It’s a diagnosis no cattle producer wants to hear, and it’s likely much more prevalent than we realize.
Caused by Mycobacterium avium subspecies paratuberculosis (MAP), Johne’s causes chronic enteritis (inflammation of the intestine), diarrhea and progressive weight loss in cattle.
Despite the seemingly obvious symptoms in infected animals, the disease has characteristics that can make it difficult to notice, let alone recognize. First, the animal’s appetite tends to remain unchanged until the disease progresses to a terminal stage. Second, though animals are generally exposed as calves (through fecal contaminants or contaminated milk), they generally will not show signs of infection in the first two years of life, and often much longer. Third, it’s estimated that less than five percent of infected animals will develop clinical signs of the disease.
In this interview, Meaghan Crawford talks to Debra Murphy about Johne’s prevention, when to consider testing, and what to do if you find Johne’s in your herd.
And besides being easy to miss, Johne’s is also incredibly difficult to diagnose with certainty.
“The bacteria actually hides in white blood cells in the intestine,” explains Meaghan Crawford, a veterinarian at Dewdney Animal Hospital, in the interview above. “So, effectively hiding from the immune system….and that’s why we don’t really get antibody titers.”
Crawford was a speaker at this year’s UCVM Beef Cattle Conference in Calgary, where she took delegates through a case where animals started showing signs of infection much earlier than is usually expected.
“These animals were otherwise healthy,” she says. “So, they weren’t, you know, not eating, they weren’t off food, they weren’t bloated, they were walking around comfortably, and they looked like nothing else was wrong. But they were very skinny with lots of fecal staining on their tails.”
The animals affected were barely 24 months old when Crawford and her team arrived on the scene, where they realized that they were part of a 300-head herd acquired from three different locations.
Through necropsies and blood tests, the veterinarians were able to confirm Johne’s.
With no treatment options available, and difficulty in acquiring accurate samples/tests, a diagnosis of Johne’s is bleak for any producer. That’s why, suggests Crawford, producers should do everything they can to prevent the disease from entering and spreading through the premises.
Read more on Johne’s Disease via the Beef Cattle Research Council