Today's Veterinary Practice

JAN-FEB 2018

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77 JANUARY/FEBRUARY 2018 ● TVPJOURNAL.COM CLINICAL INSIGHTS MAT titers performed by the same laboratory revealed a 4-fold decrease in the serovar Grippotyphosa (1:400), further supporting the diagnosis of leptospirosis. DISCUSSION: OVERVIEW OF LEPTOSPIROSIS Pathogenesis Leptospirosis is a bacterial disease with a worldwide distribution and is of importance in human and veterinary medicine due to its zoonotic potential. 1,2 Naming conventions for leptospiral pathogens are unusual, as the organisms are commonly described by serovar names, rather than species names. There are hundreds of known serovars of the genus Leptospira, and disease in dogs is caused by the pathogenic serovars of the species Leptospira interrogans and Leptospira kirschneri. 2,3 Different serovars are adapted to various reservoir hosts, including the raccoon ( FIGURE 2 ), opossum, vole, and rat; the dog is likely the reservoir host for serovar Canicola. 1–3 These hosts excrete the organisms in their urine. Incidental hosts, such as humans and dogs, are infected when their intact mucous membranes or abraded skin comes into direct or indirect contact with infected urine. 1,2 Leptospires prefer a warm and wet environment, therefore, disease is found more predominantly in warmer climates with higher annual rainfall. 1,2 The incubation period ranges from a few days to a week and varies based on infecting dose, strain, and immune response of the host. 1 Clinical Findings Disease may manifest as peracute disease or subclinical infection, with the severity of clinical illness depending on infecting strain, geographical location, and immune response of the host. 1,2 Common clinical presentations include lethargy, anorexia, vomiting, abdominal pain, or changes in urination (polyuria, oliguria, or anuria). 2,4 Leptospirosis should be suspected in dogs with evidence of febrile renal or hepatic disease, vasculitis, uveitis, or pulmonary hemorrhage ( TABLE 5 ). 1,2 Most consistent hematologic findings include leukocytosis, anemia, and thrombocytopenia. Biochemical abnormalities reflect renal damage and reduced glomerular filtration rate (azotemia, hyperphosphatemia) and/or hepatic injury (hyperbilirubinemia, elevated liver enzyme activity). 2,4 Bleeding tendencies are likely multifactorial in origin, reflecting both vascular and hepatic injury. Although attempts have been made, no consistent correlation between infecting serovar and clinical presentation has been identified. 1 This is likely at least partly attributable to the inability of antibody tests to predict the infecting serovar. 1,5 Definitive Diagnosis There is no single "gold standard" test for an antemortem diagnosis of canine leptospirosis. The diagnosis is based on the combination of clinical FIGURE 2. The raccoon is an important reservoir host for leptospirosis. TABLE 5 Common Clinical Syndromes and Manifestations Associated With Leptospirosis CLINICAL SYNDROME CLINICAL MANIFESTATIONS Renal failure Polyuria, oliguria, or anuria Polydipsia Abdominal pain Dehydration Azotemia Hyperphosphatemia Hepatic injury Icterus Cranial organomegaly Coagulopathy Hyperbilirubinemia Elevated liver enzyme activity Vasculitis Peripheral edema Pleural effusion Peritoneal effusion Petechiation Epistaxis Uveitis Pulmonary hemorrhage syndrome (appears to be more prevalent in European cases)

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