QUARTERLY BEAT / JULY 2025
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IMAGING THE DYSPNEIC CAT: A CASE SERIES
Marc Seitz, DVM, DACVR, DABVP (Canine and Feline Practice)
In this VETgirl Webinar “Imaging the Dyspneic Cat: A Case Series,” Dr. Marc Seitz, DVM, DACVR, DABVP (Canine and Feline Practice) breaks down the approach one of the most stressful ER presentations: the acutely dyspneic cat. From when to pause for stabilization to how to get the most out of your thoracic rads and POCUS findings, Dr. Marc Seitz, walks you through the key imaging clues that help differentiate heart failure, pleural effusion, airway disease, and neoplasia. If you’ve ever questioned whether it’s safe to shoot rads, when to tap the chest, or what to make of all those lung rockets, read on! Missed the webinar? Catch the replay HERE or scroll down for the highlights! depth is inappropriate. Alveolar-interstitial disease caused by edema or cellular infiltrates will change the repetition artifact (A-lines) of normal lung tissue to a ring-down artifact (termed B-lines). In private practice, the colloquial term “lung rockets” has also been used for ring-down artifact occurring with alveolar-interstitial disease. This term should not be confused with a similar space-themed term, “comet-tail artifact,” which occurs when the ultrasound strikes a highly reflective structure such as a needle or catheter. Unfortunately, the presence of ring-down artifact is incredibly non- specific and occurs with any disease capable of producing an unstructured interstitial or alveolar pulmonary pattern. Examples include, but are not limited to, cardiogenic pulmonary edema, non-cardiogenic pulmonary edema, infectious etiologies, neoplasia, hemorrhage, acute lung injury, and atelectasis. When combined with the history, signalment, and physical exam findings, results from a POCUS exam can help localize the cause of dyspnea as well as guide stabilization therapies and further diagnostics. Thoracic POCUS ultrasound findings can also be used to complement radiographic findings. Specific examples include confirming the presence of pleural effusion, guiding diagnostic or therapeutic thoracocentesis, and differentiating cardiogenic pulmonary edema secondary to left sided heart failure from airway disease like asthma. Although thoracic POCUS findings are rapid and quite useful, they are never a replacement for thoracic radiographs as they only evaluate the pleural space, heart, and surface of the lungs. 1 Large lesions or regions of abnormal lung can easily be missed by ultrasound due
Associate Clinical Professor of Diagnostic Imaging College of Veterinary Medicine, Department of Clinical Sciences Mississippi State University, Mississippi State, MS, USA INTRODUCTION Cats are stable until they aren’t. Dyspnea of any cause is a common reason cats present acutely unstable. Imaging is a vital part of diagnosing the underlying cause of dyspnea. However, triaging and stabilizing patients is imperative prior to pursuing imaging studies as stress and non-sternal recumbency can alter ventilation, disrupting the delicate balance that comes with compensation for hypoxemia. This is especially true for pleural space disease. All patients benefit from remaining in sternal recumbency and some form of oxygen therapy. Many patients benefit from a mild sedative (e.g., butorphanol) or an anxiolytic drug. Other stabilization therapies should be tailored to triage exam findings. For example, bronchodilators can be given to patients with suspected asthma. A diuretic like furosemide can be given to patients with suspected heart failure. If pleural effusion is present, thoracocentesis should be performed prior to radiographs as it will improve evaluation of the pulmonary parenchyma. Thoracic point-of-care ultrasound (POCUS) is one imaging technique that can be safely performed after the initial triage exam and while patient stabilization is being performed. Thoracic POCUS is easily performed with the patient standing or in sternal recumbency. A detailed description of various techniques and interpretation is beyond the scope of this article and well-reviewed elsewhere (references below). However, POCUS is invaluable at rapidly diagnosing pleural effusion, pericardial effusion, and alveolar-interstitial disease. Pleural and pericardial effusion are both usually anechoic. The presence of echogenic debris within effusion increases suspicion that the fluid is exudative or hemorrhagic. However, a lack of echogenic fluid does not rule out these conditions. Pericardial effusion becomes more difficult to diagnose when pleural effusion is also present due to decreased visualization of the pericardial sac from edge shadowing and anisotropy. Additionally, severe cardiac chamber enlargement can sometimes artifactually mimic pericardial effusion, especially if machine
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