History
A 6-year-old Hereford cow was evaluated for recurrent free gas bloat and fever of unknown origin. The cow had aborted an approximately 8-month gestational age fetus 7 days earlier and had been clinically normal prior to the abortion. The cow was born on the farm and had had several calves without complications.
Abnormalities detected during physical examination included mild tachycardia (96 beats/min; reference range, 60 to 84 beats/min), tachypnea (38 breaths/min; reference range, 18 to 28 breaths/min), and an intermittent cough. Adventitious sounds were detected during auscultation of the ventral portion of the thorax on the right side. Results of CBC and serum biochemical analyses indicated a mature neutrophilia (neutrophil count, 10,100 cells/μL; reference range, 600 to 4,000 cells/μL), hyperglobulinemia (6.8 g/dL; reference range, 4.1 to 5.1 g/dL), and a slight increase in serum γ-glutamyltransferase activity (36 U/L; reference range, 12 to 30 U/L). An IV catheter was placed in the left jugular vein, and potassium G penicillin (22,000 U/kg [10,000 U/lb], IV, q 6 h) and ceftiofur (2.2 mg/kg [1 mg/lb], IV, q 24 h) were administered.
The cow continued to bloat intermittently during the next 48 hours, had intermittent pyrexia, and had a moderate amount of hemorrhagic discharge from the right naris. Radiographs of the thorax were obtained (Figure 1).
Lateral radiographic views of the thorax of a 6-year-old cow evaluated for fever of unknown origin and bloat.
Citation: Journal of the American Veterinary Medical Association 228, 1; 10.2460/javma.228.1.35
Radiographic Findings and Interpretation
A mild bronchial and interstitial pattern is evident in the caudodorsal lung fields, compatible with chronic bronchointerstitial pneumonia (Figure 2). Free air (pneumomediastinum) surrounds the aorta. The caudal vena cava widens adjacent to the diaphragm, compatible with a thrombus, diaphragmatic hernia, or pulmonary mass. The diameter of the cranial portion of the caudal vena cava appears small, which is compatible with stenosis attributable to intraluminal obstruction or narrowing during normal cardiac cycle changes. Multiple subtle ovoid lucencies were detected in the caudodorsal lung fields, compatible with bullae or gas-filled abscesses; however, these findings did not reproduce well.
Same radiographic views as in Figure 1. A—Notice the stenotic caudal vena cava (arrowhead) and the soft tissue opacity expanding the caudal vena cava at the level of the diaphragm (arrows). B—Notice the bronchointerstitial lung infiltrate in the caudodorsal lung fields (white arrows) and the pneumomediastinum surrounding the aorta (black arrows).
Citation: Journal of the American Veterinary Medical Association 228, 1; 10.2460/javma.228.1.35
Comments
Ultrasonographic evaluation of the liver parenchyma and vena cava at the hilus was normal. The owner chose to euthanize the cow for economic reasons. Necropsy revealed a large (10 × 5 × 2.5-cm) firm multinodular thrombus obstructing the caudal vena cava at the level of the diaphragm. The intrathoracic portion of the caudal vena cava between the heart and the thrombus was markedly narrowed, consistent with the radiographic findings. Additionally, there was interstitial emphysema within the mediastinum and numerous multifocal, caseous abscesses throughout the lungs, myocardium, and both renal cortices. Several small (< 2 cm) interlobular pulmonary bullae were detected bilaterally; however, the lungs collapsed when the diaphragm was punctured.
Caudal vena caval thrombosis is most commonly associated with hepatic abscess formation secondary to acute, subacute, or chronic rumen acidosis.1,2 In the cow of this report, pathologic lesions were not detected in the liver or rumen, and there was no history of sudden access to highly fermentable feedstuffs. However, necropsy revealed evidence of thromboembolic disease in multiple organs. Clinicopathologic abnormalities were consistent with chronic inflammation. In addition to hepatic abscesses, caudal vena caval thrombosis may be caused by conditions associated with sepsis, including mastitis, metritis, phlebitis, and interdigital necrobacillosis.1,3 Radiographic and necropsy findings in the cow of this report were compatible with chronic pneumonia caused by embolic showering from a prior pyogenic focus. Pneumomediastinum and bullae were consistent with prior observations documenting thoracic air leak syndromes associated with tachypnea or dyspnea in cattle with chronic pneumonia.4 It was possible that pneumomediastinum may have developed secondary to gas tracking along soft tissue planes from the catheter site or in association with jugular phlebitis; however, no antemortem or postmortem evidence to support this was detected.
Clinical signs of caudal vena caval thrombosis include tachycardia, tachypnea, auscultable rales, persistent or recurrent pyrexia, anemia, and hemoptysis.3 Epistaxis of varying severity and frequency may be seen.1 The cow of this report had intermittent epistaxis during hospitalization.
In valuable cattle, high doses of penicillin can be used in addition to diuretics and anti-inflammatory drugs.3 However, the prognosis is guarded to poor.1,3
- 1↑
Wikse S. Vena caval thrombosis and metastatic pneumonia. In: Smith BP, ed. Large animal internal medicine. 3rd ed. St Louis: CV Mosby Co, 2002;587–588.
- 2
Rebhun WC. Caudal vena caval thrombosis. In: Rebhun WC, ed. Diseases of dairy cattle. Baltimore: The Williams & Wilkins Co, 1995;91–93.
- 3↑
Rebhun WC, Rendano VT, Dill SG, et al. Caudal vena caval thrombosis in 4 cattle with acute dyspnea. J Am Vet Med Assoc 1980;176:1366–1369.
- 4↑
Slack JA, Thomas CB, Peek SF. Pneumothorax in dairy cattle: 30 cases (1990–2003). J Am Vet Med Assoc 2004;225:732–735.
