Your Pet and Lyme Disease
This
information is not meant to be a substitute for veterinary care. Always follow
the instructions provided by your veterinarian.
What is Lyme disease?
Lyme disease is caused by the corkscrew-shaped bacteria, Borrelia
burgdorferi which is also called a spirochete. The bacteria are carried by ticks which transmit the
infection when they feed on animals and humans. The disease can cause
generalized illness in animals and humans worldwide.
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In the United States, Lyme disease occurs predominantly on the Pacific coast and in the Midwest, and Atlantic coast states. Regions in which the disease occurs commonly are called endemic regions. About 75% of dogs living in endemic regions are exposed to infected ticks, but only a small percentage of exposed dogs develop signs of disease. |
Lyme disease was first described in 1975 when an unusual outbreak of
rheumatoid arthritis occurring in children was reported in Lyme, Connecticut. In 1982,
the bacteria Borrelia burgdorferi was determined to be the cause of
that outbreak. Since Lyme disease was first described in the early 1980's,
the frequency of occurrence of disease has increased twenty-five fold. Today, Lyme disease is
the most common vector-borne (transmitted by insects or arthropods) disease
occurring in people and probably in dogs in the United States. Dogs are most frequently infected with the Lyme disease bacteria,
but infections can also occur in horses, cattle, and cats.
How is Lyme disease transmitted?
The bacteria live in mice, deer and other small mammals. The type of ticks that
can transmit the bacteria from these wildlife to humans and domestic
animals are the
Ixodes ticks. The bacteria replicate
(increase in number) in the wildlife without causing them to become
sick. When a tick feeds on the infected wildlife the tick picks up the
bacteria, then they transmit the bacteria to another animal the next time
they feed.
If your pet is diagnosed with Lyme disease you are not at risk of
getting Lyme disease directly from your pet. The bacteria increase to high
levels in the blood of wildlife whereas humans and domestic animals develop very low levels of the
bacteria in their blood and these low levels will not infect a feeding
tick. Researchers have learned that infected ticks must feed for
about 24 hours to transmit the bacteria to a susceptible animal so quick
removal of ticks from your pet reduces the chance of infection.
Clinical signs
The most common sign of Lyme disease in dogs is arthritis, which causes sudden lameness,
pain ands sometimes swelling in one or more joints. Other signs that
may be seen include fever, lack of appetite, dehydration, inactivity, and swollen lymph nodes. In
severe cases, the infection can cause kidney failure and death although
this does not occur commonly in dogs. The signs of heart and nervous
system dysfunction seen in infected humans are not often seen in animals.
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Humans often show a skin rash that looks like a target but this is rarely seen in infected dogs. |
Diagnosis
A diagnosis of Lyme disease is usually made based upon a history of
being in an endemic area, signs of arthritis and favorable response to
treatment. There is a blood test that measures antibodies to the bacteria
but many dogs that live in endemic regions will have a positive blood
test. A positive blood test just means that the dog was exposed to Borrelia burgdorferi
but not all dogs that are exposed will show signs of disease. Early
in the disease dogs may not yet have a positive blood test. Dogs that have
been vaccinated for Lyme disease may have a positive blood test depending
upon the type of blood test that is performed. There are several other
causes of arthritis that occur in dogs that must also be considered.
Treatment
Borrelia burgdorferi is easily treated with antibiotics.
The signs of Lyme disease usually regress rapidly in response to
treatment. If the disease remains untreated the disease becomes chronic
and can cause kidney damage although dogs are much less likely to develop
chronic disease than are people.
Prevention
Animals in endemic areas are at greatest risk for infection. The best method of prevention is to avoid tick infested areas, especially in the spring when the young ticks are most active. When returning from
a tick-infested area do a thorough search for ticks on both yourself and your animals.
Ticks should be removed carefully with a tweezers, pinching the tick near the point
they enter the skin. There are also many highly effective veterinary products that will kill ticks on your dog before
the tick can transmit the bacteria. Remember that early removal of
ticks reduces the chance that the tick will transmit Lyme disease.
There is a vaccine approved for use in dogs for Lyme disease
prevention. Most authors of veterinary articles on Lyme disease do not recommend
vaccinating dogs in non-endemic areas. Not all authors agree on
how effective the vaccine is in preventing Lyme disease and not all
authors agree that the vaccine should be given in endemic regions. The
vaccine can cause some blood tests for Lyme disease to become positive. For more information about tick control products or Lyme disease, consult your veterinarian.
References:
For additional information on Lyme disease see: the
Centers for Disease Control
(CDC) website
This topic was written by Wendy Harless, Oregon State University, class of
2002 with the guidance of Dr.Diana Stone, Washington State University.
Washington State University assumes no liability for injury to
you or your pet incurred by following these descriptions or procedures.
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Last Edited: Dec 21, 2007 3:17 PM
