Diagnosis: Salmonella Dublin
This dairy has a number of group pens, calves are fed milk replacer with automatic computer controlled feeders. Recently they began having calves in the 7 to 10 day range show signs of diarrhea as well as elevated respiration rates and snotty noses.
Subsequent laboratory testing using tissue samples from a calf that died confirmed the presence of Salmonella dublin. The dairy and their veterinarian are working on a treatment protocol for the sick calves.
This case got me started on reviewing my file on this pathogen. I came across a short article written by Dr. Sheila McGuirk (retired from University of Wisconsin School of Veterinary Medicine) as a response to a reader question for Hoard's Dairyman.
I quote part of Dr. McGuirk's response below. It suggests how hard it is to control the spread of Salmonella dublin once it is present on a dairy.
"S. dublin is unique amongst the other Salmonella bacteria in that it can infect cattle and establish a carrier state in some animals for life. Carrier cattle may not reveal themselves as being sick, but they shed infectious organisms in the environment and, very impactful for calf health, in colostrum and milk.
Along with feces, other bodily secretions of carrier animals discharge infectious organisms, making it very difficult to avoid the exposure of young calves to infection. Oral exposure to Salmonella organisms is common, but for calves that spend more than just a few minutes in a calving area, their skin, naval and feet can be a vehicle for bringing the organism to calf housing." [emphasis added]
Hoard's Dairyman, September 25, 2014
So, now this dairy not only has the issue of how to treat the calves that are already sick, there is the matter of establishing barriers to reduce the numbers of the organism being brought into the calf barn.