessels and a red fibrinous discharge was present over the brain stem at the base of the cerebellum. No other lesions were found. Histology of the brain showed two focal areas of haemorrhage. One was in the grey matter of the cerebral cortex and the other in the mid brain. Possible ammonia toxicity was considered or hypervitaminosis A. We would appreciate any input on this unusual case. Cattle have now settled down following a change of feed.

Another unusual case was reported by in North Yorkshire. A dairy cow that had previously been reported as having had malignant catarrhal fever has made a full recovery. Three other cows that were a bit off colour a few days after also responded quickly to treatment. They were tested for MCF and 1 tested positive. This is a pedigree herd which has had minimal exposure to sheep. Are there any similar reports?

CALVES

All of the main calf problems were at all time lows in January, with reports of pneumonia at less than 40% of last year (30% of the long-term average). If anything the trend downwards in reports seems to be accelerating.

A Dumfriesshire vet commented that in his area the incidence of pneumonia has been especially low this year although the weather has been “ideal” for pneumonia conditions. This might be simply because there are less cattle in his area than there used to be and with more spring calving batches of calves are more even and tend to be vaccinated as groups.

Figure 6: Calf pneumonia figures showing the continued downward trend in reports in January and February