Bovis ISSN 2398-2993

Pulmonary thromboembolism

Contributor(s): Louise Cox-O’Shea , Gayle Hallowell

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Introduction

  • Occlusion of pulmonary blood vessel by clot or embolus.
  • In cattle most commonly caused by embolus from thrombus of vena cava secondary to liver abscessation.
  • Cause: hepatic abscess, phlebitis, cardiac disease, neoplasia, disseminated intravascular coagulopathy (DIC), sepsis, many systemic diseases, idiopathic.
  • Signs: acute onset respiratory distress, tachypnea.
  • Diagnosis: clinical signs, blood work, echocardiography. Rarely will radiography or ECG be practical or helpful in cattle.
  • Treatment: oxygen therapy, anticoagulant, treat underlying cause.
  • Prognosis: guarded to poor.

Pathogenesis

Etiology

Predisposing factors

General

  • Hepatic abscess due to hematogenous spread from infection elsewhere in body.
  • Hepatic abscess secondary to rumenitis (Excess carbohydrate -> ruminal acidosis-> rumenitis).

 

Pathophysiology

  • Occlusion of pulmonary vasculature by clot or embolus.
  • Clot formation requires one or more of the following: hypercoagulable state, vascular stasis or damage to the vascular endothelium.
  • Clot usually forms as a result of disease in organs other than lungs.
  • Various mechanisms of clot formation, eg: 
    • Hepatic abscess -> Infiltration of vena cava-> thrombophlebitis -> thrombus formation -> embolism to pulmonary vasculature. (often -> pneumonia and multiple pulmonary abscess formation).
    • IV catheters IV catheters.
    • Cardiac disease, such as cardiomyopathy Cardiomyopathy → vascular stasis within the heart.
    • Neoplasms often have abnormal vascular endothelial surfaces which can cause vascular stasis or activate the coagulation cascade.
  • Clot/embolus formation → occlusion of pulmonary vessels → ventilation perfusion mismatch → hypoxemia.
  • Arterial hypertension may result due to obstruction or reflex vasoconstriction. Vasoactive substances and/or vagal reflexes may cause bronchoconstriction and increased airway resistance.
  •  Pulmonary arterial aneurysms  -> rupture  -> extensive hemorrhage.
  •  Pulmonary abscess -> erosion into airways -> rupture -> hemorrhage.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed And VetMedResource.
  • Nagaraja T G & Chengappa M M (1998) Liver Abscesses in Feedlot Cattle: A Review. Departments of Animal Sciences and Diagnostic Medicine and Pathobiology 76 (1) pp 287-98 PubMed.
  • Gudmundson J, Radostits O & Doige C E (1978) Pulmonary thromboembolism in cattle due to thrombosis of the posterior vena cava associated with hepatic abscessation. The Canadian Veterinary Journal 19 (11) pp 304-9 PubMed.

Other sources of information

  •  Campbell J (2017) Vena Caval Thrombosis and Metastatic Pneumonia in Cattle. [online] Last accessed 29th November 2017. Available at: http://www.msdvetmanual.com.
  • Cunningham S M & Roderick K V Overview of Thrombosis, Embolism, and Aneurysm. MSD Veterinary Manual.


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