Another month has passed and quite an interesting month it has been, with several topics of interest to keep our intrepid Vet News Editors on their journalistic toes. Rather than lump all of the Vet News goodness in one post, it was thought that it might be best to give each article some more room to breathe, as it were. As such, each of our editors gets a whole blog post to bring you their article of choice – you won’t get that at The Times! (or maybe you would)
So, to kick start us is Els de Vrijer, with her article on Johne’s Disease.
Wet weather increases risk of Johne’s disease
Several studies have been carried out in Scotland recently, which show that the wet weather which has been seen throughout 2012 will increase the risk of Johne’s disease to cattle in the forthcoming year. Rupert Hough, from the James Hutton Institute, recently announced at a conference in Dundee that acidic and wet conditions are likely to increase the risk of the disease spreading. This is because these soils are high in iron and organic matter, providing perfect conditions for the disease to grow and survive in. The scientists took soil samples from eight farms across Scotland, and 75% showed the presence of Johne’s disease. What’s more, the studies have showed that the bacterium which causes the disease can live for up to three years in the acidic soils, whilst bacterium which live in alkaline soils are not likely to survive for longer than one year.
Johne’s disease is caused by the bacterium mycobacterium avium paratuberculosis, and does not only infect cattle, but other ruminants too. The organism is closely related to that which causes tuberculosis in cattle. The presence of mycobacterium avium paratuberculosis causes progressive changes to the intestine. In the lower part of the intestine, the ileum, infected tissues attempt to regenerate and produce healthy tissue, causing a thickening of the intestine lining, preventing nutrient absorption. The main symptoms are therefore profuse diarrhoea and weight loss, but also infertility. The presence of the bacterium can also make the cattle more susceptible to other disease such as mastitis, and causes a significant decrease (10%-25%) in milk yield.
Preventative measures should be taken regardless of the weather, such as rearing young calves separately to minimise risk of contact with adult faeces (calves are very vulnerable to Johne’s disease), and avoiding grazing young stock on land that has been spread with slurry or manure. In addition, from these studies it is clear that improving drainage, using double fencing and liming fields can avoid providing the optimal conditions for this bacterium. Testing for Johne’s disease is essential, as this disease is often fatal and results in massive losses for farmers; it costs the US dairy industry $200-$250 annually.