Exam 3 - Leptospirosis

Question 1

T/F: reservoir hosts of leptospira spp. maintain a carrier state in the renal tubules

Answer 1

true

Question 2

how does leptospira spp. enter the body?

Answer 2

penetrate mucosal surfaces or abraded skin

Question 3

how do dogs typically get lepto?

Answer 3

usually through indirect contact with urine of wild animal hosts

Question 4

T/F: any dog from a lepto endemic area, regardless of breed or lifestyle, is at risk of infection

Answer 4

true

Question 5

what are the reservoir hosts that usually serve as the source of lepto infection for incidental hosts such as dogs & humans?

Answer 5

raccoons & rats

Question 6

T/F: immunity against lepto is serogroup specific

Answer 6

true

Question 7

what should be done for a dog living at home with another dog that is infected with lepto?

Answer 7

house mate should be treated empirically with doxycycline or have their titers monitored

Question 8

does vaccine status rule out the possibility of lepto infection?

Answer 8

nope!

Question 9

how are vaccines used to prevent lepto?

Answer 9

can prevent clinical disease & decrease shedding caused by serovars in the vaccine

current vaccines contain serovars icterohaemorrhagiae, canicola, grippotyphosa, & pomona

Question 10

what preventative measures can be taken against leptospirosis infection?

Answer 10

avoid contact with wildlife & standing water

annual vaccination for animals at risk

monitor titers or empirically treat other animals in the home with doxycycline

Question 11

what in-hospital precautions should be taken with a lepto patient? why?

Answer 11

house them in low traffic areas of the hospital that allows for good monitoring, limit their movement & content, clearly label the patient & any samples, walk them in a designated area, minimize urine contamination, at risk humans should contact their health care providers

lepto is considered to be a high risk of transmission to veterinary personnel working with infected dogs, so proper PPE is REQUIRED

Question 12

when do we consider a hospitalized lepto patient to no longer be contagious?

Answer 12

after the patient has been on appropriate antimicrobials for 72 hours - if not properly treated, can shed for months!!!!

Question 13

what is the prognosis for patients with leptospirosis?

Answer 13

survival rate ~80% (generally good with appropriate therapy)

platelets typically improve within 7 days & renal values improve within 10-14 days

Question 14

T/F: in dogs that survive leptospirosis, if they have acute renal tubulointerstitial injury, they may have residual chronic kidney injury

Answer 14

true

Question 15

what are your suitable antibiotic choices when treating suspected leptospirosis empirically when waiting on pending results?

Answer 15

penicillin & doxycycline

Question 16

how long should doxycycline be given to a dog with leptospirosis? why?

Answer 16

2 weeks!!!

need to eliminate organisms from the renal tubules

Question 17

what dosing is used for antibiotics when treating a hospitalized dog for leptospirosis?

Answer 17

ampicillin 20 mg/kg IV every 6 hours in the acute period to treat leptospiremia (can dose reduce if renal dysfunction is present)

can also do 5 mg/kg doxycycline IV every 12 hours

Question 18

why do we not typically do a blood or urine culture when diagnosing leptospirosis?

Answer 18

requires aseptic collection, special media, & incubation for 3-6 months

Question 19

what is important to consider with patient side testing for leptospirosis in regards to anti-leptospiral antibodies?

Answer 19

anti-leptospiral IgM antibodies are detected in the FIRST WEEK OF INFECTION!!!

anti-leptospiral IgG antibodies increase to DETECTABLE LEVELS approximately 2 WEEKS AFTER INFECTION

Question 20

if you run a witness lepto point of care test on an unvaccinated dog with signs of lepto, what is the test detecting? so, what does a positive result mean? what is the disadvantage of this test?

Answer 20

detects IgM

positive result in an unvaccinated dog is consistent with infection

relatively low sensitivity (80%)

Question 21

why may you see a false positive in a witness lepto test on a dog?

Answer 21

dog was vaccinated for lepto within the last 6 months

Question 22

what does a SNAP lepto point of care test detect?

Answer 22

detects antibodies against the LipL32 membrane protein (IgM & IgG))

Question 23

when may you use patient side testing for leptospirosis?

Answer 23

may be used when waiting for results of MAT or PCR

looking for the presence of antibodies

Question 24

how is PCR used to diagnose leptospirosis in dogs?

Answer 24

can diagnose an acute infection - PCR on urine & serum prior to starting antibiotics (blood is ideal in the first 7-10 days, then urine, so submit both)

vaccines won’t cause a false positive! chronic carriers could have a positive urine PCR result

Question 25

does MAT testing reliably predict the infecting serogroup in leptospirosis infections?

Answer 25

nope

Question 26

when do we use microscopic agglutination tests for diagnosing leptospirosis?

Answer 26

acute & convalescent serum titers - usually tests against serovars canicola, icterohemorrhagiae, pomona, grippotyphosa, hardjo, bratislava, & +/- autumnalis

Question 27

how are MAT results interpreted when running titers at acute presentation?

Answer 27

detects anti-leptospiral IgG & IgM via agglutination of live leptospires of a panel of serogroups single titer > 1:800 is considered to be positive in an unvaccinated dog > 1:1600 is considered to be positive in a vaccinated dog

Question 28

what should you do if you have negative MAT results for a dog you suspect an acute infection with lepto? how is this interpreted?

Answer 28

convalescent titers should be performed in 2-4 weeks 4x change is diagnostic for lepto infection!!!!!!

Question 29

why do you need to send the convalescent titers to the same lab for where you send acute titers to for leptospirosis?

Answer 29

considerable inter-lab variability between labs!

Question 30

what is seen on urinalysis of a patient with leptospirosis?

Answer 30

azotemia with inadequately concentrated urine is the hallmark of renal injury!!!! USG may be dilute without azotemia, hyposthenuria is possible (lepto can induce nephrogenic diabetes insipidus) proteinuria, glucosuria, casts, pyuria, & hematuria - indicates renal tubular damage

Question 31

T/F: leptospires are visible by routine light microscopy

Answer 31

false

Question 32

what is seen on a chemistry panel of a patient with leptospirosis?

Answer 32

azotemia - prerenal, renal elevated liver enzymes - especially ALP hyperbilirubinemia secondary electrolyte abnormalities

Question 33

what is seen on CBC of a patient with leptospirosis?

Answer 33

may see an inflammatory leukogram +/- left shift thrombocytopenia is common, but typically mild can be normal

Question 34

what is seen on abdominal ultrasound in a patient with leptospirosis?

Answer 34

changes consistent with acute kidney injury may be seen - hyperechoic renal cortices, renomegaly, peri-renal effusion may see evidence of pancreatitis - enlarged, hyperechoic other non-specific changes - gastric wall thickening, splenomegaly, & mild lymphadenopathy

Question 35

why run a coagulation panel on a suspected lepto patient?

Answer 35

may see elevations in PT/PTT & d-dimers!! coagulopathy risk

Question 36

what does it mean if serum troponin is increased in a suspected lepto patient?

Answer 36

suggests myocardial damage is present

Question 37

T/F: a lepto dog can have disease that is subclinical to peracute

Answer 37

true

Question 38

_____, ________ ________, & _______ ___ ______ are common early signs in animals infected with lepto

Answer 38

fever, muscle tenderness, & reluctance to move

Question 39

how do dogs with leptospirosis often present clinically?

Answer 39

acute kidney failure and/or liver disease

Question 40

why does lepto cause acute kidney injury in dogs? what signs associated with acute kidney injury are seen in lepto dogs?

Answer 40

organisms penetrate & colonize the renal tubular cells - causing interstitial nephritis, renal tubular cell swelling, & vasculitis with decreased GFR pu/pd, oliguria, or anuria lethargy, dehydration, vomiting, abdominal pain

Question 41

why does lepto cause acute liver injury in dogs? what signs associated with acute liver injury are seen in lepto dogs?

Answer 41

lepto causes hepatic necrosis & mild neutrophilic periportal hepatitis lethargy, dehydration, vomiting icterus

Question 42

what signs associated with ocular disease are seen in lepto dogs?

Answer 42

uveitis conjunctivitis

Question 43

why may you see abnormal bleeding in lepto patients? what signs indicate vasculitis?

Answer 43

from vasculitis, DIC, and/or liver dysfunction signs of vasculitis - edema, effusion, petechial hemorrhage, epistaxis, melena, pulmonary hemorrhage, etc

Question 44

what environment does lepto survive best in?

Answer 44

warm, stagnant, or slow moving water

Question 45

does lepto replicate outside of its host?

Answer 45

nope!

Question 46

how long does incubation of lepto last?

Answer 46

variable, but <7 days

Question 47

how long does bacteremia last in an animal with lepto?

Answer 47

up to 10 days

Question 48

what are some possible risk factors for leptospirosis?

Answer 48

exposure to water male dogs herding or working breeds

Question 49

what may be seen on thoracic radiographs of a dog with lepto?

Answer 49

mild interstitial pattern nodular interstitial to alveolar pattern with leptospiral pulmonary hemorrhage syndrome

Question 50

what is included in PPE that should be used when treating dogs with lepto?

Answer 50

gloves, gown, mask/eyewear/face shield wastes are biohazard - label all as lepto suspect!!!

Question 51

what testing is used for detecting anti-leptospira antibodies?

Answer 51

patient side tests MAT

Question 52

what testing is used for detecting lepto organisms?

Answer 52

PCR on blood or urine tissue biopsy dark field microscopy on blood or urine culture using specific media

Question 53

what should you do if you get a negative result on a witness lepto test in a dog that is very suspicious for lepto?

Answer 53

retest them in 3-7 days

Question 54

if a lepto patient isn't clinically dehydrated, but you're starting them on fluids, what do you assume? how long do you take to correct the dehydration?

Answer 54

estimate 5% dehydrated correct it over 4-6 hours

Question 55

when looking at urine output in a patient with an acute kidney injury, what is your target level of production? what value would indicate oliguria?

Answer 55

target is > 2 ml/kg/hr oliguria is < 1 ml/kg/hr

Question 56

what is included in insensible losses? what is the estimate we use for insensible losses?

Answer 56

losses that can't be measured - evaporation, drooling, fecal loss 20 ml/kg/day

Question 57

how do you determine your fluid rate for a patient with an acute kidney injury when considering the 'ins' & 'outs'?

Answer 57

outs - urine output & fluid loss through vomiting/diarrhea insensible losses - 20 ml/kg/day in - matched to outs, iv fluids +/- oral intake fluid rate = urine output + 20 ml/kg/day +/- ongoing losses

Question 58

how do you determine what fluid therapy you need in a patient with a urinary catheter?

Answer 58

rate = (measured urine output/hour) + (20 ml/kg/day) match ins to outs & recalculate every 2-4 hours monitoring urine output/kg/hr each time may need higher fluid rates due to the polyuria

Question 59

T/F: a patient with oliguria/anuria is at high risk of getting volume overload

Answer 59

true

Question 60

what are some signs of volume overload?

Answer 60

moist mucus membranes, gelatinous skin elasticity, serous nasal discharge, chemosis, tachypnea/dyspnea, cough, pleural effusion, SQ edema, & ascites

Question 61

how do you manage oliguria/anuria in a patient with an acute kidney injury?

Answer 61

urine production is < 1 ml/kg/hr & patient is well hydrated administer furosemide or mannitol - no mannitol is patient if over-hydrated target urine production of > 2 ml/kg/hr

Question 62

T/F: in a patient with oliguria/anuria, persistent oliguria or anuria is an indication for dialysis

Answer 62

true

Question 63

what should you do for treatment of AKI if your kidney values plateau?

Answer 63

if the patient feels well - taper fluids while monitoring! if the patient has a poor quality of life due to uremia - look at dialysis or euthanasia

Question 64

what should you do for treatment of AKI if your kidney values become normal?

Answer 64

taper & stop fluids while monitoring kidney values

Question 65

what should you do for treatment of AKI if your kidney values worsen?

Answer 65

dialysis or euthanasia

Question 66

how is tapering fluids done for patients with AKI?

Answer 66

patient needs to feel well & have a stable creatinine taper 25-50% every 12-24 hours (same number of days as diuresis), monitoring their body weight & azotemia outs should decrease as ins are decreased

Question 67

what are some negative prognostic factors associated with leptospirosis?

Answer 67

oliguria/anuria hypocoagulable state albumin is low cardiac involvement

Question 68

are these factors predictive of outcome in a patient with lepto? organs affected, severity of creatinine elevation, DIC, or SIRS

Answer 68

nope!