Leptospirosis
Leptospira interrogans is shaped like a question mark and
is a special type of bacterium called a spirochete.
When a dog becomes infected
Dogs become infected by leptospires when abraded skin comes into contact with the
urine of an infected host. The organisms quickly spread through the bloodstream
leading to fever, joint pain, and general malaise which can last up to a week.
The organism settles in the kidneys and begins to reproduce, leading to further
inflammation and then kidney failure. Depending on the type of leptospire involved, other organ failure (especially liver)
can be expected as well. Make no mistake, leptospirosis is a life-threatening disease.
TYPICAL SYMPTOMS: Fever,
depression, loss of appetite, joint pain, nausea, excessive drinking, jaundice,
excess bleeding brought on by low platelet count.
PEOPLE
CAN BECOME INFECTED, TOO!
The infection in humans
As the Centers for Disease Control and
Prevention monitor leptospirosis cases in people it
seems that one third come from contact with infected dogs and one third come
from contact with rats (usually through field work). The same disease
symptoms occur in humans as would be seen in a canine infection.
About the Organism
The species Leptospira interrogans has been classified into subtypes called SEROVARS. Over 200 serovars have been
named.
Testing
Blood testing to detect antibodies against
Leptospira interrogans
(“microscopic agglutination testing”) can be performed. While a value of
1:800 or higher is supportive of a positive diagnosis, confirmation is not made
until a second antibody level ( called a
titer) is run between 2 & 4 weeks and
shows a four fold increase. Vaccination may interfere
with testing since obviously the entire point of vaccination is to generate
antibodies. If the dog has been
vaccinated in the last 3 months, testing will be difficult to interpret;
however, a single titer of 1:800 or higher against a serovar
for which there is no vaccine is considered a positive result. The PCR test, which amplifies small amounts of DNA, would be an
excellent test if vaccination has been recent but PCR testing is not available
in most reference laboratories.
Urine may be submitted for what is called Darkfield Microscopy. In this
test, a dark background may offset the paler leptospire
organisms rendering them visible. This sounds like a good way to make the
diagnosis but the problems are
- the urine sample must be
fresh and most animal hospitals do not have the capability to do dark
field microscopy
- Leptospires
are only shed in urine intermittently.
The kidney may be biopsied and
special tissue stains may be used to detect leptospire
organisms. Obviously this is an invasive procedure.
Treatment
Fortunately, Leptospira
interrogans is sensitive to penicillin, a
readily available antibiotic. After penicillin has been used to stop leptospire reproduction and limit bloodstream infection, tetracycline derivatives are used to clear leptospires from the kidneys. Since tetracyclines
and penicillins are not a good concurrent
combination, often a combination of a penicilin with
a fluroquinolone type antibiotic (such as enrofloxacin) is used to cover both phases of the
infection.
Intravenous fluids are crucial to support blood flow
through the damaged kidneys so that recovery is possible. Any areas at home
that have been contaminated with urine should be disinfected with an iodine
based product and gloves should be worn in cleaning up any urine. Prognosis is
guarded depending on the extent of organ damage.
Vaccination options
VACCINATION REACTIONS
ARE COMMON!
Vaccination against Leptospira
interrogans is only available for the serovars called canicola,
grippotyphosa,
Vaccination against the four serovars
mentioned is commonly included in the basic distemper shot (DHLPP - the “L”
stands for “leptospirosis”). The vaccine can be
made up to omit the leptospirosis portion. Of all the
sera in this basic vaccine, it seems to be the leptospirosis
portion that is associated with hives, facial swelling, and even
life-threatening vaccination reactions much more than any of the other
fractions. If there is any question of an animal having a vaccine reaction, leptospirosis vaccine is left out of the mix.
Vaccination will reduce the severity of disease but will
not prevent infected dogs from becoming carriers.
We carry the Leptovax 4 vaccine
by from