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NADIS Veterinary Report and Forecast - August 2008

27 August 2008

UK - Last summer we had over-plentiful rain and the return of FMD. This summer rainfall has again been high, except in Scotland, and we have seen the spread of bluetongue across the country.

Adult Cattle

Metabolic disease

This time last year we were predicting the start of a downward trend in DA cases At the end of the year the predicted fall was smaller than expected because of a high number of cases in October to December. However the total number of cases (680) was still lower than any year since 2002. So far this year the picture is looking very similar to 2007, at least as regards the total number cases; the peak in cases in 2008 was in May, two months later than in 2007. The NADIS data suggest that by year end there will have been between 670 and 700 cases of DA reported very similar to last year’s. Have we reached a plateau or is this a statistical blip?

Figure 1: Number of monthly reports of DA in
2008 and 2007 compared to mean of 1997-2006.

After an almost 100% rise in May, acetonaemia dropped back to low levels in June. Low levels in June are usually followed rise in July. However, such changes vary considerably between years and this year cases have decreased still further in July. Feed is obviously the driving factor, compared to last year the quality and availability is much better.

Last year the number of milk fever reports rose considerably in July, reaching, for the first time that year, the long term average. In 2007 only two months, July and August had reports above the long term average; so far this year no month’s reports have approached the long term average, and the year-end estimate is around 380 reports, which is only 80% of last year and less than 40% of the number of cases reported in 1997. It would be useful to know whether this fall is reflected in calcium sales!

Figure 2: Total yearly reports for milk fever
from 1997 to 2006 with estimated results for 2007

Mastitis

July is usually the first month when significant numbers of summer mastitis problems are recorded. Usually a poor July, with high numbers of cases, is followed by an August with few reports. However this pattern was disrupted last year, with very low reports in both July and August, so it is unclear whether the very low number of reports seen this July will be followed by the expected high number of summer mastitis cases in August or whether last year’s pattern will be followed.

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


Interestingly despite the apparently strong link shown in Figure 3 for summer mastitis, there is no such link for the other major fly-associated summer disease, New Forest eye. The NADIS data also show no link between the July to September figures for New Forest eye and summer mastitis case numbers

Fertility

All of the three most common ovarian problems, non-detected oestrus, ovarian cysts and anoestrus, were reported at levels very similar to those seen in June, against the long-term trend for a small decline in July.

Uterine torsions, abortions, dystocia and caesareans all continued their fall from the very high May figures. The number of uterine torsions remained high in June, with the highest ever number of reports for that month.

The number of reports of retained fetal membranes fell, however endometritis and metritis cases rose slightly. The ratio of RFMs to endometritis cases has fallen markedly over the last ten years. In 1997 there were around 4 cases of endometritis per RFM case; in 2007 the ratio was 8 to 1. However this increase has really only occurred in the last two years. Is it due to increased testing for endometritis or to farmers saving money by not calling out the vet to treat a retained cleansing?

Figure 4: Time series graph showing increase in ration of endometritis to RFMs since 2006

There are rumours around that bluetongue vaccination has been associated with abortion in cattle. However neither of the two companies has found any problems where the link was likely. We would urge anyone with concerns to contact the manufacturer of the product so that such claims can be investigated as quickly as possible.

Lameness

White line disease, sole ulcer and foul-in-the-foot all increased after the fall in June, with foul-in-the-foot cases even reaching the long-term average. Overall lameness reports are just above the levels seen last year; if this continues it will be the first year since 2004 to see an increase in lameness reports

Figure 5: Trends in monthly reports of lameness for 2007
and 2008 compared to the average of 1997 to 2006


There are rumours around that bluetongue vaccination has been associated with abortion in cattle. However neither of the two companies has found any problems where the link was likely. We would urge anyone with concerns to contact the manufacturer of the product so that such claims can be investigated as quickly as possible.

Lameness

White line disease, sole ulcer and foul-in-the-foot all increased after the fall in June, with foul-in-the-foot cases even reaching the long-term average. Overall lameness reports are just above the levels seen last year; if this continues it will be the first year since 2004 to see an increase in lameness reports

A North Yorkshire vet reported that one of his clients has an ongoing problem with perineal nerve paralysis. There is no obvious cause on this farm, so we would like to hear suggestions as to possible causes.

Other Diseases

The number of outbreaks of New Forest Eye reported remained flat in July; so far this year New Forest Eye cases have been behind even last year’s very low levels.

Figure 6: Comparison of number of outbreaks of New Forest Eye recorded
so far this year compared with 2007 and the average for 1997 to 2006


A Powys vet reported an unusual case where 3 cows died over a period of 2 weeks with symptoms of dehydration and collapse. On post-mortem the oesophagus was found to be blocked and a large amount of fodder beet in the rumen. Blockage with beets and similar products is not unusual, but the main sign associated with choke is usually pronounced gassy bloat. In this case the blockage was incomplete allowing the eructation of gas but not food.

An unusual problem was seen in Cambridge in a group of near-calving heifers. They became lame with swelling at the coronary band. These swellings then abscessate and burst and the lameness clears up. The stockowner thinks that bluetongue vaccination is involved. Any suggestions welcomed!

In June a Wiltshire vet reported on what appeared to be a classic case of botulism. This has now been confirmed with one heifer being positive for Botulinum toxin D and the bacterium itself being cultured from the second heifer. The most likely source was chicken litter and the vet commented that he thought cases might increase with more farms disposing such litter to land. This seems to have been a very prescient comment as, in July, an outbreak of botulism in 4 cows near Preston which was confirmed by the laboratory. The affected had been grazing on a field that had been liberally spread with poultry manure. A vaccine from New Zealand will be tried to stop the outbreak as the farmer has 300 tonnes of silage that he needs to feed the cows in the winter which has been contaminated with poultry manure. Interestingly, New Zealand has never had any reported cases of botulism in cattle so cattle vaccination is unheard of there!

An unusual outbreak of ringworm was seen in Shropshire. In the two month gap between two short interval TB tests over 60% of the cattle had developed ringworm, with many cows having multiple lesions. The source is not clear as it’s a closed herd with no contact with neighbouring cows. The severity of the outbreak strongly suggests that the affected cattle have not encountered the disease before.

Calves

Joint ill reports increased in July resulting, for the fourth month running in the figures being around the long term average. By comparison, last year only two months in the whole year were near that average. In contrast there were only two months last year when levels were near the average. Calf pneumonia and scour cases reduced between June and August, as is normal for the season, but are running at levels higher than last year. Indeed more calf scour outbreaks have been reported so far this year than in the whole of 2007. Nevertheless the number of reports for both scour and pneumonia are still below the long-term average

Figure 7: Comparison of number of total number of reports per year
for calf scour and pneumonia showing the very consistent decline in cases (blue dashed line)
for calf scour and a similar decline for pneumonia (with a marked blip for 2001)

A Powys vet reported that one of his clients had 2 calves due to Clostridia despite vaccinating with an 8-in-1 vaccine. The farmer is now going to vaccinate with a 10-in-1 vaccine. Such vaccines are relatively new on the UK market and there is still limited evidence that they are necessary on most farms. However anecdotal evidence suggests that on some farms they may be useful. We would be very interested to hear any comments on the use of 10-in-1 vaccine.

Further Reading

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


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