Safeguarding Your Herd: How Biosecurity Keeps Salmonella Dublin at Bay

Drs. Alex Fonseca-MartinezSamantha Locke and Gregory Habing, Department of Veterinary Preventive Medicine, The Ohio State University

Understanding Salmonella Dublin

Salmonella Dublin is a bacterial pathogen that presents a significant risk to both the dairy industry and human health. While there are many different strains of Salmonella that circulate in livestock, S. Dublin is primarily adapted to cattle and is one of the most commonly identified serotypes from clinically ill animals. Historically, Salmonella Dublin was a herd-health issue in the western United States. In recent years, on-farm outbreaks have occurred throughout the eastern United States and in Canada.

Infection can manifest in various ways, mainly affecting calves aged one week to twelve weeks. Common symptoms include diarrhea, dehydration, unresponsive pneumonia, septic arthritis, and mortality in calves. Diagnosis can be difficult because infected dairy calves, especially older calves, often show symptoms similar to respiratory disease with or without gastrointestinal symptoms. Some calves that survive become long-term, silent carriers that can shed bacteria when stressed. Severe bouts with the disease can also result in unthrifty calves that are less productive in the milking herd or are culled. The primary transmission route for Salmonella is fecal-oral. However, Salmonella Dublin is also known to spread via contaminated colostrum, milk, nasal secretions, and saliva. Establishing effective preventive measures are critical to avoid Dublin introduction to herds or, if Dublin is already present, limit disease spread and resulting negative impacts to animal health and business profitability.

Biosecurity: The Key to Salmonella Defense

The encouraging news is that dairy producers can take proactive steps to protect their herds. Biosecurity practices are not a new concept to most, especially after the COVID-19 pandemic. The use of face masks, frequent hand washing, isolation in case of symptoms, etc., are just some of the biosecurity measures that come to mind when we remember the practices adopted to avoid contracting and spreading the disease. Many of these practices were familiar to animal producers, who had long been using similar methods to protect their animals from diseases. Washing buckets, bottles, trailers, and the use of vaccines are examples of biosecurity elements commonly used by producers to prevent diseases.

Biosecurity encompasses a comprehensive set of measures and management strategies designed to protect animals and humans from the introduction and spread of diseases or harmful biological agents. These practices are crucial for food safety, environmental preservation, and business continuity, ensuring the safety of animals and animal products. There is no single solution to prevent Salmonella from entering or spreading on a farm. Biosecurity offers a comprehensive set of ongoing practices aimed at keeping the disease out (bioexclusion) or contained within the farm (biocontainment).

It's important to recognize that not all farms have the same biosecurity requirements. The level of biosecurity varies based on factors like herd size, farm location, production type, and animal health status. If Salmonella Dublin is present on your farm, establishing excellent biosecurity protocols with the help of your veterinarian, especially in the calving pen and in the rearing of youngstock, will help to control this bacterium. The following elements are part of standard biosecurity procedures to reduce the risk of exposure to Salmonella and other infectious diseases, serving as a minimum requirement for any production facility:

Personnel Training: Ensure that all farm employees are well-trained in biosecurity practices and understand the importance of disease prevention.

Controlled Access: Restrict access to your farm by implementing controlled entry points and visitor protocols, reducing the risk of introducing pathogens.

Animal Housing: If group housing is used in youngstock, utilize an all-in, all-out system to group similarly aged calves together. This can limit the spread of a potential outbreak. When possible, promptly isolate sick calves from the group, providing appropriate care while reducing the chance for animal-to-animal transmission. 

Animal Health Monitoring: Like other Salmonella, Dublin can cause diarrhea in calves. However, unresponsive respiratory disease and swollen joints can also be signs of Dublin infection. Diagnostic testing may be beneficial to confirm S. Dublin presence and inform treatment options. Work with your veterinarian to determine the best treatment protocols to adopt for your operation. 

Calf Feeding: In confirmed Dublin-affected herds, feeding waste milk is an exposure risk for calves. Consider pasteurizing colostrum and waste milk before use. Acidification of milk has also been shown to help reduce transmission risk.

Hygiene Practices: Maintain strict cleaning and disinfection regimens for equipment and animal environments. Consistent cleaning and disinfection in maternity pens are critical to reduce the risk of transmission to calves. Remove and replace soiled bedding regularly and make sure to clean and sanitize equipment such as chains and esophageal tube feeders. In calf barns, clean and disinfect bottles, nipples, and water buckets or troughs daily. Do not power wash facilities or trailers. Power washing may result in aerosolization of S. Dublin and further bacterial spread.

Organize Workflow: If employees cannot be designated to work with calves only, make sure to work with youngstock before moving to the milking herd. Within calf populations, work from the youngest to oldest animals. If possible, work with ill animals last in order to reduce pathogen spread. Clean and sanitize boots when moving between animal pens, barns, or different age groups.

Manure Management: Properly manage and dispose of manure to minimize disease transmission. Consider composting or other safe disposal methods.

Vehicle and Equipment Hygiene: Clean and disinfect vehicles and equipment entering and leaving the farm, including feed trucks and machinery in contact with the herd.

To enhance biosecurity practices, producers can prepare by:

By prioritizing action from the BQA Daily Biosecurity and SMS materials based on your current practices and abilities, dairy producers can reduce the risk of introducing and spreading pathogens. This safeguarding ensures the future of their farms, making biosecurity not just a wise investment but a critical necessity.