Salmonella dublin: Bulk Tank Testing


Source: SaskMilk

As you are aware, the bulk tank from every dairy in the province has been tested for Salmonella dublin. The purpose of this article is to explain what the results mean, what you can do if you are positive and what the next steps are for all herds.

Bulk tank results

The bulk tank test detects antibodies against Salmonella dublin that are present in milk. Antibodies are produced when an animal is exposed to Salmonella dublin. If an animal has more antibodies, it is likely that the exposure is more recent, or the animal is actively infected. Therefore, if the bulk tank is positive, it is likely that Salmonella dublin is present in the herd. If the bulk tank is negative, it does not guarantee that the herd is free. Further testing is needed in both situations.

What to do if the bulk tank test result was positive?

If the bulk tank test result was positive, it is very important that you consult with your veterinarian. There are many ways in which Salmonella dublin can spread throughout the herd. The main route of transmission is from adult cows to calves through feces and unpasteurized milk so control measures will focus on calving and young calf management. Your veterinarian can accurately evaluate the risk factors for transmission and can work with you to prioritize management changes that will have the greatest impact in your situation. This will give you the best chance of bringing it under control.

If your bulk tank is positive, be aware that Salmonella dublin can infect humans. It is resistant to most available antibiotics so infection in humans is very serious. The most common route of transmission is by drinking unpasteurized milk. Positive herds should pasteurize milk intended for consumption on-farm. Different people have different degrees of immunity and you protect your families by pasteurizing the milk you consume at home. Always wash your hands after handling animals. Outerwear and boots intended for the barn should remain in the barn.

Further testing

Directions for further testing will be provided by SaskMilk. These tests will involve collecting blood samples from up to 10 calves. The samples will be again be tested for antibodies. The reason for testing calves of a certain age range is that these animals are the most likely to be positive for Salmonella dublin if it is present in the herd. To ensure the greatest accuracy of testing, it is important to record the ages of calves tested. If less than 10 calves are available in the appropriate age range, then all calves in that age range should be sampled.