Case 1

A 12 year-old intact male Poodle with history of CCVHD since several years ago. Was treated with Vetmedin, Fortekor, Sildenafil, Furosemide. Noted more coughing and increased respiratory effort in these few nights. Patient was presented last night due to acute collapse, weakness and incontinence. Physical examination found muffled heart sound, crackle lung sound and tachypnea. Chest radiograph revealed severe cardiomegaly, globoid cardiac silhouette, with clear lung fields.

Echocardiographic findings:


Fig. 1. Right parasternal long axis four chamber view. Massive pericardial effusion and secondary cardiac tamponade.


Fig. 2. Homogeneous echogenic object in pericardial sac, surrounding the ventricles.


Fig. 3 Right parasternal short axis view at papillary muscle level. Large homogeneous echogenic object in pericardial sac.


Fig. 4. Right parasternal heartbase short axis view. Severe left atrial enlargement documented, LA/Ao ratio = 2.32.


Fig. 5 Left parasternal apical four chamber view. Large homogeneous echogenic object in pericardial sac.


Fig. 6. Left parasternal apical four chamber view. Severe mitral valve regurgitation documented. Note there is some echogenic objects in pericardial sac.

Echocardiographic diagnosis:

  • Severe pericardial effusion, cardiac tamponade, clot formation in pericardial sac
  • Left atrial tear/rupture, most likely secondary to severe LA enlargement and CCVHD
  • LA enlargement(can be underestimated due to rupture)
  • Stage C CCVHD
  • Mild TR, no pulmonary hypertension
  • Ventricular arrhythmia


Left atrial rupture is a rare consequence of CCVHD in dogs, accounting 2% of all causes of pericardial effusion. It is more common in male dogs, and uncommon in cats. It is mostly acute onset due to rapid accumulation of blood in the pericardium, causing cardiogenic shock and death from a smaller amount of fluid than other causes of pericardial effusion. Diagnosis of left atrial rupture requires echocardiography, however, absence of a thrombus within the pericardial space may not rule out left atrial rupture, as if the accumulation of the blood was slow or if the rupture did not occur acutely, large visible clots may not be seen due to fibrinolysis.

Acute treatment of left atrial rupture is pericardiocentesis if cardiac tamponade is presented. The wound on left atrium maybe obstructed by the clot, and after pericardiocentesis, diuretics are recommended to decrease LA pressure and size. However, if the wound is not obstructed, bleeding may recur and the prognosis would be very poor.

Although rare, left atrial rupture resulting in pericardial effusion should be considered in older small- to medium-sized dogs presenting with collapse, and dyspnea.

Case 1 is written by Dr Eason, December 2017


  1. Erica L. Reineke et al. Left atrial rupture in dogs: 14 cases (1990-2005). Journal of Veterinary Emergency and Critical Care 18(2) 2008
  2. Reid K. Nakamura et al. Left Atrial Rupture Secondary to Myxomatous Mitral Valve Disease in 11 Dogs. J Am Anim Hosp Assoc 2014