CV parasites

Question 1

What is canine heartworm

Answer 1

Dirofilaria Immitis

Question 2

What factors affect the distribution of D. Immitis

Answer 2

Requires water temperature to be above 27 degrees for 2 weeks , mosquito breeding

Question 3

Describe the D. Immitis life cycle

Answer 3

1. Mosquito takes L1 from blood of infected patient
2. L1-L3 in mosquito
3. mosquito bites another uninfected dog and transfers L3 into their blood
4. L4/L5/Adult develop in the dogs right heart and pulmonary vessels

Question 4

What are the clinicl features of a D. immitis infection

Answer 4

• Exercise intolerance
• Hydrothorax
• Hydroperitoneum
• Chronic cough
• Dyspnoea
• Haemoptysis
• Eosinophillia in lung
• Oedema in lung parenchyma

Question 5

How does D. Immitis cause hypertension

Answer 5

inner lining of the blood vessel gets disrupted and this leads to platelet influx and production of platelet derived growth factor. This increases proliferation of medial smooth muscle cells and fibroblasts. causing blood vessels walls to thicken

Question 6

Which cells produce histamine

Answer 6

Basophils and Mast cells

Question 7

What bacteria do D. Immitis carry

Answer 7

Wolbachia

Question 8

Why do neutrophils respond to DE. immitis

Answer 8

Becaus D. immitis as it carries Wolbachia which is a type of bacteria

Question 9

How do you diagnose canine heartworm

Answer 9

- Complete blood count to lok for microfilariae in blood
X-rays 
Echocardiogram
Tracheal wash
ELISA

Question 10

How do heartworms appear on a echocardiogram

Answer 10

very echogenic

Question 11

What are the limitations of complete blood count to diagnose D. immitis

Answer 11

some other disease will give similar results

Question 12

What are the limitations of blood smears in testing for D. Immitis

Answer 12

microfilariae may not be seen if few are present

Question 13

What are the limitations of echocardiograms when diagnosing D. immitis

Answer 13

May be difficult to interpret

Question 14

What are the limitations of radiology when diagnosing D. immitis

Answer 14

Signs may be similar to other diseases

Question 15

What are the limitations of ELISA tests when diagnosing D. Immitis

Answer 15

Only adult female antigens detected

False negatives occur- if immature females present or male only infection

Question 16

How can D. immitis cause thrombocytes

Answer 16

Worms die, decompose and can break into little bits, particles can get lodged in different areas

Question 17

What is the best way to deal with a heavy infection of D. immitis so thrombocytes don’t occur

Answer 17

Surgical removal

Question 18

What are the issues with surgical removal of D. immitis

Answer 18

prognosis and complications from treatment as well as cost need to be discussed with the client

Question 19

How can you tell the difference between D. reconditum and D. immitis microfilariae

Answer 19

acid phosphate test- only stains 2 spots in D. Immitis

Question 20

Are cats susceptible to D. immitis

Answer 20

Yes, but not as much as dogs

Question 21

What is caval syndrome

Answer 21

obstruction of blood flow from the vena cava caused by heavy heartworm infestation

Question 22

Why is it so hard to diagnose D. immitis in cats

Answer 22

they are amicroflaraemic, ELISA analysis isn’t good because worm count is low and single sex infections occur more