Update on Leptospirosis

Dr. Katharine Lunn: Over the last 10 years, the typical leptospirosis case that we have seen at the University of Wisconsin is a dog in acute renal failure. Case reports from Massachusetts, New York, New Jersey, Michigan, Georgia, and Wisconsin all suggest the same: Acute renal failure is now the most commonly reported presentation of canine leptospirosis. These reports document that the clinical disease is usually due to infection with the serovars grippotyphosa, pomona, or bratislava. Clinical signs usually include anorexia, lethargy, vomiting, fever, stiffness, abdominal pain, polyuria, and polydipsia. Renal failure is the predominant finding in these patients, with a small percentage also showing evidence of liver disease (icterus and elevated liver enzyme activities). Infection with the canicola and icterohaemorrhagiae serovars is much less common now, probably due to vaccination. So we see fewer dogs with classic leptospirosis—a combination of liver and renal failure. I would also consider leptospirosis in the differential diagnosis of uveitis in dogs. A word of caution: A dog with uveitis at the University of Wisconsin was subsequently found to have leptospirosis. Because the index of suspicion was low (the dog had no other signs), appropriate precautions were not taken. The student managing the case developed clinical signs of leptospirosis, which fortunately were mild. Leptospirosis can also present as polyuria and polydipsia in dogs with no other clinical or biochemical abnormalities. These dogs have isosthenuria or minimally concentrated urine. Leptospirosis serology is now always on my plan for the workup of polyuria and polydipsia in dogs.