43 Story Idea? Email Paul.Nolan@Farms.com Better Farming | April 2024 treatment. “If you go out west, it might present more as abortions in cows, and you might also see the issues with calves as well.” There are a few characteristics of Salmonella Dublin that make it a unique point of concern for cattle producers. Dr. Gillian Davidson, a bovine veterinarian at Kirkton Veterinary Clinic who served on the Salmonella Dublin Working Group in Ontario, says that its ability to be carried by healthy-appearing cows is one aspect that makes Salmonella Dublin hard to manage. “It’s a host-adapted serotype, which means it can be carried asymptomatically in cows, and that makes us wary because it could be hiding in plain sight in a perfectly healthy-looking cow,” explains Davidson. “What else is scary is that it doesn’t behave similar to other Salmonella infections. We typically think of gastrointestinal disease when we think of Salmonella, and usually diarrhea is the main sign, but when you get acute infections of Salmonella Dublin in calves, it’s usually a septic infection and respiratory disease. This particular strain is also known to be multi-drug resistant.” Davidson says that transmission of Salmonella Dublin from cattle to humans is also a concern. This could pose a risk to farm workers or people who consume unpasteurized milk. Monitoring As an emerging disease, it’s important that the spread of Salmonella Dublin is monitored. “When you look at the number of dairy farms in Ontario that are affected, it’s still a relatively low percentage,” says Davidson. “It’s not endemic yet; it’s still an epidemic.” Gillies says that each province has their own strategy for monitoring Salmonella Dublin. “Different provinces have their strategies for S. Dublin surveillance, as it has different regulatory classifications across Canada,” explains Gillies. He notes that Salmonella Dublin can be diagnosed through bulk tank milk testing, blood testing, post-mortem assessments, and bacterial cultures. The suitability of the tests will be dependent on whether a producer is looking at an individual animal or the whole herd, as well as the stage of the disease. “If you have an acutely sick animal, really the only way to know if they have it is to take a blood culture. That needs to be taken sterilely by a vet,” says Davidson. “Once an animal has been euthanized or died, a vet can take post-mortem samples. That’s where we find a lot of positives.” Davidson explains that from a surveillance perspective, samples tend to focus on herd-level results rather than the individual animal. This is made more complicated by the length of time required for seroconversion, the time between pathogen exposure, and the appearance of antibodies for Salmonella Dublin infections. “Most of the time, when you get exposed to a pathogen, you can test for antibodies in a matter of weeks,” says Davidson. “When talking about Salmonella Dublin, the seroconversion time is seven weeks, which is a really long time.” This means that while calves are most susceptible while they are young, the best time to test for previous exposure is between four to six months of age. Renaud says that in Ontario, current surveillance efforts focus on bulk tank sampling in dairy herds. A similar approach was taken in British Columbia, with more repeated samples collected than Ontario. Studies from Renaud’s lab also investigated risk factors associated with positive results for Salmonella Dublin at the herd level. Recent surveillance results, which Davidson says found that seven per Livestock So Much Power. So Little Effort. Coragen® MaX insecticide provides fast, selective, extended control* of grasshoppers, bertha armyworms, diamondback moth and cutworms, in a convenient, concentrated formulation. It also works with beneficials** for a one-two punch that keeps the fight going long after you’ve left the field. Controlling damaging insect pests doesn’t have to be a heavy lift. *Depending on rate and when weather and temperature are optimal. **When applied at label rates. In line with Integrated Pest Management and Good Agricultural Practices, insecticide applications should be made when pollinators are not foraging to avoid unnecessary exposure. Always read and follow label instructions. Member of CropLife Canada. FMC, the FMC logo, Coragen and Rynaxypyr are trademarks of FMC Corporation or an affiliate. ©2023 FMC Corporation. All rights reserved. 7937 - WEST - 10/23 7937 Coragen MaX Print Ad_BETTER FARMING_Prairie_Banner.indd 1 2024-02-08 10:19 AM
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