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Research   »   Johne's Disease

Johne's Disease

Johne’s disease (pronounced “Yo-knees”), also known as paratuberculosis, is a long standing  infection that causes a very gradual thickening of the intestines reducing the nutrients the cow can absorb, resulting in weight loss, diarrhea and eventually death.  Johne’s disease primarily affects cattle and other ruminants, but has also been reported in pigs.

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Johne’s disease is caused by the bacterium Mycobacterium avium subspecies paratuberculosis (MAP). It typically harbors and multiplies in the small intestine. MAP can also be spread to areas outside the intestine, such as the uterus, lymph nodes, udder, reproductive organs of bulls, and may be excreted directly in milk or semen.

Several therapies have been investigated, but unfortunately no treatment has been found to be effective and economical for Johne’s disease. This is partly due to the fact that there is an extremely long dormant period between infection and clinical disease. Complicating the issue further is the lack of accurate tests to properly identify infections, particularly those in early development.  

Impact on Canadian Cattle Herds

Researchers estimate that from 1 to 2% of mature Canadian beef cows and 2 to 9% of Canadian dairy cows may be infected with Johne’s disease. The difference in incidence rates between beef and dairy herds may be related to differences in calf management and because beef cattle generally range over larger areas and have less exposure to other cattle’s feces than dairy cattle.  However, dairy cattle are important to the beef industry because most end their careers as lean beef.

Cows with Johne’s disease, in the last National Animal Health Monitoring System survey of beef cattle in the United States, have been shown to wean calves that weigh 50 pounds less than normal herd mates.  This production loss often goes unnoticed.  The disease also affects margins at purebred operations selling bulls and replacement females, increases feed costs and reduce animal longevity.

Cows with Johne’s disease have been shown to wean calves that weigh 50 pounds less than normal herd mates.


Infection with MAP is thought to predominately occur when calves are less than 6 months of age but animals in infected herds probably receive multiple doses of MAP.  It is estimated that only 1/3 of young animals with a single exposure to MAP will develop chronic infections.   Research has also demonstrated that as cattle get older, a larger dose of MAP is required to cause infection.

Calves are commonly infected through ingestion of MAP in contaminated feces, milk or colostrum. MAP has also been found in the reproductive tract of infected animals but the risk of sexual transmission is believed to be extremely low.

Several environmental factors affect the survival of MAP.  MAP does not multiply in the environment, but it can survive for over a year, even through Canadian winters.  It is also very difficult to kill with common disinfectants and heat (both pasteurization and cooking).

Calves are commonly infected through ingestion of MAP in contaminated feces, milk or colostrum.


Although infection usually occurs during early life, clinical signs do not appear until much later.   The onset of clinical signs most commonly occurs between 2 to 6 years of age.   The amount of MAP and age at infection are considered to be the two main factors that determine when clinical signs appear.  Many infected cattle will shed MAP through their manure before showing any signs of infection.

 Johnr'd Disease timeline in cattle

Once clinical signs appear, they are characterized by periodic to persistent diarrhea and progressive weight loss, both of which are non-responsive to treatment.   An increased appetite may occur initially, but usually progresses to anorexia.   In time, animals become very weak and lethargic, and if not culled they will become recumbent and die.   

Vaccination, Diagnosis, and Treatment

The diagnostic tests that are currently available do not reliably detect many infected animals until they are shedding large numbers of MAP. As a result, efforts to eliminate Johne’s disease using “test-and-cull” methods have been unsuccessful. By the time an animal is confirmed to be infected, it has had the opportunity to spread the infection to other susceptible animals in the herd.

There is no vaccine currently licensed or available in Canada as they interfere with tuberculosis testing and have limited efficacy.

Diagnostic tests are unreliable, there is no vaccine available in Canada, and there are no effective drugs for treatment of Johne’s Disease. Prevention is key.

Similarly, there are no effective drugs for treating cows with Johne’s disease; antibiotics licensed for use in cattle do not kill MAP. Monensin (Rumensin™), an antimicrobial currently used to prevent coccidiosis, has been found to reduce the shedding of MAP in the manure of infected cattle and may be one part of a Johne’s control plan.

The beef and dairy industries continue to invest in research to develop better vaccines and detection methods, because effectively overcoming these shortcomings would greatly improve our ability to combat the disease effectively.

Prevention and Control

There is no quick-fix for Johne’s disease. Preventing and reducing Johne’s disease requires a combination of management practices to avoid introducing infected cattle, colostrum or manure into the operation, and calving, feeding and grazing management practices that reduce the risk that young calves will consume infected manure and colostrum.  The worst mistake a producer can make is to separate a Johne’s infected cow and keep her in the calving area in hopes that she will gain weight before being sold.

Producers should work with a trained veterinarian to examine the herd’s Johne’s disease history, conduct a risk assessment of current management practises related to the spread of MAP, and develop a plan to implement the most appropriate measures to minimize Johne’s disease in that particular herd.

Preventing Johne’s disease has broad benefits.  Management changes that decrease the risk of Johne’s disease will also reduce exposure to other, more common calfhood diseases (particularly calf scours), improve the effectiveness of vaccines for calfhood diseases, and improve overall herd health, performance and efficiency.

To prevent the spread of Johne’s disease:

  • Reduce manure build-up of pens and pastures where late-gestation cattle are kept.
  • Keep the calving area clean at all times and maintain a low cow density in these areas.
  • As soon as bonding has occurred, move cow-calf pairs to a clean pasture.
  • Avoid exposing calves to manure build-up by frequently moving location of feedbunks, waterers, and creep-feeders.
  • Once calves are weaned, do not put them on pastures used by cows.
  • Calve first-calf heifers in a separate location from mature cows.
  • Use separate equipment for handling manure and feed.
  • Do not spread manure on land used for grazing, esp. for young stock.
  • Purchase replacement animals only from test negative herds and when this is not possible assess herd status through owner and veterinarian statements.
  • Only purchase commercial colostrum supplements from a company that uses production methods that destroy MAP. (i.e. The Saskatoon Colostrum Company)
  • Cows that show symptoms of Johne’s disease should be removed from the breeding herd, along with their daughters, as they were likely infected through colostrum.
  • Responsible management of stock water, grazing, manure and runoff can further reduce the possibility of spreading Johne’s disease to other cattle, neighbouring herds, wildlife and the environment.
  • Ionophores may reduce MAP shedding and reduce the risk that new animals will become infected.
  • Rotational grazing is less risky than continual grazing.
  • The role of wildlife is very unclear, but one study suggests that having dogs that keep wildlife off the yard reduced the likelihood of MAP infection.

Download the Canadian Johne's Disease Initiative brochure for more tips.

Relation to Crohn’s Disease

Johne’s disease has distinguished itself as a disease of importance not only due to the economic losses associated with limiting production on-farm and world trade, but also as a potential threat to humans.  The symptoms of Johne’s disease in cattle are similar to those of human Crohn’s disease, and MAP has been isolated from some Crohn’s patients. This has led some scientists to suspect that MAP may play a role in both diseases. Other scientists argue that patients who are severely ill with Crohn’s disease are more susceptible to infection by many other organisms, including MAP. This argument has not been settled by the scientific community because no causal relationship between MAP and Crohn’s disease has been found.

To the best of our knowledge, neither the World Health Organization nor any individual nation has declared Johne’s to be a zoonotic disease (a disease that can impact both animals and humans). Despite this fact, misinterpreted and misguided information can have serious consequences for the beef industry.

The Canadian Johne’s Disease Initiative

There are clear risks for consumer confidence and international trade if the potential link between Johne’s and Crohn’s disease is confirmed. To ensure that Canada is less vulnerable to these risks, Canada’s beef and dairy industries have developed a new program to combat Johne’s disease, even though current vaccines, treatment and diagnostic options are not ideal. This initiative is led by the Canadian Cattlemen’s Association (CCA), Dairy Farmers of Canada (DFC), and the Canadian Animal Health Coalition (CAHC), with expert input from Johne’s disease researchers and support from the federal and some provincial governments.  For more information on the Canadian Johne’s Disease Initiative, visit the CJDI page on the Canadian Animal Health Coalition website.

Future Research Considerations

While much research has been conducted to understand MAP and Johne’s Disease, much of it has been done on dairy cattle.  Further research specific to the beef industry will better enable producers to develop effective and efficient control programs and reduce any negative impacts MAP has on affected farms and on the entire industry.  

Learn More

To learn more on this topic, see the fact sheets posted on the right side of this page. External resources are listed below.

Literature Review of Johne's Disease in Beef Cattle [PDF]
Steven Hendrick, DVM, DVSc and Dale Douma, DVM

Canadian Johne's Disease Initiative
Canadian Animal Health Coalition

Canadian Johne's Disease Initiative Brochure
Canadian Animal Health Coalition

Canadian Beef Cattle On-Farm Biosecurity Standard Implementation Manual
Canadian Food Inspection Agency

Johne's Information Central
National Institute for Animal Agriculture

Johne's Education and Managment Assistance Program

Johne's Information Centre
University of Wisconsin


Feedback and questions on the content of this page are welcome. Please e-mail us at info [at] beefresearch [dot] ca.


Thanks to Dr. Steve Hendrick for assisting with this page.

This topic was last revised on June 29, 2018 at 2:06 AM.

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