A 4-year-old, male local dog was referred to University Veterinary Hospital-Universiti Putra Malaysia (UVH-UPM) due to
dyspnoea and ascites. Full diagnostic investigations inclusive of blood haematology, serum biochemistry, blood smear examinations
for haemopathogens, heartworm antigen test, thoracic and abdominal radiography and echocardiography were conducted. A
diagnosis of severe heartworm disease was made from the positive heartworm antigen test, the presence of heartworms on
echocardiography and the accompanying advanced clinical findings. This was the first case of right-sided heart failure due to severe
heartworm disease with concurrent pulmonary hypertension diagnosed in UVH-UPM from which the moribund dog was
successfully stabilised during hospitalisation.