Biosecurity Against Salmonella in Dairy Calf Farms

What should you know about Salmonella Dublin?

Photo courtesy of CDC

Salmonella are ubiquitous bacteria, which means they are widely distributed in our environment. Within the diverse Salmonella species, numerous subspecies, referred to as serovars, can cause illnesses in both animals and humans. Salmonella Dublin, a serovar adapted to cattle as a host, is an emerging disease of concern to dairy industries. This bacterium exhibits multidrug resistance, making it challenging to treat as there are limited effective antibiotics available. In infected cattle, it can lead to a wide range of symptoms and health issues.

Clinical signs

Salmonella Dublin infection can have many different symptoms and commonly affects calves that are 1 week of age to 1 month of age. Common symptoms include sudden onset of pneumonia that is not responsive to treatment, sudden spikes in death rate, and septicemia. No matter the symptoms, it is often the case that a high number of calves die when the bacteria is first introduced to the farm.

Risk to humans

Salmonella Dublin is also a serious threat to human health. It can infect people and cause illness and death, especially in those with compromised immune systems. The main sources of contamination for humans are through consumption of raw milk or unpasteurized cheese, contaminated beef products, or direct contact with feces from infected animals

Disease transmission in cattle 

There are multiple routes of transmission of this bacteria from a sick individual to a healthy one, the fecal-oral route being the most common. Although S. Dublin can cross the placenta, this is likely to result in abortion rather than the birth of infected calves. For more details about the transmission, consult our fact sheet

Biosecurity: the Key to Salmonella Defense

There is no single solution to prevent Salmonella from breaking out or spreading within a farm; However, biosecurity offers a comprehensive set of methods aimed at keeping the disease out (bioexclusion) or in (biocontainment). Biosecurity can be characterized as a comprehensive set of measures and management intended to protect both animals and humans from the introduction and proliferation of diseases or detrimental biological agents. It is pivotal for upholding food safety and security, preserving the environment, and ensuring the uninterrupted continuity of business operations by safeguarding animals and animal products. In a broader context, it refers to anything designed to prevent the transfer of disease-causing pathogens and can be described using three levels:

  • Structural biosecurity refers to the design and physical construction of the facility such as easy-to-clean surfaces.
  • Operational biosecurity refers to procedures, both on-farm and off-farm, such as how those surfaces are cleaned between animal groups, in addition to sanitation of items before arriving on-site.
  • Conceptual biosecurity is the third level involving the geospatial siting and conceptual design/size of a livestock facility in such a way as to minimize the introduction or spread of disease.

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 bacteria. The elements below are to be implemented as part of normal biosecurity procedures to mitigate the risk of exposure to disease. These basic concepts may be considered the minimum for a production facility.
For more details about Biosecurity consult here
Biosecurity Officer/Biosecurity Manager

Each production site (or integrated system) should have an individual assigned to designing and developing a site-specific biosecurity plan and implementing effective biosecurity procedures. This Biosecurity Officer/Manager is responsible for implementing the plan, training all personnel who enter the premises, and continuously monitoring the procedures for compliance with the plan.

Training of Personnel

Educate all farm personnel about the risks of Salmonella Dublin and the biosecurity protocols in place. Conduct regular training to maintain awareness and compliance.

Line of Separation

An essential component for improved biosecurity is to implement a line or barrier – imagined or physical – separating clean (non-infected) from dirty (potential sources of infection).

Perimeter Buffer Area

Biosecurity plans, particularly plans for livestock raised indoors, may incorporate the Perimeter Buffer Area concept. This peripheral buffer serves to place additional separation between the contaminated and non-contaminated space, and further protect the susceptible animals.

Personnel, Hand Hygiene and Cleanliness

Personnel and their clothing/footwear may become contaminated by disease agents through direct and/or indirect exposure. Farm personnel should practice strict hand hygiene. Provide separate clothing and footwear for areas where cattle are kept. Ensure regular cleaning and disinfection of calf pens, feeding equipment, and waterers.

For more details about cleaning and disinfection procedures (C&D) consult our fact sheet

Vectors – Pets, Wildlife, and Insects

control measures should be implemented to prevent the transfer of disease by wildlife (i.e., wild birds, rodents), feral animals, and insects that can act as vectors.


Biosecurity measures should diminish the opportunity for equipment to serve as a source of contamination. Equipment should be effectively cleaned and sanitized before crossing the Line of Separation


Vehicles are a source of contamination with pathogens from other farms or from other animals. If at all possible exclude vehicles such as feed deliveries, milk haulers, load-out carriers, and employee and visitor cars from crossing the Line of Separation. Vehicles crossing into the protected area of the premises should be thoroughly cleaned and disinfected. Particular attention needs to be paid to wheels and wheel wells. The cargo area of animal transport vehicles needs to be thoroughly cleaned and disinfected between loads.

Carcass Disposal

Carcasses should be disposed of in a manner that protects susceptible animals from disease exposure, particularly from cross-contamination with carcasses from off-site or other processes.

Manure/Litter Management

Manure and spent litter should be removed in a manner to prevent exposure of susceptible animals.

Replacement Animals

Under normal conditions, additions to the herd/flock may be made from offspring born and raised on the operation, which is described as a closed herd. Any replacement livestock from outside the operation should come from herds/flocks with documented biosecurity practices and a history of freedom from infection.

Ideally, animals should be managed as all-in/all-out, meaning groups stay together from the time of arrival, through growth, until they leave for processing. Animals of different groups or ages are not mixed. Between one group leaving and the arrival of the next group, the housing is cleaned, disinfected, and left empty for a period of downtime to minimize the carry-over of pathogens from one group to the next.

Replacement animals should be transported in vehicles cleaned and disinfected (exterior and cargo areas) to minimize the risk of disease transmission from previously transported loads.

Feed, Replacement Bedding/Litter, and Water Supply

Grain, feed, and fresh bedding/litter should be stored and handled so that they cannot be contaminated. Water should come from deep wells or sources that have been treated to eliminate any potential contamination with live pathogens.