Signs, Diagnosis, and Treatment
Clinical signs
Although some dogs infected with Leptospira show either no clinical signs or mild disease, clinical signs generally appear within 7 days of infection. Common initial signs include fever, lethargy, anorexia, and depression.1,2
Within a few days, signs may progress to vomiting and dehydration (signs of renal failure), hemorrhaging, and icterus.2,3 Acute renal failure occurs in 80% to 90% of dogs with significant clinical disease.2 If left untreated, leptospirosis can cause severe kidney and liver damage and the dog may die within days.4
Diagnosis
Early clinical signs of leptospirosis are nonspecific, so diagnosis in dogs depends on detecting leptospires in clinical specimens and/or detecting an increase in antibody titer to at least one of the Leptospira serovars.4 Fresh urine can be tested for the presence of leptospires using darkfield microscopy, but results are often unreliable.3 The microscopic agglutination test (MAT) is the current gold standard4 and most commonly used serologic test for diagnosis.2 The MAT measures antibody titers to Leptospira serogroups, but interpreting leptospirosis titers can be complicated.1 When used in combination with assessment of clinical signs, it is still the most practical means we have today for diagnosing leptospirosis.3
Treatment
Prompt treatment of leptospirosis is indicated to control acute disease and eliminate the carrier state. Administration of intravenous (IV) fluids will support kidney and liver function, helping to alleviate fluid loss and prevent shock.1 In addition, immediate administration of IV antibiotics (penicillin and its derivatives) is needed to kill leptospires in the bloodstream and restore liver and kidney function.1
Reversal of tissue damage caused by leptospires is more likely when antibiotic treatment is initiated promptly after infection is suspected.1 Most dogs will recover within 2 weeks if treatment is prompt.4
As soon as a treated dog is stabilized, oral or IV therapy with doxycycline should be started to eliminate kidney infection and prevent shedding of leptospires in the urine.1,3
References:
- Greene CE, Sykes JE, Brown CA, Hartmann K. Leptospirosis. In: Greene CE, ed. Infectious Diseases of the Dog and Cat. 3rd ed. St. Louis, MO: Saunders/Elsevier; 2006:402−417.
- Kahn CM, Line S, eds. Leptospirosis. In: The Merck Veterinary Manual. 9th ed. Whitehouse Station, NJ: Merck & Co. Inc; 2005:525−529.
- Sherding RG. Systemic bacterial infectious diseases. In: Birchard SJ, Sherding RG, eds. Saunders Manual of Small Animal Practice. 3rd ed. St. Louis, MO: Saunders; 2006:191−203.
- McDonough PL. Leptospirosis in dogs: current status. In: Carmichael L, ed. Recent Advances in Canine Infectious Diseases. Ithaca, NY: International Veterinary Information Service; 2001. Available at: http://www.ivis.org/advances/Infect_Dis_Carmichael/mcdonough/ivis.pdf. Accessed August 8, 2010.
