7. small animal med- lyme disease

what is the causative agent of lyme disease?

borrelia burgdorferi

vector-transmitted by ixodes ticks

when does infection of lyme disease occur after ticks attach to host?

does not infect host until tick is attached for 24 hours

what is the epidemiology of lyme disease?

worldwide distribution

in the US: >90% in northeast, MN and WI

seen in late spring-early summer

what is the lifecycle of ticks and how they transmit lyme disease?

larva/nymphs bite rodents infected with lyme, and then the larva/nymph becomes infected with lyme (at this point, nymphs can transmit lyme to dogs and people)

adult infected ticks bite deer which then infects them with lyme

what 2 species of ticks carry lyme disease in the western united states?

1. ixodes spinipalpus

2. ixodes pacificus

how is lyme disease transmitted in dogs?

local skin infestation followed by generalized infection in:

-connective tissues

-joint capsules

-muscle

-lymph nodes

what is the incubation period of lyme disease?

2-5 months

what is the most common manifestation of lyme disease in dogs?

polyarthritis

how does polyarthritis in dogs infected with lyme present?

chronic, non-erosive arthritis

-often subclinical

-may be septic or immune-mediated (immune complex deposition)

what systemic clinical signs are seen with lyme disease?

anorexia

weight loss

lethargy

lymphadenomegaly

what are characteristics of renal disease associated with lyme disease?

protein losing nephropathy

acute progressive renal failure (lyme nephritidis-high mortality w/o dialysis)

-mostly in labs and goldens

what are other clinical sign manifestations of lyme disease?

lyme myocarditis

CNS inflammation

what clin path changes are seen with lyme disease?

-leukocytosis with left shift, monocytosis, mild anemia

-NO thrombocytopenia (if present--> co-infection)

-proteinuria (glomerular dz)

-azotemia

-neutrophilic inflammation in joints

how is lyme disease diagnosed?

clinical signs and serology

serology alone is not that helpful, as seropositivity is much higher than the incidence of disease

-subclinical infection is common

-documents exposure

what bedside/POC tests are available to test for lyme?

SNAP4DxPlus and VetScan rapid (serology)

what quantitative tests are available to test for lyme?

Quant C6 and Multiplex (serology)

how does the quantitative C6 or OspF tests work?

work as therapy evaluation:

-test pre, 3 and 6 months

-look for decreased antigen load

-gives new baseline for future comparison

ie, tests if there is an active infection and if therapy is warranted for infected animals

what should you do with a positive case of lyme disease?

depends:

-signs?

-lab abnormalities?

-proteinuria?

what are 4 categories of positive animals with lyme disease?

1. asymptomatic, non-proteinuric

2. symptomatic, proteinuric

3. asymptomatic, proteunuric

4. symptomatic, non-proteinuric

what should you do with a positive case of lyme that is asymptomatic and non-proteinuric?

nothing

what should you do with a positive case of lyme that is symptomatic and non-proteinuric?

treat the lyme disease

what should you do with a positive case of lyme that is asymptomatic and proteinuric?

periodic recheck, if persistent or severe proteinuria:

-treat proteinuria

-treat the lyme disease

what should you do with a positive case of lyme that is symptomatic and proteinuric?

treat the lyme dz and treat proteinuria:

-renal friendly diets

-ACE inhibitors

-angiotensin-receptor blockers

what should you do with a positive case of lyme dz with proteinuria, hypoalbuminemia, nephrotic syndrome, or rapidly progressive azotemia?

immunosuppressive agents and antimicrobials

if progressively worse, may need dialysis

what is the therapy for lyme disease?

-doxycycline (10mg/kg q12-24hrs for 28 days)

-amoxicillin

-cefovecin

and supportive therapy

does polyarthritis caused by lyme disease improve?

yes, polyarthritis will improve in 48-72 hours

may have recurrent episodes that respond to antibiotics

what is the prognosis for patients who develop lyme nephritidis?

grave prognosis (use immunosuppressive agents for therapy)

will therapy for lyme dz clear the organism completely?

no- will never eliminate lyme. there is a clinical cure, but there is no microbiologic cure for lyme

how is lyme disease prevented?

-strict tick control

-vaccine (esp in high risk dogs)

what different vaccines are available for lyme disease in dogs?

1. recombinant monovalent (OspA)

2. bivalent whole-cell inactivated (OspA and OspC)

3. chimeric recombinant (OspA and 7 types of OspC)

what is the single protein vaccine (OspA) for lyme disease?

-protects against infection and signs

-OspA antibodies block organism migration to the dog (kills the organism in the tick)

-no effect in the dog

what are dual protein vaccines for lyme disease (OspA and OspC)?

vaccines that prevent infection and have an affect in the dog

what should be considered when vaccinating for lyme disease with single and dual protein vaccines?

-vaccinate high risk dogs before tick season

-gives immunity for at least 6 months

-test to differentiate vaccine from infection