Dogs, cats, humans, and all other
animals can become infected with different types, or
serovars, of Leptospira.
A contagious bacterial disease of
animals that can be passed on to humans, leptospirosis
affects the kidneys and the liver, causing damage that
can lead to organ failure and death. Typically, rodents
and wild animals are carriers of the disease. Infection
occurs most commonly when the mucous membrane or abraded
skin of an animal or human comes into contact with urine
containing the infective leptospire bacteria.
Once infected, the organism begins to replicate in various
tissues and causes significant infection in the liver and
kidneys, with clinical signs developing within a week of
exposure. Cats tend not to be significantly affected by
leptospirosis. Dogs, however, can develop serious clinical
disease, although not all canines with leptospirosis will
show clinical signs of infection. In fact, many animals
that have this disease will be asymptomatic or will have
chronic or mild symptoms.
Animals can transmit leptospirosis to their owners. People
who suspect that they have been exposed to infection should
consult a physician.
Clinical signs include anorexia, muscle
soreness, depression, tachypnea, vomiting, fever, anemia,
pale mucus membranes, dehydration, weakness, diarrhea,
stiffness, tachycardia, epistaxis, petechiae, melena,
coughing, dyspnea, polyuria and polydipsia becoming anuric,
weight loss, ascites, and signs of hepatic encephalopathy
due to liver damage.
Clinical signs may include loss of
appetite, depression, increased respiratory rate, sore
muscles, vomiting, fever, anemia, pale mucous membranes,
dehydration, difficulty breathing, weakness, diarrhea,
dark and tarry stools, increased drinking and urinating,
jaundice from liver disease, bleeding from the nose,
kidney failure, and death.
Leptospires are tiny, moving spiral
bacteria called spirochetes that are found worldwide.
Different types of Leptospira can cause disease
in animals and humans. Dogs tend to develop leptospirosis
from L. australis, L. autumnalis, L.ballum, L.
bratislava, L. braviae, L. canicola, L.
grippotyphosa, L. harjo, L. icterohaemorrhagiae, L.
pomona, and L. tarassovi forms of the bacteria. L.
canicola, L. grippotyphosa, L.pomona,
and L.bratislava can infect cats. Infections appear
to be more common in warm and moist climates, in standing
water that is neutral to slightly alkaline pH, and in
areas where animals are closely housed, such as kennels
and urban settings. In addition, exposure to wildlife
and rodents that can carry the bacteria is a significant
risk factor.
If leptospirosis is present, a complete
blood count, or CBC, may show evidence of dehydration,
anemia, low platelet numbers, and increased or decreased
numbers of white blood cells. A chemistry panel will
detect evidence of kidney failure or liver disease. In
addition, specific diagnostic tests are available that
will detect exposure to Leptospira, such as a
test that will examine a blood sample for antibodies
to the disease. Before antibiotic drugs are given, the
organism can be cultured from urine, blood, kidney or
liver tissues.
For animals that have acute, severe
disease, the prognosis is guarded. Most animals, however,
have subclinical or asymptomatic disease, or chronic
disease. These animals have a fair to good prognosis.
Leptospires are passed in the urine
of infected animals. Infection occurs when the organism
in the infected urine penetrates abraded skin or the
mucous membranes. In addition, the ingesting of urine
in contaminated food, water, or soil can transmit leptospirosis.
Transmission also has been known to occur through a bite
wound, through the placenta to an unborn animal, and
through venereal contact.
Life-threatening complications of
leptospirosis should be addressed immediately. Because
this organism typically affects the kidneys, the use
of intravenous fluid therapy is essential. The use of
intravenous antibiotics, such as penicillin and dihydrostreptomycin,
is needed during the initial treatment phase. Oral antibiotics
are prescribed after the animal has begun to recover.
Precautions and proper hygiene should be instituted in
order to prevent human infection.
A vaccine is available that provides
protection to the more common types of Leptospira bacteria.
Dogs in areas of risk should receive three vaccines,
given three to four weeks apart; from that time on, they
should receive vaccines on a yearly basis. Other prevention
steps include keeping rodents away from the animal's
environment, since rodents often are carriers of the
bacteria. In addition, animals should be kept away from
areas in which the bacteria thrive, such as stagnant
water, marshes, ponds, and muddy areas. Humans should
avoid contact with the urine of animals.
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