Caudal Vena Cava Thrombosis in Cows

Background: The caudal vena cava thrombosis (CVCT) is a serious disease that affects cattle, and due to be commonly a fatal pathology, it causes economic losses for producers and national livestock. Thus, the present study describes the epidemiological, clinical, ultrasonographic imaging and pathological findings in 4 cattle with CVCT attended at the Veterinary Hospital (HV) of the Institute of Veterinary Medicine (IMV) of the Federal University of Pará (UFPA). Cases: The cows were crossbreds of the Gir x Holstein and Jersey x Holstein breeds, aged between 4 and 8-year-old, raised in the semi-extensive and intensive systems. The main clinical signs were pale mucous membranes, reluctance to move, markedly positive venous pulse, engorged jugular with positive stasis test and serous to mucopurulent nasal exudation. The auscultation of the lung fields revealed tachypnea, silent areas, wheezing, pleural friction, in addition to coughing, expiratory dyspnea, mouth breathing and expiratory grunts. One animal had severe hemoptysis. The ultrasound examination performed in a bovine revealed a circular and dilated caudal vena cava in cross-section. Laboratorial tests in 3 cows revealed anemia and leukocytosis with neutrophil left shift, in addition to increased liver enzymes. At necropsy, all cattle had thrombi in the hepatic segment of the vena cava caudal. In the lung, multiple abscesses and areas of parenchymal consolidation, crateriform areas, as well as thrombi in the arteries were observed. Pleural effusion and ascites where seen in all cows. Clotted blood was seen in the trachea, bronchi and on rumen contents of an animal. Histopathological alterations seen in the liver were centrilobular hepatocytes with frequent intensely eosinophilic cytoplasm, and pyknotic, karyorrhexic or absent nuclei and cell borders barely distinguishable. In the lung, there were nodular and random formations, with a thick wall of mature connective tissue and a central area full of cellular debris, necrotic cells, intact and degenerated neutrophils (abscesses). Discussion: The set of diagnostic tools that includes epidemiology, clinical signs and clinical examinations, ultrasound, necropsy and histopathology were efficient in the diagnosis of CVCT. The possible causes that led the cows to develop CVCT were diffuse septic pododermatitis in the medial nail of the right pelvic limb associated with traumatic reticuloabomasitis and liver abscesses. In 1 animal, it was not possible to establish the probable cause of CVCT, but for the other 3 cows in the present study, the probable causes are in agreement with studies that have shown that this disease can occur as a sequel to several septic conditions such as: jugular phlebitis, mastitis, hoof rot, enteritis, pneumonia, traumatic reticulopericarditis, acidosis and rumen laminitis, as well as omphalophlebitis in calves. The tachypnea, serous to purulent nasal exudation, pulmonary wheezing, pleural friction, coughing, expiratory dyspnea, usually with open mouth breathing and expiratory grunts evidenced in the animals of this study, occurred as a result of embolic abscess pneumonia. The presence of multiple lung abscesses, areas of parenchymal consolidation, crateriform foci and thrombi in the pulmonary arteries and chronic suppurative pneumonia, found at necropsy of the animals in the present study, are related to the development of a thrombus in the caudal vena cava that detaches and embolizes and lodges in the pulmonary arteries. The histopathological findings in one animal are compatible with lesions found at necropsy and draw attention to embolic pneumonia and liver lesions, which, are related to thrombi in pulmonary arteries and abscesses formed from CVCT, as well as venous stasis exerted in the return circulation. Keywords: thrombi, venous stasis, circular caudal vena cava, Amazon Biome.