Consequences of endocarditis in an adult cow with a ventricular septal defect

The clinical and pathological findings in a nine-year-old cow with a pre-existing ventricular septal defect and clinical signs of an increased tendency of haemorrhage and lameness, developing into recumbency, are described. On clinical examination, primary and secondary haemostasis defects were evident, along with hindlimb lameness with no indication of an underlying musculoskeletal or neurological cause. There was pyrexia of unknown origin. Clinical haematology revealed a thrombocytopenia. Because of worsening of clinical signs, the cow was euthanased. On postmortem examination, a subaortal perimembranous ventricular septal defect with a prolapsed right aortic cusp and a vegetative endocarditis were found, along with histological evidence of systemic microthrombi. The bacteraemia associated with the endocarditis along with the microthrombi resulted most likely in disseminated intra vascular coagulopathy. The lameness is thought to have been due to arterial thromboembolism in the distal limb following the release of a microthrombus from the endocarditis lesion.