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Practical management tips to control Johne’s disease

Johne’s disease pronounced “YONEES” causes a non-responsive diarrhea with severe weight loss in cattle as well as bison, small ruminants (sheep & goats) and camelids. It may last for months and is invariably fatal.

It’s caused by a paratuberculosis organism, similar to tuberculosis, and has a very long incubation period of at least two years. Young calves under three months of age are the most susceptible to first contracting the disease.

Heifer offspring from affected cows should be culled, as they will most likely show clinical signs later in life. With this disease, cattle maintain a voracious appetite but a thickening of the small intestine does not allow nutrients to be absorbed so weight loss is dramatic.

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In winter, a huge manure ball will often be frozen to the tail. If you suspect this disease it is imperative to have the animal examined and verified. By clinical exam and/or testing, your veterinarian can confirm its presence. It is important to identify the reason for poor performance with specific animals in a beef herd. Cows culled early are often mistaken as “hardware cows.”

Practical measures

Producers can follow some very practical guidelines for minimizing its incidence on your beef farm. Johne’s disease has basically a worldwide distribution. The two biggest concerns are the economic losses and culling associated with cows having decreased production, and there is also a human health concern.

If we all were not so wrapped up in thoughts about BSE, Johne’s disease would be our main focus. There has always been concern of Johne’s close resemblance to human Crohn’s disease. Just recently scientists isolated the same paratuberculosis organism from a Crohn’s patient as that causing Johne’s. In the future, producers may need to prove to consumers and world markets we have a low incidence of this disease on our farms.

Spread of Johne’s is primarily the fecal/oral route with exposure to lots of the organisms over time necessary for transmission. Transmission through the milk or transplacentally (through the uterus) has also been demonstrated. The organism has also been isolated from bull semen. Control centers around good manure management, culling appropriate animals and herd testing where necessary.

A real survivor

The organism can survive in moist manure packs for up to one year and is resistant to freezing. Survival in soil or water is greater than one year. Desiccation is effective in killing Johne’s so harrowing pastures is one effective means to minimize its presence. Manure should be spread on grain land not on pasture or hay land. Don’t use the same front-end loader for handling feed and manure without proper disinfection in-between and best to have separate buckets.

Any calving area such as the maternity pen should be disinfected with a phenol-based disinfectant whenever cleaned. Keep feed bunks and watering bowls clean of manure to help break the fecal/oral cycle.

Always buy bulls and replacement cattle from known sources where herd health status is known. Renting bulls and in some cases pasturing in community type pastures always has the possibility of increasing your cattle’s exposure. We are fortunate in Western Canada to spread cattle out for most of the year on pastures minimizing the type of exposure confinement brings. Screen embryo transplant recipients for Johne’s.

Cull affected animals

Culling known cases immediately reduces disease shedding and if done early before severe weight loss occurs they will pass slaughter. Cattle with severe weight loss (body condition score less than two) would still qualify under the BSE testing program and should be disposed of that way.

As noted earlier, review the records of infected cows and cull recent heifer calves, as they are highly likely to contract Johne’s. They talk about the “ICEBERG” theory with Johne’s whereby for every clinical case in your herd there is probably at least 10 more incubating the disease.

The worst-case scenario I have encountered was a small 20- to 30-head herd that was experiencing one to two clinical cases per year. The herd had to be depopulated followed by thorough cleaning and disinfection of facilities as the only way we could eliminate the disease from this premise.

In the future, trading partners may require us to prove we have a low incidence in our herds. In 1998, the Alberta government in co-operation with private practitioners sampled Alberta herds and found 4.4 per cent of herds had at least one positive animal on fecal culture.

I have found in herds we deal with a proper disease control program that includes isolating and then eliminating clinical cases as quickly as possible, removing their heifer offspring and proper manure management, goes a very long way to keeping disease presence to Johne’s at an absolute minimum.

From a human health aspect we must insure a safe product to the consuming public at home and abroad. These fairly simple management changes will facilitate this happening.

About the author

Columnist

Roy Lewis is an Alberta-based veterinarian specializing in large-animal practice. He is also a part-time technical services vet for Merck Animal Health.

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