Canis ISSN: 2398-2942

Radiology: cardiac examination

Contributor(s): Fraser McConnell, Jordi Lopez-Alvarez


  • Radiology plays an important part in the diagnosis and management of cardiac disease. It allows assessment of the pulmonary vasculature and lungs which is not possible with echocardiology.
  • Radiology also plays an important role in the differentiation of cardiac and respiratory cough.
    Follow the diagnostic tree for the Radiographic Detection of Canine Cardiomegaly Radiographic Detection of Canine Cardiomegaly.

Radiographic considerations

  • The radiographic technique is particularly important in thoracic imaging Radiography: thorax.


  • For the investigation of cardiac disease a right lateral projection Thorax normal - radiograph lateral and dorsoventral (DV) projection should be taken.
  • Careful positioning is important, particularly to prevent rotation of the thorax which can lead to a false impression of mild left atrial enlargement.
    This effect is most marked in deep chested dogs, eg Doberman pinscher.
  • The heart has a complex shape and even small degrees of rotation can make assessment of chamber size unreliable, particularly on the DV projection.


  • Care must be taken to ensure that the stress of radiography will not cause further decompensation in animals with congestive heart failure.
  • Oxygen supplementation via a face mask may help ease the patient's respiratory distress improving the quality of the radiographs.
  • A DV projection can usually be taken without sedation in dyspneic animals.
  • The lateral projection can then be taken after the patient's condition has been stabilized.
  • In most cases, however, it is safer to give a low dose of sedation Sedation / sedative protocols if required than to struggle with a dyspneic animal.
  • The intramuscular or intravenous combination of butorphanol Butorphanol and acepromazine Acepromazine maleate ) are generally used in cardiac patients.
    Alpha 2 agonists should be avoided.

Exposure factors

  • A high kV low mA technique should be used to reduce contrast within the thorax and allow exposure times to be kept as short as possible.
  • Movement blur Radiography: film faults is one of the most common problems in thoracic radiography, particularly in dyspneic patients.
  • This can be minimized by using a high kV, dispensing with a grid and using a fast film/screen Radiography: X-ray film combination.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Gugjoo M B, Hoque M, Saxena A C et al (2013) Vertebral scale system to measure heart size in dogs in thoracic radiographs. Advances in Animal and Veterinary Sciences 1 (1), 1-4 VetMedResource.
  • Lamb C R, Wikeley H, Boswood A et al (2001) Use of breed-specific ranges for the vertebral heart scale as an aid to the radiographic diagnosis of cardiac disease in dogs. Vet Rec 148 (23), 707-711 PubMed.
  • Sleeper M M & Buchanan J W (2001) Vertebral scale system to measure heart size in growing puppies. JAVMA 219 (1), 57-59 PubMed.
  • Buchanan J W & Bücheler J (1995) Vertebral scale system to measure canine heart size on radiographs. JAVMA 206 (2), 194-199 PubMed.