4 March 2009

4 minute read

Europe

Control of bluetongue remains uppermost on many vets’ minds. Clearly the good figures for 2008 were based on good vaccine uptake so we need to keep levels up and in areas such as Wales we need to expand vaccine coverage.

One area of uncertainty is the safety of vaccination in pregnant animals. We received a report in January of abortion after vaccination in a heifer. This has, as should all such cases, been reported to the manufacturer, and a VLA investigation has not found any link. However rumours continue, indeed one NADIS vet mentioned that he had heard that the risk of temperature rise and side effects was lower in one vaccine than the others. While we cannot be certain, the evidence from the large number of animals vaccinated across Europe with the vaccines available in the UK strongly suggests that, if there are effects in pregnant animals, these effects are rare and unusual. So, as with all vaccination programmes we have to accept a low risk of vaccine-related problems in order to provide sufficient immunity to control the disease. It is important to remember when dealing with rumours that it is potential problems that will be rumoured as ‘vaccine doesn’t cause problem when given to thousands of cows and sheep’ is not very newsworthy, although one report from a NADIS vet stated that one of his sheep clients had their best scanning ever after vaccinating against bluetongue.

ADULT CATTLE

Fertility

Both non-detected oestrus (NDO) and anoestrus cases were far higher in January 2009 than in the same month last year. The rise was most marked for missed heats, with the monthly figure being 50% higher than any month in 2009 and the highest January figure since 2004, and the third highest since 1997. Is this weather related, the previous two winters have been mild and wet, with temperatures and rainfall above average everywhere and had very low levels of oestrus problems – the winter of 2008/2009 has been the opposite and oestrus-associated problems have dramatically increased in January.

Figure 1: Reports of non-detected oestrus in September to March showing that rather than the January rise being untypical it is the lack of rise seen in the last two winters which is unusual.

An even more dramatic increase was the increase in reports of endometritis with the highest number of reports ever for this condition, over 100 higher than the previous record set in January 1998. As Figure 2 shows, this high figure is a continuation of a rise in endometritis cases which, barring seasonal variation, has been apparent since the beginning of 2007.

Figure 2: Time series graph of endometritis cases showing the pronounced seasonality of the disease and the rise in cases since 2007.

Metabolic disease

Overall metabolic disease reports were around the long-term average. This was due to higher than expected numbers of DA cases as both milk fever and acetonaemia cases were lower than average. The rise in DA cases without a comparative rise in acetonaemia cases again highlights the fact that these two related conditions do not have identical aetiologies.

Lameness

Cattle lameness was up markedly in January compared to December with white line disease, sole ulcer and digital dermatitis all showing marked increases. As is usual in January, sole ulcer was the most commonly recorded condition with 92 reports compared to 72 for white line disease, however these two conditions together accounted for only a third of all lameness cases.

Figure 4: Total monthly reports of lameness in January and February, showing the pattern of slow decline from 1998 to 2006 and the much more mixed picture of the last three years.

Other diseases

Bovine iritis (silage eye), is a relatively new, and poorly understood disease. The NADIS figures show a marked downward trend in reports of the disease. This is more likely to be due to increased farmer familiarity with the disease reducing the need to call the vet out than a true reduction in the disease due to improvements such as better silage production. We need better data, such as that which can be got from sentinel farms to properly assess the current importance of the disease.

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

CALVES

The poor winter weather was reflected in rises in both joint-ill and pneumonia cases, with the former rising to numbers not seen since 1999. In contrast, despite the rise, cases of pneumonia remained well below the long-term average at around half the numbers seen in the late 90s. As usual there is significant variation across the country; Vet 12 (Cumbria) commented that the cold weather has resulted in a large number of pneumonia outbreaks in his are, with RSV predominating – which he put down to many people stopping vaccinating over the last few years, while Vet 72 (Angus) reported that he had seen a lot less pneumonia in the past 4 weeks than normal.

Figure 6: Comparison of reports of joint and navel ill in January between 1997 and 2009, showing the marked decline between 1999 and 2000, and the relative stability in case numbers until January 2009.

Further Reading

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