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Heartworm (D. immitis)
Infectious DiseaseParasiteCanineFelineNew
Key Points
  • Heartworm is caused by Dirofilaria immitis and transmitted by mosquito vectors
  • Clinical disease ranges from asymptomatic to caval syndrome and sudden death
  • The most common signs in dogs include cough, exercise intolerance, dyspnoea and ascites
  • Diagnosis is dogs uses both antigen and microfilariae testing, with imaging to stage severity and assess complications
  • The AHS-recommended treatment for dogs is the 3-dose melarsomine protocol, with doxycycline and a macrocyclic lactone beforehand and strict exercise restriction throughout
  • Year-round macrocyclic lactone prevention is recommended along with annual screening
  • In cats, even low burdens of immature worms can trigger heartworm-associated respiratory disease (HARD) which can be severe and fatal
    • There is no approved adulticide therapy available for cats
Differential Diagnoses
  1. Congestive heart failure
  2. Chronic bronchitis / feline asthma
  3. Pulmonary thromboembolism
  4. Myxomatous mitral valve disease
Overview
Aetiology
Clinical Signs
Diagnosis
Treatment
Prevention
Resources
Overview

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Aetiology

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Clinical Signs

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Diagnosis

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Treatment

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Prevention

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Resources

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Educational content only. This factsheet is for general veterinary education and is not a substitute for professional veterinary advice, diagnosis, or treatment. Not for use in an emergency — contact a veterinarian or emergency service. Full disclaimer →