Canine ehrlichiosis is a tick borne rickettsial infection that affects dogs worldwide. The objective of this study was to explore the involvement of Ehrlichia canis in the fatal acute respiratory distress observed in 23 pups; mainly purebred and mixed German shepherds, and Labrador retrievers, aged less than 6 months. The pups were presented with acute and severe dyspnoea, inappetance, inactivity, depression, wheezing, normal to weak pulse, tachycardia, tachypnoea and hypoxemia. Some had 2/6 to 3/6 grade right or bilateral systolic apical cardiac murmurs, splenomegaly, lymphadenomegaly and mild to moderate ascites. Hematological and biochemical analysis indicated regenerative anemia, thrombocytopenia, leukocytosis and hypoalbuminemia with blood smear positive for Ehrlichia canis. The coagulation profile of prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen levels were elevated. Thoracic radiography indicated interstitial pulmonary infiltrates, right sided cardiomegaly, and both pulmonary arterial and venous congestion. Echocardiography proved the pups had pulmonary arterial hypertension, and rightsided congestive heart failure (RHF). It was suspected that, PH and RHF observed were caused by cor pulmonale secondary to pulmonary pathology associated with canine ehrlichiosis. The treatment protocol comprised of anti-rickettsial agent, phosphodiesterase-5 inhibitor, bronchodilators, diuretics, antioxidants, vitamin B and amino acid supplements, and in some, plasma transfusion and vitamin K supplementation. The mortality rate was high with 15 dying from the total number. Postmortem of dead pups revealed, pulmonary interstitial infiltrates of lymphocytes and macrophages, pulmonary hemorrhages, right sided cardiomegaly. The unique findings of this study were; the association of acute canine ehrlichiosis in pups with PH and RHF, utilization of wheezing and dyspnoea as a screening criteria to identify acute canine ehrlichiosis in pups and association of acute liver impairment mediated dysfunction of secondary hemostasis and the pulmonary hemorrhages observed in pups with canine ehrlichiosis. 1397905837.php