Cardiovascular Flashcards
(35 cards)
What species of animal are the most suitable definitive hosts for Dirofilaria immitis?
Domestic dogs and some wild canids. Cats can get infected but they are not as suitable as dogs.
What is the average lifespan of adult Dirofilaria?
In dogs: 5-7 years
In cats: 2-3 years
What is the intermediate host for Dirofilaria immitis?
Female mosquitoes (Culex, Aedes and Anopheles spp)
What is the name of the intracellular bacteria harboured in Dirofilarial worms?
Wolbachia pipientis
What is the life cycle length of Dirofilaria immitis?
7-9 months
How do the intermediate hosts get infected with Dirofilaria immitis?
The mosquitoes get infected with microfilariae when taking a blood meal.
What happens to the microfilaria after it is taken up by the mosquito?
At 26-28°C L1 -> L2 -> L3 over the span of about 2 weeks.
How does the definitive host get infected?
While the mosquito is taking a blood meal the developed L3 will get deposited on the skin of the host and enter via the puncture wound made by the mosquito.
Who is most susceptible?
All dogs regardless of age, sex or habitat are susceptible to heart worm infection.
The pathogenesis of D. immitis depends on what?
Number of worms present.
Duration of the infection.
Level of activity of the dog.
Size of the dogs.
How big a role do microfilaria play in the pathogenesis of D. immitis infections?
They seem to play a minor role but will cause pneumonitis and glomerulonephritis.
What is Cor Pulmonale?
Disruption of endothelial cell junctions and denuding of intimal surface -> intimal proliferation in response to parasite -> blockage of the lumen -> pulmonary artery and large branches get dilated, thickened and develop ridged intimas -> congestive heart failure.
What is Caval Syndrome?
D. immitis are also in the right atrium and caudal vena cava causing a partial inflow obstruction -> massive haemolysis (haemoglobinuria) -> liver failure -> passive congestion (ascites etc.) -> circulatory shock/death
What are the clinical signs associated with infections with D. immitis?
Reduced exercise tolerance Fatigue -> lethargy Weight loss despite good appetite Dyspnoea Syncope and hemoptysis Abnormal pulmonary and cardiac sounds
In a dog with caval syndrome, if the heartworms are not removed surgically, how soon may death occur?
Within 2-3 days.
How would you diagnose a heart worm infection?
Clinical signs
History and clinical examination
Confirmed by detection of microfilaria and detection of parasite antigens or specific antibodies
You suspect heart worm infection of one of your canine patients. Upon inspection of a blood sample you cannot detect microfilaria. Does that mean this dog is not infected with D. immitis?
No, the dog may have an occult infection (no circulating microfilaria). This may be due to a prepatent infection, single sex infection or most commonly immunologic or drug medicated elimination of the microfilaria
What are the best ways to detect microfilaria of D. immitis?
Blood smear
Concentration techniques
Microfilaria of D. immitis need to be differentiated from microfilaria of which other parasite?
Acanthocheilonema reconditum
The amount of antigen from female D. immitis in the circulation is indicative of what?
Age, number and health of the female parasites.
When would detection of D. immitis specific antibody be indicated?
To diagnose or rule out heart worm infections in cats.
When clinical presentation of heart worm disease does not require immediate intervention, it is beneficial to administer:
MLs for up to 3 months prior to adulticide treatment
Doxycycline for one month before adulticide treatment (Wolbachia)
What is the adulticide used for killing adult stages of Dirofilaria immitis?
Melarsomine dihydrochloride (Immiticide)
What life cycle stages will you target to prevent heart worm infection?
L3 and L4 with MLs
