Infectious Disease. Johne’s Disease (Paratuberculosis). Causative agent: Mycobacterium paratuberculosis Extremely slow onset, chronic, progressive, incurable, fatal minimum 18 months to clinical status incubation period up to 10 years Prevalent in 20% of US herds
“Johne’s disease is not at all widespread.
It does occur, however, and as the years go by it will become more and more common and will places a great tax on the cattle industry”
Beach and Hastings 1922
Fig 35-1. Cows with Johne's disease typically lose tremendous amounts of body weight, although feed consumption may be normal (Courtesy of Mark Kirkpatrick)
Fig 35-2. Enzyme-linked immunosorbent assays (ELISA's) are a useful diagnostic tool for estimating the prevalence of Johne's disease in infected herds (Courtesy of Mark Kirkpatrick)
Fig 35-3. To confirm infection with Johne's disease, tissues can be stained for the immunohistological detection of M. paratuberculosis (Courtesy of Mark Kirkpatrick)
Crohn’s disease is a bowel disease in humans
Overall incidence 5.6 cases per 100,000
Severe and very unpleasant condition
Cause unknown, maybe infectious agent like Mycoplasma
Johnes organism found in Crohn’s patients
No firm link established, the evidence is still inconclusive - but the issue is a source of concern to the dairy industry
Fig 35-4. Obtaining an ear notch tissue sample for immunohistochemical diagnosis of BVD infection (Courtesy of Mark Kirkpatrick)
Fig 35-5. Immunohistochemical techniques help veterinarians visualize the BVD virus in ear tissue (Courtesy of Mark Kirkpatrick)
Is there a source of C. perfringens type A (human model)?
Carbohydrate engorgement or presence in small intestine in high amounts.
Rumen emptying rates, local hypomotility?
Serum Ca levels?
Wet vs. Dry
Fineness of Grind
Vaccination with a 7-way Clostridial bacterin/toxoid has shown little effect.
C. perfringens C&D toxoid may have some effects if the infection was mixed.
Carbohydrate availability visualize the BVD virus in ear tissue (Courtesy of Mark Kirkpatrick)
Rumen Emptying Rate?
Ca Levels, DMI or Acidosis