Aortic Thromboembolism as a Consequence of Bacterial Endocarditis Causing Acute Ischemic Neuromyopathy in a Dog

Abstract

Background: Aortic thromboembolism (ATE) is a potentially fatal and rare condition in dogs. Ischemic neuromyopathy is main consequence, characterized by paraparesis or paraplegia, loss of femoral pulses, pain and hypothermia in distal part of affected limbs. In felines, affection is primarily associated with heart problems, whereas in dogs, condition is due to diseases which compromise the blood flow, such as, hyperadrenocorticism, immune-mediated hemolytic anemia, disseminated intravascular coagulation, sepsis, and more rarely cardiac problems. The aim of this article is describe a case of acute aortic thromboembolism due to bacterial endocarditis in a dog.

Case: A female, 9-year-old dog, weighing 28.5 kg, was referred for examination due to acute paraparesis and pain. Patient showed cyanosis in nail beds and cold extremities in hind limbs, heart murmur degree V / IV, and bilateral absence of femoral arterial pulse. Due to suspicion of ATE, patient was treated with heparin, aspirin and tramadol, however it came to die less than 24 h after initial care. At necropsy, there was pulmonary edema, moderate hyperemia and severe tricuspid mitral valve. A thrombus with 3.0 cm of diameter in left atrium was found. At beginning of aorta there was also a thrombus measuring 5.0 cm x 0.3 cm x 0.3 cm and other thrombus in abdominal aortic trifurcation measuring 3.0 cm x 0.5 cm x 0.5 cm. Kidneys showed diffusely marked coagulative necrosis associated with extensive congestion and hemorrhage in corticomedullar region. Multiples focus of dark red coloration lesions and elevated surfaces ranging from 0.5 to 3.0 cm of diameter were observed in the spleen. Histological examination of heart valves showed presence of moderate amounts of degenerate neutrophils indicating bacterial endocarditis, whereas, same exam of kidneys, interstitial inflammatory infiltrate mostly constituted by a small quantity of degenerated neutrophils and lymphocytes was found. Thus, final diagnosis was ATE, resulting from bacterial endocarditis.

Discussion: Aortic thromboembolism is an uncommon disease in dogs, generally affecting patients ranging from medium to big-sized and middle-aged to elderly dogs. Majority of dogs show chronic signs, whilst acute presentation, described herein, is uncommon. Clinical signs, showed by our patient were similar to what occur in felines with same disease, being absence of femoral pulse pathognomonic for both species. Patients can present partial or full obstruction to aortic trifurcation, with signs which range from weakness to paraplegia, as a consequence of ischemic neuromyopathy, as well observed in the present report. On post-mortem examination clinical suspicion of ATE was confirmed, however, unlike majority of reports of this condition in literature, two more thrombus were also identified. Due to acute picture and fast evolution to death, complementary exams, such as, two-dimensional ultrasound or Doppler, which are effective in viewing of presence of occlusion of aortic and decrease of blood flow, were not possible to accomplish. Severity and fatal evolution of this picture also prevented both etiologic diagnosis and treatment to be conducted. In consulted literature, descriptions of ATE due to bacterial endocarditis in dogs weren’t found, but it is believed that in present report, ATE may have occurred due to bacterial endocarditis. Unfortunately, both prognoses of bacterial endocarditis as ATE are poor and association of these two affections is probably associated with fast worsening picture and evolution to death.

Keywords: embolism, endocarditis, aortic diseases, paraplegia.