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SAM > Cardiovascular - Heartworm > Flashcards

Cardiovascular - Heartworm Flashcards

1
Q

Heart worm species

A

Dirofilaria immitis

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2
Q

Life span of heart worm in dogs

A

6-7m, 184-210d

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3
Q

Life cycle of HW in dogs dependent on

A

ambient temperature ad Wolbachia

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4
Q

Life cycle of HW in dogs

A

adult worms live in PA
after mating female worms release microfilaria (mf) into circulation
mf ingested by female mosquitos - become L1
2 melts over 8-17d period to L3
L3 transmitted from mosquito to dog
L3 to L4 in Sc tissue over 1-12d, then final molt to immature adult (S5)
S5 migrates to vasculature then to PA to complete maturation

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5
Q

T/F: prevalence of HW disease in dogs is increasing

A

true

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6
Q

heart worm infection = heart worm disease?

A

no, heart worm disease occurs when heart worm infection is prolonged or severe

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7
Q

Features of heart worm disease in dogs

A

pulmonary artery and pulmonary parenchyma injury, pulmonary hypertension, R sided cardiac dysfunction, glomerulonephritis, anemia, thrombocytopenia, canal syndrome, DIC

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8
Q

What is considered the onset of heart worm disease in dogs?

A

damage to the pulmonary artery

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9
Q

What occurs in the pulmonary aa in dogs as a result of adult worms living there?

A

inflammation, endothelial damage, myointimal proliferation, disruption of vascular integrity, fibrosis, pulmonary hypertension

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10
Q

Living worms in dogs can create

A

mechanical obstruction within the pulmonary arteries

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11
Q

Dead worms in dogs induce

A

thrombosis and inflammation

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12
Q

Outcome of pathophysiology of HWD in dogs

A

decreased return to left artery and ventricle (preload) = low systemic pressure

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13
Q

What type of hypertrophy occurs in right ventricle in dogs?

A

concentric

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14
Q

2 things that result in increased pulmonary vascular resistance in dogs

A

structural changes causing narrowed pulmonary lumen

vasoactive substance from worms, endothelium, and platelets cause vasoconstriction

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15
Q

What sided heart failure may you see as a result of HW disease in dogs

A

right sided CHF

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16
Q

Which is FALSE regarding pulmonary parenchymal disease resulting from HWD?
A) decreased vascular permeability into surrounding tissue
B) eosinophilic granulomatosis as result from host response
C) pulmonary thromboembolism (PTE) seen
D) post PTE lung consolidation

A

A - increased vascular permeability to tissue (fluids, cells, toxins)

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17
Q

Wolbachia pipientis

A

intracellular, gram -, live in D. immitis
endotoxins and surface proteins have been implicated in pathogenesis and adverse reactions associated wth HWD
Doxy effective attracting Wolbachia

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18
Q

T/F: doxycycline is effective at reducing/eliminating wolbachia and reduces larval and adult stages of D. immitis in dogs

A

true

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19
Q

Heartworm disease and glomerulonephtitis in dogs

A

secondary to antigen-antibody deposition, results in albuminuria (and potentially hypoalbuminemia)

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20
Q

What is caval syndrome in dogs?

A

mechanical obstruction by worms of blood flow to R side of heart and vena cava, only occurs if worm burden is heavy
hemolytic anemia and cariogenic shock result (rare but lifethreatning)

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21
Q

T/F: aberrant migration of worms to other tissues (neuro, muscular, ocular, systemic aa.) more common in dogs than cats

A

false, more common in cats

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22
Q

Clinical signs of HWD in dogs

A

most dogs asymptomatic
exercise intolerance, weight loss, lethargy, cough, tachypnea, dyspnea, hemoptysis, abdominal distension, syncope or collapse, hematuria

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23
Q

PE findings on HWD dog

A 
may be normal
weight loss and poor BCS
split S2
murmur due to tricuspid regurgitation (right apical systolic)
gallop
abnormal lung sounds
tachypnea, dyspnea
R sided CHF
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24
Q

T/F: thoracic rads are helpful to diagnose HWDin dogs

A

True! Look for large, dilated, tortuous pulmonary aa
look at lung parenchyma for interstitial infiltrates
look for R sided cardiac enlargement

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25
Q

CBC abnormalities associated with HWDin dogs

A

neutrophilic, eosinophilia, basophilia, anemia, thrombocytopenia

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26
Q

Why may you see elevated liver enzymes in a HWD dog?

A

hepatic congestion from R sided CHF

27
Q

urinalysis of a dog w HWD may reveal

A

albuminuria

28
Q

When is an echo indicated in a HW patient?

A

if there is concern for pulmonary hypertension and/or canal syndrome

29
Q

What is the test of choice if an arrhythmia is ausculted on a HWD patient (dogs)?

A

echo

30
Q

Best treatment for HWD in dogs?

A

macrocyclic lactone preventative
Doxycycline
Exercise restriction
adulticide therapy with melarsomine dihydrochloride

31
Q

Macrocyclic lactone preventative in dogs

A 
prevents further infection
reduces or eliminates microfilaria
destroys developing L3 and L4
started day HWI is diagnosed
ivermectin, salamectin, moxidectin
32
Q 
Which would you NOT give to a microfilaremic dog? Why?
A) ivermectin
B) Milbemycin
C) Moxidectin
D) Selamectin
A

B - milbemycin

is a potent microfilaricide, death of too many worms at once can cause anaphylaxis

33
Q

Two uses of doxycycline in dogs

A

reduce/eliminate Wolbachia

reduce Mf and other stages of D. immitis

34
Q

Why is exercise restriction imperative in HWD dogs?

A

reduce risk of thromboembolic complications

35
Q

3 dose “split dose” protocol in dogs

A

highly effective at eliminating adult worms
reduces risk of post-adulticidal complications
use melarsomine dihydrochloride, organic arsenical rapidly absorbed after IM injection
dogs with intra-cardiac worms/caval syndrome should not be treated with adulticide until worms. have been extracted

36
Q

“slow kill” of adults with macrocyclic lactones in dogs

A

ongoing damage to pulmonary artery and lungs

method not recommended, could be used for a patient in which 3 dose with melarsomine is not an option

37
Q

Adulticide drug of choice in canines with HWD

A

melarsomine dihydrochloride

38
Q

Adjunct Tx for canines

A

analgesia for melarsomine injections (opioids, corticosteroids or NSAIDs)
corticosteroid therapy - prevent/tx adverse reactions to microfilaricides

39
Q

What could you give a dog to treat pneumonitis, pulmonary granulomas, and pulmonary thromboembolism associated with HWD?

A

corticosteroids

40
Q

Treatment of anaphylaxis associated with microfilaricidal therapy in dogs

A

uncommon except with milbemycin oxide
monitor dogs after preventative
consider pretreatment with corticosteroid and diphenhydramine
avoid milbemycin

41
Q

Treatment of eiosinophilic pneumonitis or granulomatosis in dogs

A

corticosteroids (prednisone or prednisoloe)

often occurs early in disease course

42
Q

treatment of pulmonary thrombosis or thromboembolism in dogs

A

supplemental O2, corticosteroid therapy, sildenafil if pulmonary hypertension severe
can cause sudden death

43
Q

Treatment of pulmonary hypertension in dogs

A

sildenafil, supplemental O2

44
Q

Treatment of congestive heart failure in dogs

A

(R sided)
- furosemide, sildenafil +/- pimobendan, ACE inhibitor if not hypotensive or dehydrated
abdominocentesis if ascites
delay adulticide therapy until CHF stabilized

45
Q

Treatment of caval syndrome in dogs?

A

emergency worm extraction via jugular vein

delay adulticide therapy (at least 30 days)

46
Q

Prognosis for dogs with HWD

A

good with asymptomatic infection
good in dogs w/ mild-moderate disease
guarded for severe HWD
Patients that develop CS, DIC, CHF, PTE, eosinophilic granulomatosis, PA disease = worse prognosis

47
Q

prevention of HWD?

A

educate clients

48
Q

T/F: cats are more resistant to heart worm infections than dogs

A

True, cats are unnatural host

49
Q

T/F: aberrant migration of worms more common in cats

A

True

50
Q

T/F: pulmonary disease can develop in cats even if mature adult worms never exist

A

true

51
Q

Key differences of HWD in cats

A

not preferred target for mosquito
mosquito must have fed on infected dog first
unnatural host - resistant to HWI (no or few adults, often amicrofilaremic)
longer life cycle (7-8m)
aberrant migration more common
mature adults not needed for pulmonary disease to develop

52
Q

If prevalence of HWI low in cats, why is it important we protect cats from D. immitis?

A

cats get HARD

53
Q

What is HARD

A

Heartworm-associated respiratory disease

54
Q

General info about HARD

A

inflammatory and proliferative disease of pulmonary aa, bronchioles and pulmonary parenchyma in cats without mature infections

55
Q

Which is FALSE regarding HARD?
A) ~50% cats with immature infections develop HARD
B) HARD produces asthma like symptoms
C) HARD is a diagnosis of exclusion
D) HARD requires cats to have mature infections

A

D - HARD occurs in cats without mature infections

56
Q

Role of PIMs in HARD?

A

pulmonary intravascular macrophages contribute to profound inflammatory reaction to immature and dead worms

57
Q

Signalment of cats with HARD

A

male, 4-6y, exposure to outdoors

58
Q

Acute signs of HARD

A

due to dead worm embolization
anaphylaxis, resp distress, dyspnea, coughing, shock, ptylism, vomiting and diarrhea, altered mentation, ataxia, vision loss, seizure, sudden death

59
Q

Chronic signs of HARD

A

coughing, wheezing, dyspnea, lethargy, hyporexia, weight loss, exercise intolerance, vomiting, R sided CHF

60
Q

PE on a HARD cat

A

may be normal

abnormal lung sounds, tachypnea/dyspnea, murmur, gallop, weight loss, ascites

61
Q

Why is antigen test not ideal diagnostic for cat HWI?

A

because the antigen detected is in reproductive tract of adult female which is likely not in the cat

62
Q

What diagnostic test is ideal to test cats for HWI?

A

antibody test

63
Q

Treatment of HWI in cats

A

microfilaricidal not indicated because low #sadulticide therapy not recommended - high risk of mortality and morbidity
cats should receive short term corticosteroid therapy for HARD
supplemental O2, parenteral corticosteroid and bronchodilator if embolic/anaphylactic emergency
consider doxy for wolbachia and clopidogrel for PTE prevention

SAM (48 decks)

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