(Submitted by Lynn Duckett and the USKBTC H&G Committee.)
1) What is Lyme Disease?
2) What symptoms will the dog exhibit?
- Lyme Disease is a bacterial infection caused by spirochete
bacteria known as Borrelia burgdorferi. Because Lyme Disease
is relatively new in dogs, there are still some facts experts
are unsure about, including how to interpret test results and
how to treat the affected dogs. According to the CDC, Lyme
disease is the most commonly reported vector-borne disease in
the United States. Also, there has been a trend of increasing
incidence in endemic areas as well as geographic spread to new
areas over the last few years. Lyme Disease can affect any
- When Borrelia burgdorferi organisms enter the mammalian
host via a tick bite, the spirochetes initiate an infection
that develops slowly over weeks and months. Periods with no
obvious illness alternate with periods during which the
patient shows mild to severe clinical signs. During this same
time, the organisms establish a persistent infection that the
immune system is unable to eliminate. As a result, the
veterinarian is often confronted with two canine patient
populations. The “classic” Lyme disease patient presents with
mild to severe signs of the disease. On the other hand, many
apparently healthy and asymptomatic animals are brought in for
other reasons and the infections are discovered accidentally
when the veterinarian screens for possible infections. It is
reasonable to wonder if an individual dog’s stoicism may
effectively mask the clinical signs brought on by Lyme
disease, particularly in breeds of dogs known for stoicism,
(i.e. the Kerry Blue Terrier).
- Clinical signs develop in only about ten percent of
infected dogs, meaning a dog can test positive for Lyme and
remain asymptomatic! When they do occur (usually two to five
months after the tick bite), the most common documented
symptom is lameness (due to polyarthritis, followed by
enlarged lymph nodes (lymphadenopathy), anorexia, lethargy and
fever. Less common syndromes associated with Lyme disease
include renal disease (Lyme nephritis), heart disease
(myocarditis) and neurological disease. Since our dogs cannot
verbally describe their symptoms, it is not known whether or
not dogs get the devastating recurrent disease syndromes
typical of humans infected with Lyme.
- Statistically, roughly ninety percent of cases of canine
patients with Lyme disease present to the veterinarian with
signs of limping (usually only one leg), accompanied by lymph
node swelling in the affected limb and temperature of 103
degrees. Under experimental conditions, dogs become
intermittently lame due to a severe inflammatory response in
the synovial membrane of the joint closest to the tick bite.
The limping usually progresses over three to four days from
mild to complete disuse of the painful leg. Once the bacteria
has spread in the dog’s body, it can progress within two to
three days from mild discomfort in one limb to the point where
the dog is in such muscle and joint pain it will refuse to
move. It is important to note that the “bull’s eye” rash or
erythema migrans, which is typical in the human patient is not
commonly found in canine patients. Also important to note is
that prompt diagnosis and treatment with antibiotics can cure
the dog before permanent joint or nerve damage occurs.
- Lyme disease should always be suspected when a dog ran or
played normally a few days ago, has had no trauma or previous
arthritic symptoms and suddenly displays lameness with swollen
lymph nodes. However, just as in human medicine, Lyme disease
is called “The Great Imitator” because it has often been
mistakenly diagnosed when another disorder is present, such as
an autoimmune disease, lymph tissue cancer, Blastomycosis or
septicemia. Therefore, it is imperative that the vet rule out
other possible causes of the dog’s symptoms while continuing
to consider Lyme as the possible culprit.
3)How prevalent is Lyme Disease in dogs?
- Lyme Disease has been reported in forty-eight states with
the Northeastern and Midwestern states accounting for the
majority of cases. Only ten percent of dogs infected with Lyme
Borrelia burgdorferi develop clinical signs of disease. Up to
seventy percent of dogs that live in the northeastern and
midwestern states in the U.S. have serum antibodies to Lyme
Disease. Statistically, fifty percent of dogs in the northeast
and Midwest are infected annually.
4) How do dogs get Lyme Disease?
- Dogs are infected with Borrelia burgdorferi bacterium when
bitten by an infected tick. At least three known species of
ticks can transmit Lyme Disease. However, the most common one
responsible for transmitting the disease is the Ixodes
Scapularis tick, commonly known as the Black-Legged or Deer
tick. These ticks are much smaller than the common dog
tick-about the size of a poppy seed. The picture below
demonstrates the size differences between the Deer tick and
the common dog tick, with a pencil used for size
Dog ticks and black-legged ticks compared to a
A. Engorged female
H. Engorged female
- Not all Black-Legged ticks harbor these bacteria. In areas
of the northeastern and midwestern states, where Lyme disease
is most prevalent, only twenty-five to fifty percent of ticks
were infected with Borrelia burgdorferi. However, since the
only way to be sure which ticks are infected is to have them
analyzed in a lab, the safest thing is to consider all ticks
as potentially infected.
- At the time of the tick bite, the spirochete bacteria
reside in the tick’s gut. Stimulated by the blood meal, the
spirochetes begin to migrate to the tick’s salivary glands.
The bacteria are then injected into the dog with the saliva
from the tick as it feeds on the dog’s blood. Studies have
shown that it takes twelve to twenty-four hours for the
organisms to transfer from the tick’s mid -gut to the host. If
the tick is removed before it has been attached for that long,
it cannot transmit the bacteria to the dog.
5) How is Lyme disease diagnosed?
- With the recent advance of a reliable in-hospital test
kit, the popular “blue-dot” or “snap” test offers results
quickly and inexpensively. The SNAP 3DX test (IDEXX
laboratories, Portland, ME) for example, detects antibodies
within 35 days of tick exposure and remains elevated for an
additional 530 days. This test is reported to have a
sensitivity of 92% and a specificity of 100%. This test shows
infection but does not verify disease.
- The definitive way to diagnose infections is through
culture of the bacteria, usually via skin biopsy samples taken
close to the site of tick attachment. Spirochetal organisms
are rarely detected in blood samples.
- Polymerase chain reaction (PCR) testing has been found to
be more specific and less labor intensive than culturing of
tissue samples. However, negative PCR results do not exclude
an infection because the very few DNA copies of the organisms
are often not numerous enough to be detected in all
- Therefore, four criteria are generally considered
important in establishing the diagnosis of Lyme
- History of exposure to ticks (typically in an area where
Lyme is endemic-although this theory is changing now that Lyme
has been reported in forty-eight states!)
- Typical clinical signs of Lyme borreliosis—arthritis in
one or more joints, characterized by pain, swelling and
- Positive Lyme serology (specific antibodies against
Borrelia burgdorferi are found in the dog’s blood)
- A prompt response to antibiotic therapy
6) How is Lyme disease treated?
- Antibiotics such as the tetracyclines, penicillins and
macrolides are very effective in improving the clinical
symptoms for the patient but usually fail to totally eliminate
the infection. Antibiotics must be given for four weeks.
Corticosteroids (i.e. prednisone) should be used only
cautiously and always in combination with
7) How can Lyme disease be prevented?
- Lyme disease can be prevented by the elimination of ticks
from the environment, removing ticks from the dog within
twelve to twenty-four hours of attachment, by using chemicals
on the dog to repel or kill the ticks when they try to attach
or by vaccination.
8) How can ticks be eliminated from the
- To answer this question, one must understand the life
cycle of the tick. The tick’s life cycle includes four stages;
the egg, larvae, nymph and the adult. This life cycle requires
two years to complete.
- Adult ticks lay their eggs in late summer or early fall,
typically depositing them in a heavy layer of leaves or other
- Larval ticks hatch in early spring and attach themselves
onto tiny rodents, typically the vole or white-footed mouse
(which also tends to live in the heavily mulched areas). The
larval ticks ingest the Borrelia burgdorferi bacteria while
feeding on these tiny rodents, who harbor the bacteria in
- In late spring, the larvae mature into the six-legged
nymph ticks. It is during this stage of the tick’s life
(usually May through August) that it is most likely to
transmit the bacteria to any available mammal, including the
dog. It is important to note that at this stage, the nymphal
tick is much smaller than the head of a straight pin, so is
very hard to see with the naked eye. Since the tick’s presence
on the dog and even its bite cause no pain or itching, it
often remains attached there, undetected, long enough to
complete its blood-meal before it drops off days later to
mature into the next stage.
- In summer, the nymphal tick matures into the adult, which
will lay its eggs later in the summer, starting the cycle all
- So, to eliminate the ticks, we must first eliminate the
small rodents they feed on. This can be accomplished by
clearing out all mulch in the late summer and early fall. This
would break the life cycle at the larval stage, thus
preventing the ticks from establishing themselves on your
- To break the cycle at the nymph and/or adult stage, there
are safe and effective insecticides that can be used in the
dog’s usual environment. In addition, there are several
chemicals that can be used on the dogs to kill or repel the
ticks before they get the chance to inject the bacteria into
the dog. It is important to note that these agents will kill
the tick only after it is on the dog. The longer the tick is
attached and biting, the greater the risk of transmission of
bacteria IF the tick is actually harboring the bacteria in its
gut. Also, no repellent can be expected to keep every single
tick off a dog! One word of caution; more is not always
better…if you’re using a topical spot-on treatment, check with
your veterinarian before also applying a spray, dip, shampoo
- Frontline Plus is available as a liquid spot-on
application or as a spray .It is applied to the dog’s skin and
spreads through the skin’s oil layer. K9Advantix is another
prescription anti-tick medication that also repels mosquitoes
and fleas. Sprays, shampoos, collars, powders and dips are
often also used (in these ingredients, it seems that
permethrin is more effective than pyrethrin). Some vets feel
that tick collars containing the product Amitraz work
- For more information on pesticides, check with the
Environmental Protection Agency (www.epa.gov).
9) How can the tick population be kept to a minimum on the
dog without the use of pesticides?
- Examine the dog after any outdoor excursions and carefully
pick off any ticks you find, using small tweezers to grasp the
tick as close to the dog’s skin as possible and gently pull
away from the skin. Be careful not to crush the tick. After
removal, cleanse the skin with antiseptic.
- Avoid fields of high grass and weeds as much as possible,
especially during late spring through early fall while the
ticks are searching for their blood meals.
- Remember that it takes the bacteria twelve to twenty-four
hours to migrate from the tick’s gut to its saliva and into
the dog. Any tick removed before it’s been attached for that
length of time cannot infect your dog, even if it is carrying
the Borrelia burgdorferi bacteria!
10) What about vaccines?
- Currently, two types of vaccines are available to
veterinarians. Both types of vaccine produce antibodies that
attack the bacteria in the tick and block its transmission to
- The first group of vaccines is more accurately called
“bacterins”. Bacterins are produced from bacteria grown in
cultures that are then chemically or physically inactivated.
The second group of vaccines available relies on recombinant
OspA. (OspA stands for “outer surface protein A) This is a
lipoprotein expressed by the bacteria when the tick is feeding
on a mammal. When the vaccine-initiated antibodies to the OspA
are produced by the dog, these antibodies bind to the surface
of the bacteria in the gut of the tick, thus preventing the
bacteria from migrating to the saliva glands of the tick.
Therefore, the bacteria are “stuck” in the gut of the tick and
cannot infect the dog. Unfortunately, antibody levels of both
vaccines tend to peak shortly and drop off during the
following months, so yearly vaccination for Lyme disease is
recommended by many vets in endemic areas of the
- As with all vaccine types, antibody production is
dependent on the individual’s immune system’s ability to
launch a response to the antigens.
- Lyme Disease or Lyme confusion by Andrew Eschner, DVM,
Senior Field Manager, Veterinary Medical Affairs, Merial
- What is Lyme Disease in Dogs by T.J. Dunn, Jr. DVM
- Lyme Disease: An Investigative Look at Testing, Treatment
and Vaccination by Reinhard K Straubinger
- Ability of Fipronil to Prevent Transmission of Borrelia
burgdorferi , the causative agent of Lyme Disease to dogs by
Richard Jacobson, John McCall, James HunterIII, Roberto Alva,
Jennifer Irwin, Andrew Eschner, Phillipe Jeannin, and Albert
- Efficacy of Nonadjuvanted Outer Surface Protein A
Recombinant Vaccine in Dogs After Challenge by Ticks Naturally
Infected with Borrelia burgdorferi by Jennifer A. Rice Conlon,
Thomas N. Mather, Patrick Tanner, Guillermo Gallo and Richard
- Canine Nonadjuvanted Outer Surface Protein A Monovalent
Lyme Vaccine: Safety with One-Year Duration of Immunity by
- Lyme Disease: Managing a Mysterious Malady by Jeff
- Centers for Disease Control
Last Updated: 11/10/2007, 3:33 pm