TFAST Ultrasound: A Quick-Reference Guide for the Dyspnoeic or Collapsed Patient
- Echo Vet Solutions
- Aug 1
- 3 min read
A dyspnoeic cat arrives unannounced. Or a dog is rushed in after being hit by a car. In both cases, you've got minutes, not an hour, to work out what's filling the chest — and whether it's fluid, air, or a failing heart. This is exactly the gap TFAST ultrasound was designed to close.
TFAST stands for Thoracic Focused Assessment with Sonography for Trauma. First described in dogs back in 2004, it's since become standard practice well beyond trauma cases — any breathless, collapsed, or shocky patient is a candidate. It isn't a diagnosis. It's a rapid rule-in tool that tells you, in under five minutes, whether you're dealing with free pleural fluid, air in the pleural space, or fluid around the heart — before you commit to sedation, radiographs, or a referral.
The three views
-Chest tube site (CTS) — right and left, at the highest point of the thorax (around the 4th–6th intercostal space, dorsal third of the chest wall). Here you're looking for the glide sign: the visceral and parietal pleura sliding against each other with respiration, seen as a shimmering line. Lose the glide sign and you're looking at possible pneumothorax — air rises to the highest point, so scanning dorsally with the patient sternal or standing (not on their back) gives you the best chance of picking it up.
-Pericardial site (PCS) — right and left parasternal, essentially the same windows you'd use for a focused cardiac view. Here you're checking for an anechoic space around the heart — pericardial effusion — and, in more subtle cases, for signs of cardiac tamponade such as right atrial or ventricular collapse.
-Diaphragmatico-hepatic (DH) view — the same window used in AFAST, just angled to look cranial to the diaphragm rather than caudal. Free pleural fluid shows up as an anechoic triangle between the diaphragm, liver, and lung margin.
A common pitfall
An absent glide sign at one site tells you pneumothorax is possible at that site — it doesn't rule pneumothorax out elsewhere, and a present glide sign at one window doesn't guarantee air isn't trapped somewhere else in the chest. TFAST is a screening tool, not a whole-chest survey; interpret each view in the context of the whole patient, not in isolation. It's also worth remembering that forcing a dyspnoeic patient into lateral or dorsal recumbency to "get a better view" can tip a stable patient into a crisis — sternal or standing scanning is safer and, for these views, entirely adequate.
Who should be doing this
The screening views themselves are learnable by veterinary nurses as part of triage — recognising a clearly positive or clearly negative glide sign, or an obvious pocket of pericardial fluid, doesn't require years of training, just structured, hands-on practice. Where it gets more nuanced is integrating those findings into a treatment plan: deciding whether that pericardial effusion needs a pericardiocentesis tonight, or whether pleural fluid needs draining before anaesthesia is safe. That's the level our Emergency Ultrasound Course is built around, and if you want your nursing team confident and consistent on the triage scanning itself, our Ultrasound for Veterinary Nurses course covers exactly that.
TFAST won't replace a full echocardiogram or CT, but it will change what you do in the first five minutes — and in an emergency, that's often the five minutes that matter most.
Want this protocol to feel second nature on your own machine, with your own cases? Take a look at our in-practice CPD courses — bespoke, hands-on training delivered wherever you work.
