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Basics ⬇

Basics

Definition

  • One of the most common tick-transmitted zoonotic diseases in the world.
  • In man caused by spirochete species of the Borrelia burgdorferi sensu lato complex (e.g., B. burgdorferi sensu stricto, B. afzelii, B. bavariensis, B. garinii, and others).
  • Dominant clinical feature (dogs)-recurrent lameness due to arthritis; sometimes anorexia and depression; may develop renal disease.
  • Reported in humans, dogs, horses, and sporadically in cats.

Pathophysiology

  • Arthritis-caused by the presence of migrating spirochetes in tissue and subsequent cellular and humoral immune responses of the host.
  • Local skin infection after a tick bite is followed weeks to months later by a generalized infection of predominantly connective tissue in joints, tendons, muscles, and lymph nodes.
  • While an erythema migrans (EM) may be observed at the site of Bb inoculation, this lesion is unique to human. The EM is not seen in dogs.
  • Immune complexes with Bb-specific antigens have been demonstrated in dogs and can be deposited in the kidneys; viable Bb organisms are not found in the kidneys.
  • The incubation period in experimentally infected dogs is 2–5 months.

Systems Affected

  • Persisting Bb organisms-found in tissues with a high content of collagen (skin, joints, tendons, pericardium, peritoneum, meninges, muscle, heart, and lymph nodes); rarely found in body fluids (blood, CSF, and synovial fluid).
  • Pathologic changes-with few exceptions restricted to joints, draining lymph nodes; in rare cases involvement of the kidneys.

Genetics

Certain dog breeds are reported to develop severe renal failure (e.g., Bernese mountain dogs, Labrador, Golden retriever).

Incidence/Prevalence

  • Seroprevalence in dogs within a population varies greatly with exposure to infected ticks in endemic areas; in the upper Midwest and northeast of the United States and in central Europe seroprevalence is 2–10%.
  • Clinically apparent LB develops in a fraction of infected individuals; mechanisms unclear; however, co-infections with other organisms (e.g., Anaplasma phagocytophilum) may impact on clinical outcome.

Geographic Distribution

  • Northern hemisphere (North America, Europe, Asia).
  • United States-the majority of cases have been reported in the Mid-Atlantic to New England coastal states, northeastern states, and upper midwestern states. Ecologic conditions supporting LB exist in adjacent states and also on the West Coast.
  • Europe-absent or less frequent in areas bordering to the Mediterranean basin.

Signalment

Species

Dog and rarely cat

Mean Age and Range

Experimentally, young dogs (pups) appear to be more susceptible than adult dogs.

Signs

  • Recurrent lameness due to arthritis.
  • Experimentally, acute form lasts for only 3–4 days; reoccurs days to weeks later in the same or other limbs (shifting lameness); one or more joints may be swollen and warm; a pain response is elicited by palpation; responds well to antibiotic treatment.
  • Affected dogs may refuse to walk or stand or walk stiffly with an arched back and may be sensitive to touch.
  • Chronic non-erosive polyarthritis found in animals with prolonged infection without adequate treatment; may persist despite antimicrobial therapy.
  • Fever, anorexia, and depression may accompany arthritis.
  • Superficial lymph nodes close to the infecting tick bite may be swollen.
  • Kidneys-reported glomerulonephritis with immune-complex deposition in the glomeruli leading to fatal renal disease; patients may present with renal failure (vomiting, diarrhea, anorexia, weight loss, polyuria/polydipsia, peripheral edema or ascites); protein loss (protein-losing nephropathy); hypoalbuminemia.

Causes

  • Bb-transmitted by hard-shelled tick species of the genus Ixodes (e.g., I. scapularis, I. pacificus, I. ricinus, I. persulcatus).
  • Infection-only after a tick (nymph or adult female) has been attached to the host for at least 18 hours.

Ixodes Ticks

  • Have a 2- to 3-year life cycle depending on availability of hosts.
  • Uninfected eggs are deposited in midsummer.
  • Larvae-hatch a few weeks later; become infected by feeding on small mammals or birds that carry Bb organisms.
  • Nymphs-larvae molt into nymphs in the spring of the following year; stay infected or become infected by feeding again on mammals, birds, or lizards.
  • Adults-nymphs molt into adults in summer and stay infected; females mate and feed on larger mammals (e.g. deer); drop off and hide under leaves until the following summer, when they each lay about 2,000 eggs; males usually do not attach and do not feed.

Risk Factors

Canine LB is a peri-domestic disease due to expansion of housing into tick habitat; outdoor activities; roaming in and travel to endemic areas places dogs at risk.

Diagnosis ⬆ ⬇

Diagnosis

Diagnosis of LB is a clinical conclusion made on the basis of compatible clinical signs, response to antibiotic therapy, exclusion of other diagnoses, appropriate laboratory data (particularly antibody testing), and history of exposure to an epidemiologic environment that provides the opportunity for infection with Bb.

Differential Diagnosis

  • Lyme arthritis-differentiate from other inflammatory arthritic disorders.
  • Bacteria-anaplasmosis; ehrlichiosis; Rocky Mountain spotted fever; others.
  • Immune-mediated diseases-idiopathic, lupus erythematosus, rheumatoid arthritis.
  • Specific breed diseases-Akita arthritis, shar-pei fever.
  • Rule-out other disorders with serologic assays and immune testing (antinuclear antibodies; lupus erythematosus preparations).

CBC/Biochemistry/Urinalysis

  • With arthritis only-unremarkable.
  • With protein-losing glomerulopathy-uremia, proteinuria, hypercholesterolemia, hyperphosphatemia, and hypoalbuminemia usually occur.

Other Laboratory Tests

  • Fluid from affected joints-high WBC counts (up to 75,000/µL; up to 97% PMNs).
  • Detection of specific antibodies indicates only exposure to Bb antigens; Western blotting/line immunoassay/fluorescent bead-based multiplex assay allow differentiation between vaccination and infection; cross-reaction with antibodies induced by other bacterial infections is only problematic in tests with lysate antigen preparations.
  • The membrane ELISA in-house test (SNAP 3Dx or 4Dx, IDEXX Labs, Westbrook, ME) detects a subgroup of antibodies against the outer surface protein VlsE of Bb using the C6 peptide; convenient test that only indicates infection and does not respond to vaccine-induced antibodies-C6-specific antibodies normally drop or may even disappear approximately 4–6 months after antibiotic therapy. Low to moderate pre-therapy levels do not drop significantly.

Imaging

Radiographs-help identify effusions in the joint; may help distinguish erosive from non-erosive joint disease; rule out trauma.

Diagnostic Procedures

  • Organisms can be demonstrated regularly in tissue samples taken from skin or synovium after experimental infections with PCR or culture; however, under field conditions these tests are time-consuming and unreliable (not recommended).
  • Blood samples particularly are typically negative when tested with PCR or culture.

Pathologic Findings

Gross

  • Swollen joints with excess synovial fluid.
  • Sometimes enlarged lymph nodes.

Histopathology

  • Acute, clinically apparent arthritis-fibrinopurulent synovitis.
  • Other joints-may have mild synovitis with infiltration of lymphocytes and plasma cells.
  • Lymph nodes-may show cortical hyperplasia with multiple enlarged follicles and expanded parafollicular areas.
  • Skin near tick bite site-shows perivascular infiltrates of plasma cells, lymphocytes, and some mast cells in the superficial dermis.
  • Renal lesions-glomerulonephritis, diffuse tubular necrosis with regeneration, and interstitial inflammation.

Treatment ⬆ ⬇

Treatment

Appropriate Health Care

Outpatient

Nursing Care

Keep patient warm and dry.

Activity

Reduced activity until clinical signs improve.

Diet

No change needed

Client Education

  • Inform client of importance of regular application of antibiotics as prescribed.
  • A case of diagnosed canine LB should prompt a discussion of the risk to humans living in the same area as the dog.

Surgical Considerations

Aspiration of synovial fluid-may be considered for diagnostic purposes.

Medications ⬆ ⬇

Medications

Drug(s) Of Choice

  • Most commonly used antibiotics-doxycycline (5–10 mg/kg PO q12h; with food; vomiting and gastritis possible), amoxicillin (20 mg/kg PO q8–12h) or azithromycin (25 mg/kg PO q24h).
  • Doxycycline-preferred when a co-infection with Anaplasma phagocytophilum occurs.
  • Antibiotics-do not terminate the infection completely; consequently, persistent infection with a very low bacterial burden remains; treatment significantly improves clinical signs and pathology.
  • Recommended treatment period-4 weeks.

Contraindications

Consider potential side effects of applied drugs.

Precautions

Doxycycline can be used in young (<6 months old) animals.

Alternative Drug(s)

  • Corticosteroids-may initially ameliorate signs; mask effects of antibiotics for diagnostic purposes; enhance clinical signs later by immunosuppression.
  • Nonsteroidal pain medications-use judiciously to avoid masking signs.

Follow-Up ⬆ ⬇

Follow-Up

Patient Monitoring

  • Improvement-in acute Lyme arthritis seen within 2–5 days of antibiotic treatment.
  • If no improvement or if signs exacerbate-consider a differential diagnosis.

Prevention/Avoidance

  • Mechanical removal of ticks-groom animals daily.
  • Prevention of tick attachment-acaricides and repellents (do not use permethrin on cats) supplied as spot-on, sprays, collars or pills/chewables.
  • Vaccines-all vaccines currently available depend predominately on the effect of antibodies against the spirochetes' outer surface protein A (OspA). These antibodies prevent the spirochetes' migration within the feeding tick from the gut into the salivary glands. Commercially available vaccines for dogs contain non-adjuvanted recombinant OspA or OspA and numerous antigens (e.g. OspC) in adjuvans (bacterins) produced from inactivated cultured Bb organisms. Studies have shown that the protection rate improves over time due to booster immunizations that induce higher and longer-lasting vaccine antibody titers.
  • Tick population control in the environment-restricted to small areas; limited success by reducing deer and/or rodent population.

Possible Complications

Fatal renal failure

Expected Course and Prognosis

  • Recovery from acute lameness expected 2–5 days after initiation of antibiotic treatment.
  • Disease may be recurrent with intervals of weeks to months; responds again to antibiotic treatment.

Miscellaneous ⬆

Miscellaneous

Age-Related Factors

  • Young pups appear to be more susceptible than adult dogs under experimental conditions.
  • Disease can occur in dogs of all ages.

Zoonotic Potential

  • Occurs in humans; source of infection is infected ticks.
  • Dogs can transport unattached ticks, which later attach to humans-however, Ixodid are not intermittent feeders; once tick starts feeding on a dog, it usually feeds to repletion and does not change hosts.
  • LB cannot be transmitted directly from dogs to humans.

Pregnancy/Fertility/Breeding

  • Although possible, there is no convincing evidence that Bb infection is transmitted in utero in dogs.
  • Pregnant animals tolerate antibiotic treatment; do not use tetracyclines.
  • Maternal C6-specific antibodies can be passed from dams to puppies.

Synonyms

  • Lyme arthritis
  • Lyme disease

Abbreviations

  • Bb = Borrelia burgdorferi
  • CSF = cerebrospinal fluid
  • ELISA = enzyme-linked immunosorbent assay
  • IFAT = immunofluorescence antibody test
  • LB = Lyme borreliosis
  • PCR = polymerase chain reaction
  • PMN = polymorphonuclear neutrophil
  • WBC = white blood cell

Internet Resources

Author Reinhard K. Straubinger

Consulting Editor Stephen C. Barr

Client Education Handout Available Online

Suggested Reading

Greene CE, Straubinger RK, Levy SA. Borreliosis. In: Greene CE, ed., Infectious Diseases of the Dog and Cat, 4th ed. St. Louis, MO: Saunders Elsevier, 2012, pp. 447–465.

IRIS Glomerular Disease Study Group. Consensus recommendations for treatment for dogs with serology positive glomerular disease. J Vet Intern Med 2013, 27Suppl 1;60–66.

Krupka I, Knauer J, Lorentzen L, et al. Borrelia burgdorferi sensu lato species in Europe induce diverse immune responses against C6 peptides in infected mice. Clin Vaccine Immunol 2009, 16:1546–1562.

Straubinger RK, Straubinger AF, Summers BA, et al. Status of Borrelia burgdorferi infection after antibiotic treatment and the effects of corticosteroids: An experimental study. J Infect Dis 2000, 181:1069–1081.

Töpfer KH, Straubinger RK. Characterization of the humoral immune response in dogs after vaccination against the Lyme borreliosis agent: A study with five commercial vaccines using two different vaccination schedules. Vaccine 2007, 25:314–326.