Dirofilaria immitis in Dogs
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Questions and Answers

What role does the mosquito play in the life cycle of Dirofilaria immitis?

  • It serves as a definitive host.
  • It is where the adult worms reproduce.
  • It is a vector that transmits larvae to the definitive host. (correct)
  • It directly causes the heartworm disease.

    • What is the prepatent period for Dirofilaria immitis in dogs?

  • 2 to 3 months
  • 8 to 9 months
  • 4 to 5 months
  • 6 to 7 months (correct)

    • Which of the following statements accurately describes the definitive host for Dirofilaria immitis?

  • Cats are the primary definitive host.
  • Wild foxes are ideal definitive hosts.
  • Ferrets are commonly infested.
  • Dogs are the most common definitive host. (correct)

    • What happens when immature Dirofilaria immitis worms reach the pulmonary artery in humans?

    <p>They typically die and may trigger an inflammatory response.</p> Signup and view all the answers

    Which symptom in humans can be mistaken for lung cancer due to Dirofilaria immitis infestation?

    <p>Pulmonary nodules</p> Signup and view all the answers

    What is the average time it takes for new larvae to develop in the mosquito after it ingests L1?

    <p>10 to 30 days</p> Signup and view all the answers

    What is the primary location of adult Dirofilaria immitis within its definitive host?

    <p>Pulmonary arteries and right ventricle</p> Signup and view all the answers

    What is the purpose of the antigen test for dogs older than 6 months?

    <p>To detect the presence of adult female worms</p> Signup and view all the answers

    What is the initial treatment sequence for heartworm disease?

    <p>Administer microfilaricide first, then doxycycline, followed by adulticide</p> Signup and view all the answers

    What should be done if a dog is antigen negative but shows no circulating microfilariae?

    <p>Administer heartworm preventative and repeat the test in 6 months</p> Signup and view all the answers

    During the prepatent period, which of the following is true regarding heartworm testing?

    <p>Antigen levels may be too low to be detected</p> Signup and view all the answers

    What is the purpose of administering doxycycline during heartworm treatment?

    <p>To reduce the population of Wolbachia spp.</p> Signup and view all the answers

    Which test is NOT typically used for pre-treatment evaluation in heartworm therapy?

    <p>Heartworm antigen test</p> Signup and view all the answers

    What complication may occur 7-10 days after adulticide treatment?

    <p>Pulmonary thromboembolism</p> Signup and view all the answers

    Where is the adulticide Melarsomine dihydrochloride administered?

    <p>Intramuscularly in epaxial muscles</p> Signup and view all the answers

    What is the recommended duration to restrict exercise after treatment?

    <p>4 to 6 weeks</p> Signup and view all the answers

    Which of the following is a method of preventing heartworm infestation?

    <p>Monthly oral or topical dosing of macrocyclic lactones</p> Signup and view all the answers

    What does the term dyspnea refer to?

    <p>Difficulty breathing</p> Signup and view all the answers

    What happens if there is a lapse in monthly dosing of more than 2 weeks?

    <p>The risk of developing adult Dirofilaria immitis increases</p> Signup and view all the answers

    Which of the following describes hemoptysis?

    <p>Spitting up blood from the respiratory tract</p> Signup and view all the answers

    What is a thrombus?

    <p>A clot that is attached to the vessel wall</p> Signup and view all the answers

    Which medication is formulated as a sustained-release for heartworm prevention?

    <p>Moxidectin</p> Signup and view all the answers

    What is the main consequence of performing an Ag test too early after adulticide treatment?

    <p>It may yield false positive results.</p> Signup and view all the answers

    What describes the prepatent period for heartworm infestation in cats?

    <p>Approximately 8 months</p> Signup and view all the answers

    What is the typical duration of the entire heartworm life cycle in dogs?

    <p>6 to 7 months</p> Signup and view all the answers

    Which of the following statements is true regarding heartworm infestation in cats?

    <p>It takes greater exposure for heartworm infestation to occur in cats than in dogs.</p> Signup and view all the answers

    What is a common unique feature of heartworm infection in cats?

    <p>Ectopic sites for adult worms are more common</p> Signup and view all the answers

    Which clinical sign is NOT typically associated with heartworm disease (HWD)?

    <p>Increased appetite</p> Signup and view all the answers

    Which test is used to detect and measure antigens or antibodies in a sample?

    <p>ELISA</p> Signup and view all the answers

    How long after infestation can a host test negative for both antigen and microfilariae tests?

    <p>6 to 7 months</p> Signup and view all the answers

    What is a characteristic of hemoglobinemia?

    <p>Presence of free hemoglobin in circulating plasma</p> Signup and view all the answers

    What is a common method used to diagnose heartworm disease?

    <p>Modified Knott test</p> Signup and view all the answers

    Which pathological change does heartworm infestation cause to the pulmonary arteries?

    <p>Vessel walls thicken and lumen narrows</p> Signup and view all the answers

    What is the primary cause of Caval Syndrome related to heartworm disease?

    <p>Heartworms packed into the vena cava</p> Signup and view all the answers

    What effect does heartworm disease have on right-sided congestive heart failure (CHF)?

    <p>Obstruction of vessels and heart chambers</p> Signup and view all the answers

    What is the typical length of female heartworms?

    <p>300 mm (12 inches)</p> Signup and view all the answers

    What role do adult female heartworms play in the diagnosis of heartworm disease?

    <p>Produce microfilariae and antigen</p> Signup and view all the answers

    Which condition is characterized by profound general ill health and malnutrition due to heartworm infestation?

    <p>Cachexia</p> Signup and view all the answers

    What is a common characteristic of microfilariae testing in cats?

    <p>Microfilariae rarely present, making testing unreliable</p> Signup and view all the answers

    Which test is recommended alongside Ag and Ab testing for diagnosing heartworm in cats?

    <p>Echocardiography</p> Signup and view all the answers

    What is the recommended action for treating heartworm in cats?

    <p>Wait for spontaneous cure without treatment</p> Signup and view all the answers

    What is a risk associated with the use of chemotherapy for treating heartworms in cats?

    <p>It may result in severe post-treatment complications</p> Signup and view all the answers

    Which of the following is considered safe for preventative treatment without prior testing in cats?

    <p>Preventative treatment can start at 8 weeks of age</p> Signup and view all the answers

    Study Notes

    Dirofilaria immitis ("Heartworm") in Dogs

    • Etiologic Species: Dirofilaria immitis
    • Life Cycle: Indirect, involving a mosquito intermediate host
    • Transmission: Mosquito bites infected dogs, transmitting immature stages
    • Prepatent Period: Dogs: 6-7 months, Cats: ~8 months
    • Definitive Host: Dogs, Cats, Ferrets, and Wild Animals (Foxes, Coyotes, Sea Lions)
    • Zoonotic Potential: Humans can be infected, but usually do not develop a patent infection
    • Pulmonary Nodules ("Coin Lesions"): Possible indication of heartworm infection, sometimes mistaken for lung cancer
    • Cat Considerations: Information is primarily for dogs, and cats will be discussed separately

    Distribution of Heartworms

    • Geographic Distribution: Originally found along the Atlantic and Gulf Coasts, but now widespread across the US, with lower case numbers in the Rocky Mountain West and Desert Southwest.
    • Geographic Trends: Currently spreading up the Colorado River Valley from Grand Junction.

    Heartworm Life Cycle

    • Adult Location: Primarily in pulmonary arteries and right heart
    • Female Reproduction: Produce microfilariae (L1)
    • Microfilariae Circulation: Present in blood

    Heartworm Diagnostics

    • Antigen Tests: Detect presence of adult worms; test should be negative by 6-7 months
    • Microfilaria Testing: Detect presence of microfilariae is blood; test should be negative until 6-7 months
    • Other Tests: Modified Knott test and Millipore filter for microfilariae, radiography can show signs of the disease

    Heartworm Treatment

    • Pretreatment Evaluation: Including urinalysis, CBC, and chemistry profile
    • Treatment Sequence: Microfilaricide 2 treatments, Doxycycline for 30 days, Adulticide (Melarsomine dihydrochloride) in three doses.
    • Post-Treatment Care: Careful monitoring for potential complications

    Feline Heartworm Disease

    • Susceptibility: Cats are more resistant but can still be infected
    • Infestation Challenges: Need higher levels of exposure for infection
    • Worm Burden: Lower worm burden than in dogs; usually 1-5 worms (but up to 65)
    • Prepatent Period: 8 months
    • Clinical Signs Considerations: Can be present during both stages of the disease, and symptoms can appear different than in dogs
    • Diagnostic Challenges: Different from dogs; Ag and Ab testing are more commonly used in cats due to microfilariae being rare.

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    Related Documents

    Canine and Feline Heartworm Notes PDF

    Description

    This quiz covers the essential information about Dirofilaria immitis, commonly known as heartworm, in dogs. It includes details about its life cycle, transmission, geographic distribution, and implications for both dogs and cats. Test your understanding of this important canine health issue.

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