Feline Ultrasound Case Study

Question

A 5 year old domestic short hair cat presents with a 24 hour history of lethargy, anorexia and severe tachypnoea.

Following a physical examination and after initial stabilisation in an oxygen chamber, basic thoracic ultrasound and echocardiography views are obtained.

1. What are the main ultrasonographic findings on the image below?
2. What is your differential diagnosis at this stage?

Answer

The first scan shows loss of the normal lung appearance (soft tissue-air interface) which is substituted by a diffuse hypoechogenicity (fluid) and floating pleural tissue. The diagnosis is severe pleural effusion.

Differential diagnosis includes a pure transudate (e.g. due to hypoalbuminaemia), a modified transudate (e.g. due to neoplasia, diaphragmatic hernia or congestive heart failure), a pyothorax (due to bacterial infection), a non-septic exudate (e.g. FIP), a chylothorax (e.g. due to cardiac disease, neoplasia or idiopathic) and a haemothorax (due to trauma, neoplasia or coagulopathy).

The second scan is a right parasternal short axis view at the level of the aorta and the left atrium. There is evidence of severe left atrial enlargement with an Aorta/Left atrium ratio markedly above 1.6.

There is evidence of left sided heart disease leading to congestive heart failure (pleural effusion). The most likely disease for a patient of this age is a primary cardiomyopathy such as hypertrophic cardiomyopathy or restrictive cardiomyopathy. Congenital cardiac disease or secondary cardiomyopathies (e.g. hyperthyroidism) are much less likely.

A full echocardiographic examination (after thoracocentesis) should be carried out as the next step. This should be followed by medical therapy for congestive heart failure.