Challenges of Getting A Lepto Diagnosis
Read the first part of this article, "Is Leptospirosis Lurking?"
Less than half of abortions occurring in beef herds receive a diagnosis, either because producers don’t submit samples or the sampling and handling methods were inappropriate, says W. Mark Hilton, DVM, technical consultant with Elanco technical services.
Producers should communicate with their veterinarians to understand strengths and weaknesses of lepto tests and to ensure they collect and submit the proper samples when abortions occur.
Since the introduction of vaccines that protect against the serovar Hardjo strain about a decade ago, cases of leptospirosis in cattle have declined, says , Dan Grooms, DVM, Michigan State University.
However, once a veterinarian has ruled out other causes of a reproductive problem, he encourages them to be persistent in pursuing a diagnosis. Submit samples from multiple abortions if possible, he says, noting it sometimes takes several to find a positive result.
In diagnosing reproduction problems, Grooms stresses veterinarians need to remember to look at the big picture first, then narrow down toward specific details, rather than vice-versa. Use all the tools available, including epidemiology, herd records and diagnostic testing.
Where lepto is diagnosed or strongly suspected, the veterinarian and client can look for sources of the pathogen, such as herd introductions or exposure to other animal carriers. Grooms cites a recent case where a high percentage of cows in a beef herd aborted at six to seven months of gestation. Diagnostic testing confirmed leptospirosis. The herd had not experienced problems in the past, and thus was not well vaccinated. Investigators found two weeks before the abortions began, the producer started feeding from a hay pile that was contaminated with raccoon feces and urine. Even in well-vaccinated herds, Grooms says, a high level of exposure can overcome the protection from vaccination.
Control of leptospirosis in cattle requires a comprehensive approach that includes reducing the risk of Leptospira exposure, vaccination, and selective antimicrobial treatment to clear carriers of serovar Hardjo when indicated, Grooms says.
But when fertility problems crop up, don’t jump to conclusions. Paraphrasing Kansas State University veterinarian Brad White, Hilton says reproductive problems usually result from an accumulation of errors. “Eliminate the common before focusing on more difficult issues such as lepto,” Hilton says.
