|
CANINE LEPTOSPIROSIS
|
|
Leptospirosis2
Leptospirosis and your pet
Leptospirosis in Dogs
THE PET HEALTH LIBRARY
By Wendy C. Brooks, DVM, DipABVP
Educational Director, VeterinaryPartner.com
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
The Centers for Disease Control and Prevention monitor leptospirosis
cases in people, and 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 and 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 penicillin
with a fluroquinolone type antibiotic (such as ) 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.
Hemodialysis?
In a recent study from the University of California at Davis (JAVMA,
Vol 216, No3, p271-5) dogs judged as having mild to moderate increases in
renal parameters received traditional fluid therapy and 82% survived. Dogs
having moderate to severe elevations tended to receive hemodialysis. Prognosis
was worse for the severely affected that did not receive hemodialysis, while
86% of those receiving hemodialysis survived. In short, dogs with the most
severe renal toxin build up probably need referral to a critical care facility
that supports hemodialysis.
What Constitutes a Moderate to Severe Toxin Build Up?
The parameters measured in the assessment of kidney function are called
BUN (blood urea nitrogen - with normal levels around 25 mg/dl) and creatinine
(normal levels less than 2.0 mg/dl). In the above study, the group termed
mild to moderate had an initial BUN level ranging from 24 to 225 mg/dl and
initial creatinine levels between 1.7 and 11.5 mg/dl. Again, 82% of these
dogs survived with only traditional fluid therapy as can be performed in
most veterinary practices. The moderate to severe group had initial BUN levels
ranging from 97 to 365 mg/dl and initial creatinine levels ranging from
6.5-21.9 mg/dl. Obviously, there is some overlap.
VACCINATION REACTIONS ARE COMMON!
Vaccination Options
Vaccination against Leptospira interrogans is only available for the
serovars called canicola, grippotyphosa, pomona and icterohaemorragiae.
As a result of long standing use of this vaccine, it is hard to assess how
important it is to vaccinate against leptospirosis. (As you might imagine,
most recent outbreaks involve serovars for which vaccination does not exist.)
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.
Copyright
2007 - 2007 by the Veterinary Information Network, Inc.
All rights reserved.
This work was originally published by Veterinary Information Network,
Inc. (VIN)
and is republished with VIN's permission
Leptospirosis and Your Pet: A CDC Fact Sheet
This fact sheet is designed
to assist pet owners in answering questions related to leptospirosis in
pets and the health risk to humans exposed to Leptospira-infected pets.
What is Leptospirosis?
Leptospirosis is a disease is caused by spiral shaped bacteria called
leptospires. It occurs worldwide and can affect humans as well as many wild
and domestic animals, including dogs and cats. The disease can be serious
for both humans and animals. In people, the symptoms are often like the
flu, but sometimes leptospirosis can develop into a more severe, life-threatening
illness with infections in the kidney, liver, brain, lung, and heart. For
more information on leptospirosis in humans, look at the following site:
Your pet can get leptospirosis too, and although this has not happened
often, the disease has been diagnosed more frequently in the past few
years. The information given here will show you how to protect yourself
and your pets from getting leptospirosis and what to do if your pet does
become infected.
How do People and Animals get Leptospirosis?
The bacteria are spread through the urine of infected animals, which
can get into water or soil and can survive there for weeks to months.
Humans and animals can become infected through contact with this contaminated
urine (or other body fluids, except saliva), water, or soil. The bacteria
can enter the body through skin or mucous membranes (eyes, nose, or mouth),
especially if the skin is broken from a cut or scratch. Drinking contaminated
water can also cause infection. Infected wild and domestic animals may continue
to excrete the bacteria into the environment continuously or every once
in a while for a few months up to several years.
If your pet has become infected, it most likely came into contact with
leptospires in the environment or infected animals. Your pet may have
been drinking, swimming, or walking through contaminated water. Because
of increased building and development into areas that were previously rural,
pets may be exposed to more wildlife, such as raccoons, skunks, squirrels,
opossums, or deer that are infected with leptospirosis. Dogs also may pass
the disease to each other, but this happens very rarely.
What Pet Animals get Leptospirosis?
All animals can potentially become infected with leptospires, although
cases of leptospirosis in cats are rare.
What are the Signs of Leptospirosis in Pets?
The clinical signs of leptospirosis vary and are nonspecific. Sometimes
pets do not have any symptoms. Common clinical signs reported in dogs include
fever, vomiting, abdominal pain, diarrhea, refusal to eat, severe weakness
and depression, stiffness, severe muscle pain, or inability to have puppies.
Generally younger animals are more seriously affected than older animals.
What Should I do if I Think my Pet has Leptospirosis?
Contact your veterinarian immediately. Your veterinarian can perform
tests to detect the presence of leptospiral antibodies or organism in
your pet.
Is there a Treatment for Leptospirosis in Pet Animals?
Yes, leptospirosis is treatable with antibiotics. If an animal is treated
early, it may recover more rapidly and any organ damage may be less severe.
Other treatment methods, such as dialysis and hydration therapy may be
required.
The time between exposure to the bacteria and development of disease
is usually 5 to 14 days, but can be as short as a few days or as long as
30 days or more.
What Should I do if I have been Told my Pet has Leptospirosis?
If your pet has been confirmed by your veterinarian as having leptospirosis,
the appropriate action to take will depend on the nature of contact with
your pet. Normal daily activities with your pet will not put you at high
risk for leptospirosis infection. Types of contacts that are considered
to be high risk include direct or indirect contact with urine, blood, and
tissues of your pet during its infection. Assisting in the delivery of
newborns from an infected animal is also considered a high-risk activity
for transmission of leptospirosis.
If you have had these types of high-risk contacts with your pet during
the time of its infection, inform your physician. If common symptoms,
such as fever, muscle aches, and headaches, occur within 3 weeks after
a high-risk exposure, see your physician. Tests can be performed to see
if you have this disease.
How can I Protect Myself and Other People when my Pet has Leptospirosis?
The risk of getting leptospirosis from a dog in standard instances is
suspected to be low. The primary mode of transmission of leptospirosis
from pets to humans is through direct or indirect contact with contaminated
animal tissues, organs, or urine. Always contact your veterinarian and
your physician if you have concerns about a possible exposure to an infected
animal.
Do not handle or come in contact with urine, blood, or tissues from
your infected pet before it has received proper treatment.
If you need to have contact with animal tissues or urine, wear protective
clothing, such as gloves and boots, especially if you are occupationally
at risk (veterinarians, farm workers, and sewer workers).
As a general rule, always wash your hands after handling your pet or
anything that might have your pet's excrement on it.
If you are cleaning surfaces that may be contaminated or have urine
from an infected pet on them, use an antibacterial cleaning solution or
a solution of 1 part household bleach in 10 parts water.
Make sure that your infected pet takes all of its medicine and follow
up with your veterinarian.
How can I prevent leptospirosis in my pet?
Keep rodent problems (rats, mice, or other animal pests) under control.
Rodents can carry and spread the bacteria.
Get your pet vaccinated against leptospirosis.
The vaccine does not provide 100% protection. This is because there
are many strains (types) of leptospires, and the vaccine does not provide
immunity against all strains. It is important to get your pet vaccinated
again even if it gets leptospirosis because it can still get infected with
a different strain of leptospires.
Copyright
1991 - 2007, Veterinary Information Network, Inc.
This work was originally published by Veterinary Information
Network, Inc. (VIN)
and is republished with VIN's permission.
back to top
****************************
Introduction: The most
common Leptospira serovars infecting dogs were reported to be canicola and
icterohaemorrhagia in older studies, but pomona and grippotyphosa have been
the most common isolated in recent studies. This shift may represent exposure
of pet dogs to infected wildlife such as raccoons and opossums, which inhabit
suburban and urban areas.
Clinical Findings: Dog of all ages may be affected, and there is
no sex predilection. The incubation period is 4-12 days. Nonspecific signs
such as fever, depression, anorexia, and generalized pain may be seen during
this time. Vasculitis, thrombocytopenia, and coagulopathy may develop. Within
a few days, additional signs of uremia such as dehydration, vomiting, and
oral ulceration, are seen. The liver is variably affected, and the degree
of icterus often reflects the severity of the disease. Meningitis, uveitis,
and abortion have been rarely reported.
Hematologic abnormalities include leukocytosis, lymphopenia, monocytosis,
and thrombocytopenia. Serum chemistry may reveal azotemia and electrolyte
disturbances secondary to the renal failure, including hyponatremia, hypochloremia,
and hyperphosphatemia. Serum levels of hepatic enzymes (AST, ALT, alkaline
phosphatase) and serum bilirubin increases if the liver is affected. Urine
sediment usually contains RBC, WBC, and granular casts. Isosthenuria, proteinuria,
and glucosuria reflect tubular damage.
Lesions: In acute disease, the kidneys or liver, or both are swollen.
Hemorrhages may be present in any organ. Other lesions may include any of
those seen with acute uremia. In chronic cases, white or gray foci or streaks
may be seen in the kidney and liver. Histologically, lesions in acute disease
are those of acute uremia, including acute interstitial nephritis and possible
hepatitis. In chronic disease, the only lesions may be chronic interstitial
nephritis or chronic active hepatitis, or both.
Treatment: Renal failure and liver disease are treated with fluid
therapy and other supportive measures to maintain normal fluid, electrolyte,
and acid-base balance. Antibiotic therapy consists of penicillin, tetracycline,
or doxycycline to eliminate leptospiremia, followed by tetracycline or doxycycline
to eliminate the renal carrier phase. Tetracycline should be used with caution
in azotemic animals. The fluoroquinolone antibiotics such as enrofloxacin
also appear to be leptospirocidal.
Prevention/Prophylaxis: To reduce the chances of exposure, owners
are advised to engage in rodent control and keep their dogs leashed. During
epidemics, confinement to the owner's premises should be recommended. Bivalent
bacterins are available and should be administered q6-8mo to maintain a
protective titer for dogs at high risk, e.g., show, stud, or hunting dogs.
If leptospirosis is diagnosed in a kennel, treatment and vaccination of
all dogs in the kennel should be considered. Dogs in contact with wildlife
should receive bacterins containing grippotyphosa and pomona antigens.
**************************
The above information is simply informational.
It's intent is not to replace the advice of a veterinarian nor to assist
you in making a diagnosis of your pet. Please consult with your own veterinarian
for confirmation of any diagnosis. Your pets life may depend on it.