Narrowing in on Johne’s Disease

This article written by Dr. Reynold Bergen, BCRC Science Director, originally appeared in the February 2019 issue of Canadian Cattlemen magazine and is reprinted on the BCRC Blog with permission of the publisher.

Johne’s disease is caused by a bacterium (Mycobacterium avium paratuberculosis, or MAP) that was discovered in 1895 by a heavily bearded, bespectacled bacteriologist from Dresden named Henrich Albert Johne. When a cow develops persistent, watery, smelly hosepipe diarrhea, and progressively loses weight and body condition even though her appetite is normal and she isn’t running a temperature, she may have Johne’s disease. But it can be hard to know for sure.

Young calves, which are more susceptible to infection than older animals, are often infected with MAP through colostrum, milk or manure. The animal will look perfectly normal, while silently shedding MAP in its own colostrum, milk or manure for a few years before full-blown signs of disease appear. As a result, Johne’s disease is often compared to an iceberg – by the time you see an obviously sick animal, there will be a much larger hidden population of MAP-infected cattle that haven’t become sick yet. Continue reading

Identifying pre-clinical MAP infected cattle


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Mycobacterium avium subspecies paratuberculosis (MAP) causes Johne’s disease, a chronic infectious disease of ruminants. Infection normally occurs in the neonatal period when calves ingest an infectious dose of MAP. The clinical, irreversible and ultimately fatal disease does not occur until years later. In the meantime, animals with preclinical Johne’s disease may look healthy while still shedding MAP in their feces, transmitting the disease to new animals.

There are no effective vaccines or treatments, and diagnostic tests fail to identify many infected animals in the pre-clinical state. Research currently underway and funded by the National Check-off and Canada’s Beef Science Cluster is working to Continue reading

Johne’s disease and the ethical dilemma

This article written by Dr. Steve Hendrick, from the Western College of Veterinary Medicine at the University of Saskatchewan, originally appeared in the February 2013 issue of Saskatchewan Cattlemen’s Connection magazine and is reprinted with permission.

Ever wondered why some cows remain thin while the rest of your herd thrives? Although there are lots of possibilities for this, Johne’s disease is becoming more commonly recognized in Saskatchewan beef herds. Cows with Johne’s disease are typically in their prime (3 to 6 years of age) and often have evidence of diarrhea on their tail. What most producers don’t realize is that Continue reading