Leptospirosis is a zoonotic disease carried by dogs and several
other wild and domestic animals. The causative agent is Leptospirainterrogans
which has several distinct serovars. The most common serovars
found in dogs are L.icterohaemorrhagiae,L.canicola
and L. grippotyphosa.
TRANSMISSION: Transmission is accomplished
by close direct contact, venereal contact, placental transfer,
biting, or ingestion of infected tissues.
SIGNS: The signs of leptospirosis vary greatly depending
on the animal's age, immune status, environmental factors
and serovarinvolved. Severe disease results from severe leptospiremia,
with fever up to 104(F), shivering, shock and death. Less
severe disease may be seen as fever, dehydration, anorexia,
thirst, vomiting and malaise. Also seen are icterus and progressive
kidney disease with oliguria or anuria. The renal function
may return to normal within three weeks after recovery. The
most common manifestation of leptospirosis is a chronic subclinical
state. Therefore, any dog with a fever of unknown origin or
anterior uveitis of unknown cause should be tested for leptospirosis.
CLINICAL PATHOLOGY: In most cases of leptospirosis there
is thrombocytopenia, leukocytosis and neutrophilia with a
left shift. The BUN and creatinine are increased due to the
renal failure. Electrolyte levels vary according to the
degree of renal failure. There may be increase in ALT, AST,
ALP and bilirubin due to liver damage. Urine analysis may
reveal increased protein and bilirubin.
DIAGNOSIS: The standard serologic method of
diagnosis is a microagglutinationtest. A positive diagnosis
is made by finding a four-fold increase in titer in serial
serum tests taken at two-four week intervals. The first sample
should be drawn before any antimicrobial therapy is begun.
There are also fluorescent antibody and immunohistochemical
tests to identify the organism in tissue. The FA and MC tests
can identify specific serotypes. It is also possible to use
dark-field microscopy to identify the organism in fluids.
This technique requires large numbers of organisms in a very
fresh sample to show a positive result.
Timoney, John F.,etal. Hagan and Bruner's Microbiology
and Infectious Diseases of Domestic Animals.Comstock
Publishing Associates. 1988. pp. 48-57.
Greene,CraigE. Infectious Diseases of the Dog
and Cat.W.B.Saunders Company. 1990. pp. 498-507.
Ettinger, Stephen J. and Feldman, Edward C.,Textbook
of Veterinary Internal Medicine. W.B. Saunders Company.
1995. pp. 373-374.
- Jeff Ambrous,Clin.Path. Clerk, 6/95
- edited by Chris Hanika