This article was written by a local vet,in the local magazine.Cows with Johne's disease are typically in there prime,3 to 6 years of age-and often have evidence of diarrhea on there tail.What most producers don't realize is that infection often begins when a calf is exposed to contaminated manure.The bacteria causing Johne's disease results in a very gradual thickening of the intestines,reducing the nutrients the cow can absorb,resulting in weight loss and diarrhea.The worst mistake a producer can do is keeping her anywhere near the calving area.Cows with signs of Johne's disease shed billions of bacteria through there manure and serve as a major source of infection for future calves.It has even been shown that cows infected with Johne's will periodically shed bacteria up to a year before they ever show any signs of having the disease.Further complicating the spread of Johne's is that the bacteria may also be passed through colostrum,milk and even to a unborn calf.The bacteria causing Johne's does not multiply to any extent outside of the cow,but is very hardy and can survive over a year in the enviroment,even through a saskatchewan winter.Cows with Johnes were shown to wean calves that weigh 50 pounds less than normal herd mates.As an industry,the reason for concern with Johnes diesease is not just it's production effects,but its risk as a cause of human disease,as well.It is very likely that some cases of Crohn's disease in people are assosiated with the bacteria causing Johne's in cattle.Not only do the diseases appear similiar in clinical signs,but even the damage in the gut.Testing for Johne's disease can be an exercise in frustration.The tests do what they were designed to do-identify the bacteria or cows immune response against it.However the bacteria in manure or antibodies in the blood may not be present until late in the disease.Typically for infected herds,a positive test result is indeed positive,but a negative test result means keep looking.We estimate that that at least 1 in 10 beef herds are infected with Johne's disease.However,the number of cows infected in a herd will depend on it's management.Confining cow-calf pairs in small corrals or on pasture will increase the risk of calves getting exposed to infected manure.Just remember that controlling Johne's disease uses some of the basic management used to control calf-scours-reduce exposure to cow manure by giving cow-calf pairs as much room as possible;use lots of bedding to cover and dilute the manure(dilution is the solution to pollution),if possible,fence off any standing water that becomes heavily contaminated with manure,and culling cows with poor udders or no milk.Strategies like these will help keep cows and udders clean and minimize calf exposure to manure,while getting them sufficient colostrum and milk.There is no vaccine currently licensed or available in canada as they interfere with tuberculosis testing and have limited efficacy.Similarly,there are no effective drugs for treating cows with Johne's disease.Monensin (Rumensin TM)is an antimicrobial currently used to prevent coccidiosis,but it has also been found to reduce the shedding of the Johne's bacteria in the manure of infected cattle.It may be one part of a Johne's control plan.That is the article in short,my hands are getting tired of typing.
