NADIS Veterinary Report and Forecast–October 2006

UK - NADIS is a network of 40 veterinary practices and 6 veterinary colleges monitoring diseases of cattle, sheep and pigs in the UK. NADIS data can highlight potential livestock disease and parasite incidences before they peak, providing a valuable early warning for the month ahead. NADIS disease bulletins are written specifically for farmers, to increase awareness of prevalent conditions and promote disease prevention and control, in order to benefit animal health and welfare. Farmers are advised to discuss their individual farm circumstances with their vet.
calendar icon 16 October 2006
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CATTLE

Adults

Fertility
Fertility reports increased in September as a result of an increase in the number of non-detected heats. Over all the summer infertility reports were significantly above average, indicating what many NADIS vets have suggested that the high temperatures had adverse effects on fertility. Indeed NADIS reports continue to suggest a continued impact of the weather on fertility, for example one NADIS vet reported this month that a lot of the dairy cows in his area had not come through the summer well and were in poor body condition. Particularly when combined with low levels of winter forage this is highly likely to impact on future fertility.

Anoestrus seems to have been the condition most closely linked to the high temperatures with reports significantly above average in June and July and average in August and September.

Figure 1: Comparison of the percentage of summer (i.e June to September) anoestrus reports made in June and July 2006 with previous years. It is likely that the warm start to summer was associated with at least some of the increased reporting.




The number of abortion problems reported in September remained below average (as it has been for most of the year). It is interesting to compare the NADIS data with the VIDA data which is our main source of surveillance data on cattle abortion. Figure 2 shows the change with time in the number of reports per year from both databases. This shows that the number of reports by NADIS vets is much more variable than those of the veterinary laboratories, with a much greater impact of the 2003/2004 brucellosis outbreaks on NADIS reports than on VIDA reports. Figure 2 also shows that the number of NADIS reports as a percentage of VIDA reports has increased markedly since 1997, increasing from around 3% in 1997 and 1998 to 7% in 2003 and 2004, reflecting the continuing increase in the percentage of all cattle work which is undertaken by NADIS veterinarians.

Figure 2: Change with time in the number of reports for abortion on the NADIS and the VIDA databases (VIDA (+) is abortion reports including BS7 tests for brucellosis, these are not included in VIDA data) (2006 NADIS data is an estimate)




Endometritis reports increased sharply in September with total reports being the highest for any month since March August continuing the trend of above average numbers of cases for every month in 2006. The cause remains unclear as yet. We need more data.

Figure 3: Seasonality of reports of endometritis so far this year compared to previous years, showing that every month this year has had more reports than the long-term average.



Metabolic disease
Despite an increase in the number of reports compared to August, overall the number of reports of metabolic disease reported by NADIS veterinarians remained below average. In particular the 50% rise in milk fever cases compared to August still resulted in cases being two thirds of average re was no evidence of any of the normal seasonal increase in milk fever cases. The number of cases seen so far this year is lower than any year except for 2001. Does this indicate a true reduction in incidence or increased treating by farmers?

Hypomagnesaemia cases continued to follow the same pattern as last year with September showing a marked increase in reports from a very low base in August. Last October there was no autumn peak at all so if this pattern continues there will not be one this October as well. However this is by no means certain as the lack of an October rise as seen last year is unusual and an analysis of the NADIS data suggests that there is a strong correlation between September and October hypomagnesaemia data with the number of reports of the latter being around twice those of the former. If this is the case grass staggers is still unlikely to be a major problem this autumn as the predicted number of cases is still only 50% of average

In contrast to the below average reports of both hypomagnesaemia and hypocalcaemia reports of displaced abomasums were well above average, with more cases reported in September than the same month in any previous year (except for September 2004 which had the same number). Total reports for the year are still below the numbers seen in 2004 and 2005 though. One NADIS veterinarian has decided to try rolling followed by 7 days of a hay-only diet as a treatment for the problem. We await the results with interest.

Lameness
As the end of the grazing period gets nearer, more attention to lameness is essential. The two most important diseases at this time of year are white line disease and digital dermatitis. The former usually has a late season peak in September and October and this September was no different with cases increasing 40% compared to August. On farms with a white line problem at this time of year it would be valuable to assess the conditions of tracks, especially those near the parlour, and traffic flow into and out of the parlour. Digital dermatitis reports tend to begin their autumn increase in September (77% increase this year), but don’t peak until mid-winter. So if problems that begin now are tacked aggressively now, future problems may be greatly reduced.

Mastitis
The number of reports of mastitis remained relatively constant over summer, due to the low number of reports of summer mastitis than even 2005. The total number of reports this year was not just lower than any previous summer, but <75% of the numbers seen in 2005 which was the previous low. 2006 thus continued the trend for a much flatter curve for summer mastitis with much less difference in reports per month between July, August and September.

Figure 4: Monthly reports of summer mastitis showing the lack of a marked August peak which has been seen in three of the last five summers.




Calves

The recent new that the number of pigs in the New Forest has been doubled to cope with this year’s acorn crop should emphasise the high risk of acorn poisoning this autumn, particularly if winter rations are limited. Other plant toxicities may also be common especially bracken poisoning.

The figures for lungworm in September were very low (<50% of the long term average), indeed they are the lowest number of reports for any September. This is almost certainly a beneficial side effect of the dry summer. However cattle are still at risk of disease if we get wet conditions (particularly if there’s heavy rain) so a focus on lungworm prevention is still essential.]

Levels of both enzootic pneumonia and calf scours increased in September, with both expected to increase in October as the autumn housing period gets properly underway. Calf scour outbreaks have been below average since July 2005. Is this just better management or reluctance to call out the vet to treat calf problems? The calf pneumonia data suggest that it’s at least partly the former as the number of pneumonia outbreaks reported has been around average for the same period. Comments are welcomed.

Copyright © NADIS 2006

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