Post by AnnB (NE) on May 5, 2010 11:49:44 GMT -5
Just out of curiosity, can anyone tell me what it costs to have a cow checked for Johne's?
My vet told me that for him to come and take the samples for the ELISA would be about $20 per cow. Now, I have to say, after all the research I've done (okay, I'll admit it, I'm writing an article for the Rare Breeds Journal), I don't trust the ELISA, they can be shooting diarrhea all over the place and still show negative on the ELISA.
From what I've found, the Fecal PCR is the most accurate, testing for the DNA of the disease itself.
I've found labs with websites that advertise the Johne's Fecal PCR for $25. My vet will be getting back with me in a few days with what our cost will be per cow to do the Fecal PCR.
But what you have to remember is that one test is NOT foolproof with Johne's. The animal has to be shedding the organism in some quantity before any test can pick it up, and the incubation period is long. The PCR does pick it up first, with no false postives, but at this point, no test can detect an animal that's incubating and not shedding yet. This is why it's actually more important to know the whole herd's test status and the herd's risk status, than it is to have 1 negative test on any particular animal. If the farm is testing, don't turn away because they've had a postive or two, at least they are aware of the disease. But you wouldn't want to buy from someone with a widespread problem.
If the farm is using Johne's Prevention Protocols (keeping calves from being infected by pasteurising colostrum/milk or only feeding milk from a known negative cow, not allowing calves to have any contact with adults, manure, or areas that adults/adult manure have been), and are doing a good job with their manure management, they'll be a low risk. Low risk that a calf born there would have picked up the disease.
But the only way to really be sure of any cow that wasn't raised under the Prevention Protocols is by yearly testing.
Ann B