Lecture 8 - Heartworms

Question 1

what are the hosts of heartworm

Answer 1

dogs, ferrets, sea lions, cats

Question 2

T/F: more damage can occur to cats with heartworm infections because they are not a “good” host

Answer 2

TRUE

Question 3

T/F: dogs older than 6 months old are susceptible to heartworm

Answer 3

FALSE - any age is susceptible

Question 4

where do adult worms live

Answer 4

pulmonary artery

Question 5

what is the intermediate host foe heartworms

Answer 5

mosquitoes

Question 6

at what point in the lifecycle are heartworms infectious

Answer 6

L3

Question 7

T/F: microfilariae are not L3s

Answer 7

TRUE

Question 8

how long does it take for heartworms to mature in mosquitoes

Answer 8

10-14days

Question 9

isoxazolines _____ mosquito survival after blood feeding

Answer 9

decrease

Question 10

what is patency regarding heartworms

Answer 10

the time is takes for worms to mature and produce offspring in host (~`6-7 months post-infection)

Question 11

when can tests detect heartworms

Answer 11

6 months post-infection

Question 12

T/F: the # of adults in a host equals the # of microfilariae that infect the host

Answer 12

TRUE

Question 13

T/F: heartworms have a shorter life cycle in cats

Answer 13

FALSE

Question 14

what does aberrant migration of heartworms mean

Answer 14

migration to ectopic sites other than the pulmonary system

Question 15

T/F: usually heartworm infections in cats are <5 worms

Answer 15

TRUE

Question 16

how are cats infected with heartworm

Answer 16

bitten by mosquitoes that have fed on infected dogs

Question 17

what does the severity of heartworm disease depend on

Answer 17

1. # of adult worms
2. duration of infection
3. individual host response

Question 18

T/F: heartworm disease is a multiple organ disease

Answer 18

TRUE

Question 19

what are the 2 hallmarks of pulmonary arterial disease

Answer 19

1. inflammation (endarteritis damage from friction of flow)
2. villous thickening

Question 20

what is the pathologic appearance of pulmonary arterial disease

Answer 20

roughened, stippled appearance

Question 21

what does vessel thickening lead to

Answer 21

• loss of elasticity
• increased pressure
• R side enlargement, CHF w/ascites

Question 22

what is Wolbachia

Answer 22

endosymbionts in filarioid nematodes

Question 23

what is the role of Wolbachia in pathogenesis

Answer 23

associated proteins induce innate inflammatory response

Question 24

what are the 3 stages of feline HWD

Answer 24

1. worms reach lung vessels and induce an acute inflammatory response
2. dying worms induce inflammation and thromboembolism
3. chronic respiratory disease

Question 25

what is HARD

Answer 25

heartworm-associated respiratory disease (stage 1 feline HWD) commonly mistaken for asthma

Question 26

what are the 2 outcomes of stage 2 feline HWD

Answer 26

1. acute lung injury 2. sudden death

Question 27

what is the outcome of stage 3 feline HWD

Answer 27

hyperplasia of alveolar cells

Question 28

what is caval syndrome

Answer 28

large number of worms obstructs blood floe through the tricuspid valve and results in death within 12-72 hours

Question 29

how is caval syndrome treated

Answer 29

surgical removal of worms via jugular v.

Question 30

what are the symptoms of heartworm disease in dogs

Answer 30

1. chronic cough 2. dyspnea 3. decreased exercise tolerance 4. syncope 5. hemoptysis 6. CHF

Question 31

what percentage of feline heartworm cases are completely indoor cats

Answer 31

33%

Question 32

what are the symptoms of heartworm disease in cats

Answer 32

1. V+ unrelated to eating 2. lethargy, weight loss 3. systolic heart murmur 4. respiratory distress 5. seizures, ataxia 6. sudden death

Question 33

what does the heartworm antigen test detect

Answer 33

female uterine antigen

Question 34

what infections would not be detected with the antigen test

Answer 34

1. single-sex infections (male) 2. prepatent infection (<5months) 3. low burden

Question 35

ELISA is _____ or a lateral flow-based test

Answer 35

immunochromatographic

Question 36

T/F: immunodiagnostic test is available for cats but less sensitive

Answer 36

TRUE

Question 37

how do positive and negative results differ for a feline immunodiagnostic test

Answer 37

positive = has been infected before, but titers stay high after death negative = not been infected (at least not recently)

Question 38

T/F: a negative antigen test is definitive

Answer 38

FALSE

Question 39

when should puppies be tested for heartworm

Answer 39

7-8 months of age

Question 40

why should you microfilariae test

Answer 40

confirms positive antigen test and identifies reservoir of infection

Question 41

direct smears detect ____ of patent infections

Answer 41

75%

Question 42

knott's test

Answer 42

spin/concentrate blood sample and then look

Question 43

what is nonpathogenic, transmitted by fleas, but bears resemblance to MF of heartworms

Answer 43

A. (D.) reconditum

Question 44

what is the appearance of heartworm microfilariae versus A. reconditum

Answer 44

heartworm = tapered tip A. reconditum = blunt

Question 45

pulmonary thromboembolism can occur when after treatment

Answer 45

7-10 days

Question 46

T/F: particularly toxic drug given extravascular will lead to sloughing

Answer 46

TRUE

Question 47

why is the 3-dose melarsomine therapy recommended

Answer 47

increased safety and efficacy to kill more worms

Question 48

when should a repeat HW antigen test be done after treatment

Answer 48

9 months

Question 49

describe the 2-dose melarsomine treatment

Answer 49

day 0 -melarsomine injection 1 exercise restriction day 30 - melarsomine injection 2 exercise restriction

Question 50

describe the 3-dose melarsomine treatment

Answer 50

day 0 - melarsomine injection 1 exercise restriction day 30 - melarsomine injection 2 day 31 - melarsomine injection 3 exercise restriction

Question 51

does the 2-dose or 3-dose schedules diminish the degree of insult to pulmonary vasculature and tissue

Answer 51

3-dose

Question 52

T/F: ML preventative should be started before melarsomine tx

Answer 52

TRUE

Question 53

how many months is a patient on ML before receiving their first dose of melarsomine

Answer 53

2 months

Question 54

doxycycline is given for ____ prior to adulticide tx and reduces the risk of thromboembolism

Answer 54

28 days

Question 55

what drug may be added to an adulticide tx as an alternative

Answer 55

prednisone (during immiticide tx)

Question 56

how long should exercise be restricted during tx

Answer 56

1 month after 1st dose, 2 months after 2nd/3rd dose

Question 57

T/F: there are no satisfactory tx for feline HWD

Answer 57

TRUE

Question 58

how is HWD treated in cats

Answer 58

steroids + prophylaxis with monthly ML

Question 59

T/F: heartworm prophylaxis is recommended for warm seasons

Answer 59

FALSE - year-round

Question 60

what are oral macrocyclic lactones

Answer 60

1. ivermectin 2. milbemycin oxime 3. moxidectin

Question 61

what are topical macrocyclic lactones

Answer 61

1. moxidectin 2. selamectin

Question 62

what breed has a high sensitivity to macrocyclic lactones

Answer 62

collies

Question 63

T/F: slow kill programs NEED doxycycline

Answer 63

TRUE