BY: SAMANTHA BARTLETT, DVM

Leptospirosis has historically been a higher risk disease in large breed, male herding dogs. The disease is spread by exposure to Leptospira spp. through the urine of reservoir hosts (rodents), primarily in standing water. However, new research shows a changing trend in at-risk populations of dogs.

A study examined trends of dogs diagnosed with leptospirosis in the United States and Canada over the past 40 years. Diagnosed cases peaked in 1971 and then fell in the succeeding years. However in the 1990s and 2000s cases began to climb dramatically. During this time, cases increased in male dogs between 2 and 9.9 years of age that were under 15 pounds.

The researchers are unsure what drove the change in pattern, but speculate urbanization, new Leptospira spp. strains in urban wildlife and vaccination practices may all play a role. The researchers behind the new study did not have information on exposure and vaccination history. This may speak to an inaccurate perception of risk and prevalence of disease leading to inappropriate vaccination practices. Practitioners need to be educated on the regional and seasonal risks of leptospirosis infections in the canine populations they treat.