Leptospira is a gram negative spirochete
bacterium that is very common in the United States. There are over
250 different subtypes and it is a disease people can get. There has
been increased prevalence of Leptospira disease since 1983,
due to the urbanization of rural areas and increasing contact
between dogs and wildlife.
Leptospira penetrates through the mucosal
membranes-eyes, conjunctiva, mouth, and any breaks in the skin.
After disseminating in the blood, Leptospira tends to target
the liver and kidneys but can also go to other organs in the body
such as the spleen and central nervous system.
Dogs, rats, pigs, cattle, raccoons, deer, skunks,
possums, and small rodents can serve as reservoir hosts for the
different serovars. A reservoir host is an animal that harbors the
organism with no clinical signs of disease. Man and dog can be an
incidental host, in which clinical disease occurs, but the organism
is not shed in high quantities.
The most common route of disease transmission is
indirect through contact with stagnant or slow moving water
contaminated by urine. The disease is shed in high quantities in the
urine. Leptospira organisms are able to survive for long
periods in surface water. Transmission can also occur by direct
contact with infected urine.
Leptospirosis can cause kidney failure,
inflammation/toxicity of the liver, inflammation of the blood
vessels causing hemorrhage, inflammation of muscle tissue, and
abortion in food animals.
Prevalence of the disease varies markedly and
usually correlates with the rainfall and warm weather. Incidental
host infections can be either sporadic or epidemic. The organism can
live for long periods of time in warm water. Freezing will kill it.
It is endemic in the wildlife population with infection rates as
high as thirty to forty percent.
In dogs, the incubation period (time from
exposure to signs of clinical disease) varies between three and
twenty days. The most common early signs of disease early are
anorexia, lethargy, vomiting, and fever. Other symptoms include
weight loss, increased drinking and urinating (polydipsia/polyuria),
diarrhea, abdominal/lumbar pain, icterus/jaundice,
stiffness/reluctance to walk (myalgia), enlarged kidneys (renomegaly),
small areas of hemorrhage (petechia) or sometimes severe hemorrhage,
and low platelet count (thrombocytopenia).
Prognosis depends upon how early treatment
begins. Diagnosis of this disease can sometimes be difficult as
several different conditions can look similar. Up to 25 percent of
infected dogs will not survive the initial infection. From 33 to 40
percent of infected dogs develop chronic renal failure.
Leptospira bratislava and L.
icterohemorrhagia were the leading serovars causing disease in
the mid-1970s. Since the mid-1990s, L. grippotyphosa and
L. Pomona are the leading infectious causes of acute renal
failure in dogs.
Prevention in animals:
Avoid exposure
Isolate suspected cases in the hospital
Quarantine carriers (shedders) in the home or
kennel
Vaccination
Vaccination of dogs for Leptospirosis has
been a controversial issue for the past several years. Early
vaccines protected against strains L. Bratislava and L.
canicola, but there is no cross protection between the various
serovars in vaccines. It was also suspected that older Leptospira
vaccines caused a large number of vaccine reactions. It has been
determined that it was the cellular debris in the vaccine
(contaminants) and not the Leptospira which caused the
reaction. A new vaccine that protects against the four most common
serovars: L. grippotyphosa, L. Pomona, L.
icterohemorrhagia, and L. canicola is now available.
Who should be vaccinated? It is recommended that
all dogs be vaccinated because of the zoonotic potential of the
disease. It is recommended that dogs used for hunting and working,
dogs taken camping, dogs living in rural/farm areas, and dogs with
access to ponds, lakes, or drainage ditches be vaccinated. Dogs
housed where there are problems with rodents, raccoons, and wildlife
exposure should also be vaccinated.
Vaccines protecting against viral diseased, such
as parvovirus and distemper, are given once every three years after
an initial puppy series and booster vaccination one year later.
Unfortunately, Leptospira is a bacterum, not a virus, and the
vaccine needs to be given more frequently initially. Leptospira
vaccine should be given two times at three weeks apart and then
twice annually. Those dogs that received the older Leptospira
vaccine should still receive the two boosters of the newer vaccine
because of the added serovars.
Call me with any questions or concerns, or visit our website,
wilsonvet.com. My phone number at Wilson Veterinary Hospital is
408-353-8164.
