# Point-of-Care Ultrasound in Veterinary Shock Assessment ## Key Takeaways - Point-of-care ultrasound (POCUS) is a rapid, non-invasive diagnostic modality that extends the physical examination for assessing veterinary shock patients, focusing on volume status, cardiac function, and free fluid detection. - Key POCUS assessments include caudal vena cava diameter and collapsibility to evaluate intravascular volume, left ventricular filling and systolic function to gauge cardiac output adequacy, and abdominal/thoracic free fluid detection to identify hemorrhage, uroabdomen, peritonitis, or effusions. - POCUS findings directly inform critical resuscitation decisions: a small, collapsible vena cava and hyperdynamic heart suggest hypovolemia requiring fluid resuscitation, while a dilated, hypocontractile heart with B-lines indicates cardiogenic shock necessitating inotropic support. - The RUSH (Rapid Ultrasound in Shock) protocol provides a structured approach, prioritizing cardiac and caudal vena cava assessments within minutes to guide immediate therapeutic interventions like fluid boluses, pericardiocentesis, or surgical consultation. - Limitations include operator skill dependency, patient body condition effects on image quality, and the qualitative nature of cardiac assessments; POCUS serves as a screening tool, not a replacement for comprehensive echocardiography or advanced diagnostics. --- Point-of-care ultrasound (POCUS) has become a standard component of the initial assessment of the shocked veterinary patient. This article provides a structured approach to using POCUS for volume status assessment, cardiac function evaluation, and free fluid detection in dogs, cats, and select other species. It is written for the practicing veterinarian who has basic ultrasound skills and seeks a reproducible framework for integrating POCUS into shock resuscitation protocols. The article answers how to acquire, interpret, and act upon focused ultrasound findings during the first minutes of patient management, and it distinguishes POCUS from comprehensive echocardiography and abdominal ultrasonography. The clinical question at the center of this article is direct: does this patient need fluid, does this patient need inotrope support, and does this patient need surgical intervention? POCUS addresses these questions faster than any other single diagnostic modality available to the general practitioner. Portable and handheld devices have expanded access to this capability across practice settings, and their use now extends the traditional physical examination in ways that were previously reserved for specialty hospitals [Martocchia et al., institutional publication on handheld ultrasound devices](https://pubmed.ncbi.nlm.nih.gov/36407770/). The democratization of ultrasound technology has been driven by affordability, improved image quality, and structured training programs that allow general practitioners to acquire and interpret focused studies reliably [Kaffas et al., institutional review on democratizing ultrasound diagnostics](https://pubmed.ncbi.nlm.nih.gov/38166185/). This article does not cover advanced echocardiographic measurements such as tissue Doppler imaging, strain analysis, or detailed valvular assessment. It focuses on the limited, goal-directed examinations that inform immediate resuscitation decisions. ## At a Glance | Parameter | What POCUS Assesses | Clinical Decision Impact | |---|---|---| | Caudal vena cava diameter and collapsibility | Intravascular volume status | Guides fluid bolus rate and total volume | | Left ventricular filling and systolic function | Cardiac output adequacy | Distinguishes fluid-responsive from fluid-intolerant shock | | Pericardial space | Pericardial effusion with tamponade | Triggers pericardiocentesis before further fluid therapy | | Abdominal free fluid | Hemorrhage, uroabdomen, peritonitis | Determines need for surgery or blood product transfusion | | Pleural space | Pleural effusion, pneumothorax | Guides thoracocentesis and ventilation strategy | | Lung sliding | Pneumothorax | Confirms or excludes life-threatening air leak | | B-lines | Pulmonary edema, interstitial syndrome | Contraindicates aggressive fluid administration | | Global subjective cardiac contractility | Myocardial function | Separates hypovolemic from cardiogenic shock | ## Physiologic Basis of POCUS in Shock Shock is a state of inadequate oxygen delivery to tissues. The cardiovascular system compensates through tachycardia, vasoconstriction, and redistribution of blood flow. These compensatory mechanisms alter vascular pressures and volumes in ways that ultrasound can detect. The venous system acts as a capacitance reservoir, and changes in venous diameter and collapsibility reflect changes in intravascular volume. The caudal vena cava in dogs and cats responds to hypovolemia with reduced diameter and increased respiratory collapse, although breed, body condition, and respiratory effort influence these measurements. The heart responds to preload changes according to the Frank-Starling relationship. A hypovolemic patient has a small, hypercontractile left ventricle with near-complete systolic obliteration of the chamber. A patient with cardiogenic shock has a dilated, poorly contractile ventricle with preserved or increased chamber dimensions. These two patterns are visually distinct on a focused right parasternal or left apical view, and they direct therapy in opposite directions. Free fluid accumulates in body cavities through hemorrhage, effusion, or rupture of hollow organs. Ultrasound detects as little as 5 to 10 mL of free fluid in the abdomen of a dog, far less than what is required for detection by palpation or radiography. The presence of free fluid in a shocked patient changes the diagnostic and therapeutic priority from volume resuscitation alone to source control and blood product administration [Hall and Drobatz, review of volume resuscitation in acute hemorrhage](https://pubmed.ncbi.nlm.nih.gov/34395568/). ## The POCUS Examination as an Extension of Physical Examination POCUS is not a replacement for the physical examination. It is an extension of it. The ultrasound probe functions as a visual stethoscope that allows the clinician to confirm or refute physical examination findings. A patient with muffled heart sounds and weak femoral pulses may have pericardial effusion, pleural effusion, or simply a thick thoracic wall. POCUS distinguishes these possibilities within seconds. The examination should be performed while other resuscitation measures proceed. One clinician can obtain images while another places intravenous catheters, administers oxygen, or prepares blood products. The ultrasound examination should not delay definitive therapy when the diagnosis is already clear from the physical examination. In patients with ambiguous findings, however, POCUS provides information that changes management in a substantial proportion of cases. ## Core POCUS Views for Shock Assessment ### Caudal Vena Cava Assessment The caudal vena cava is imaged from a right lateral or subxiphoid approach in dogs and cats. The vessel is identified dorsal to the liver, adjacent to the aorta. The diameter is measured in short axis or long axis, and the degree of inspiratory collapse is assessed. A small, collapsible cava suggests hypovolemia and fluid responsiveness. A distended, non-collapsible cava suggests volume overload, right-sided heart failure, or pericardial effusion. Measurement variability is significant. Respiratory effort, positive pressure ventilation, and patient positioning all affect caval dimensions. Serial measurements during resuscitation are more useful than a single static value. A cava that increases in diameter after a fluid bolus indicates that the patient tolerated the bolus and may benefit from additional volume. ### Focused Cardiac Assessment The focused cardiac examination uses the right parasternal long axis and short axis views. The clinician evaluates subjective contractility, chamber dimensions, and the presence of pericardial effusion. The left ventricular internal diameter in diastole and systole can be measured, but subjective assessment by an experienced operator is often sufficient for initial triage. A hypercontractile, small ventricle with a normal or increased heart rate is the classic POCUS finding in hypovolemic shock. A dilated, hypocontractile ventricle with poor fractional shortening suggests myocardial failure. Pericardial effusion appears as an anechoic space between the epicardium and pericardium. When tamponade is present, the right atrium and right ventricle collapse during diastole. ### Abdominal Free Fluid Assessment The abdominal examination uses the principles of the FAST (Focused Assessment with Sonography for Trauma) scan. The clinician images the hepatorenal space, splenorenal space, urinary bladder region, and the diaphragmatic-hepatic interface. Free fluid appears as anechoic or hypoechoic collections in dependent regions. The echogenicity of the fluid provides clues to its nature. Anechoic fluid may be transudate or urine. Heterogeneous, swirling fluid suggests hemorrhage. Fluid with echogenic debris may indicate peritonitis or exudate. The presence of free fluid in a shocked patient with a history of trauma strongly suggests hemorrhage. The presence of free fluid in a patient with a palpable bladder and rising creatinine suggests uroabdomen. In both scenarios, the ultrasound finding directs the clinician toward surgical consultation and appropriate fluid selection [AAHA and AAFP, fluid therapy guidelines for dogs and cats](https://www.aaha.org/resources/2024-aaha-fluid-therapy-guidelines-for-dogs-and-cats/). ### Thoracic Assessment The thoracic examination evaluates the pleural space, lung sliding, and the presence of B-lines. Pleural effusion appears as an anechoic collection dorsal to the lung. Lung sliding is the normal movement of the visceral pleura against the parietal pleura during respiration. Its absence suggests pneumothorax. B-lines are vertical hyperechoic artifacts that indicate interstitial or alveolar edema. Their presence in a shocked patient suggests cardiogenic pulmonary edema or volume overload. ## Integration with Resuscitation Protocols POCUS findings should be integrated with other monitoring parameters including heart rate, blood pressure, lactate, and shock index. The RECOVER initiative guidelines emphasize a structured approach to resuscitation that includes continuous reassessment of perfusion parameters [RECOVER Initiative, veterinary CPR guidelines](https://recoverinitiative.org/). POCUS provides a real-time, non-invasive method for this reassessment. A patient with a small, collapsible cava, hypercontractile heart, and no B-lines is a candidate for aggressive fluid resuscitation. A patient with a distended cava, poor contractility, and B-lines requires inotrope support and diuresis instead of additional volume. A patient with pericardial effusion requires drainage before any fluid therapy is administered. These decisions are made within minutes of probe placement. ## Limitations and Pitfalls POCUS has limitations. Image quality depends on operator skill, patient body condition, and the quality of the ultrasound machine. Handheld devices have more limited functions than high-end systems, and the operator must understand these limitations [Martocchia et al., institutional publication on handheld ultrasound devices](https://pubmed.ncbi.nlm.nih.gov/36407770/). Obesity, pneumothorax, and heavy respiratory effort degrade image quality. The caudal vena cava measurement is subject to significant variability, and a single measurement should not be used in isolation to make fluid decisions. POCUS cannot measure cardiac output directly. It provides a qualitative or semi-quantitative assessment of cardiac function. In patients with complex cardiac disease, a comprehensive echocardiogram by a specialist is required. POCUS is a screening tool that identifies patients who need further evaluation, not a substitute for that evaluation. The evidence base for veterinary POCUS is growing but remains less developed than in human medicine. Many recommendations are extrapolated from human studies or from experimental models of hemorrhage [Hall and Drobatz, review of volume resuscitation in acute hemorrhage](https://pubmed.ncbi.nlm.nih.gov/34395568/). Clinicians should interpret POCUS findings in the context of the complete clinical picture and should not rely on any single ultrasound measurement to the exclusion of other monitoring parameters. ## Structured POCUS Protocol for Shock Assessment The RUSH (Rapid Ultrasound in Shock) protocol, adapted from human emergency medicine, provides a systematic framework for the veterinary shock patient. It organizes image acquisition into three hemodynamic domains: the pump, the tank, and the pipes. This structure ensures that no component of the circulation is overlooked and that serial examinations remain comparable over time. ### Protocol Overview and Sequence Perform the examination in a fixed order to minimize patient handling and to build a coherent hemodynamic picture. A recommended sequence is: 1. **Focused cardiac assessment** (pump) 2. **Caudal vena cava assessment** (tank) 3. **Thoracic views** (pipes and tank) 4. **Abdominal free fluid survey** (tank) 5. **Femoral venous and arterial assessment** (pipes) Each step should take no more than 60 to 90 seconds in a stable patient. In a crashing patient, obtain the cardiac view and caudal vena cava first, as these two views carry the highest immediate therapeutic consequence. ### Image Acquisition Steps and Interpretation Criteria #### Step 1: Focused Cardiac Assessment Use the right parasternal long-axis four-chamber view as the primary window. Assess the following in sequence: | Parameter | Acquisition | Interpretation | |---|---|---| | Left ventricular systolic function | Subjective visual assessment of endocardial excursion and myocardial thickening | Hyperdynamic (near-obliteration of the chamber) suggests hypovolemia or early septic shock. Hypodynamic suggests myocardial failure or end-stage shock. | | Left ventricular chamber size | Compare diastolic diameter to the left atrial diameter | Small chamber with hyperdynamic walls supports volume deficit. Dilated chamber with poor contractility supports cardiogenic shock. | | Pericardial space | Scan the entire cardiac silhouette | Anechoic circumferential fluid with right atrial collapse indicates tamponade physiology. | | Right heart size | Assess right ventricular to left ventricular ratio | Acute right heart dilation suggests pulmonary hypertension or massive pulmonary thromboembolism. | Do not attempt detailed valvular assessment or spectral Doppler interrogation during the shock examination. These measurements require advanced echocardiography and prolong the scan without changing immediate resuscitation decisions. #### Step 2: Caudal Vena Cava Assessment Image the caudal vena cava in a longitudinal plane at the level of the porta hepatis using a subxiphoid or right lateral approach. Measure the maximum diameter during expiration and assess the degree of respiratory variation. A collapsed caudal vena cava with a diameter of less than 3 mm per 10 kg body weight and complete inspiratory collapse supports hypovolemia. A distended, non-collapsing caudal vena cava with a diameter greater than 10 mm per 10 kg suggests volume overload, right-sided congestive heart failure, or pericardial effusion. Serial measurements are more informative than a single reading, particularly when tracking response to fluid therapy. #### Step 3: Thoracic Views Scan the dorsal and ventral thorax in both hemithoraces. Identify the following: - **B-lines**: Hyperechoic vertical artifacts arising from the pleural line that extend to the far field indicate interstitial or alveolar edema. Three or more B-lines per intercostal space in multiple spaces support pulmonary edema or non-cardiogenic causes such as pneumonia or contusions. - **A-lines**: Horizontal reverberation artifacts indicate normal aeration or pneumothorax. The presence of A-lines with absent lung sliding and a lung point confirms pneumothorax. - **Pleural effusion**: Anechoic or complex fluid dorsal to the lung with atelectasis of the underlying lung lobe. This finding supports hemorrhage, chylothorax, or transudative effusions depending on the clinical context. #### Step 4: Abdominal Free Fluid Survey Use the four-quadrant approach: subxiphoid, right cranial abdomen, left cranial abdomen, and caudal abdomen. The hepatorenal and splenorenal recesses are the most sensitive locations for small-volume free fluid in dogs. In cats, the dependent portions of the abdomen and the region between the bladder and colon are preferred. Anechoic fluid in a trauma patient supports hemorrhage. Complex or echogenic fluid with swirling motion suggests active bleeding or a septic effusion. The absence of free fluid does not exclude hemorrhage, particularly in the first 15 to 30 minutes after injury, as the rate of accumulation may lag behind the clinical picture. #### Step 5: Femoral Vessel Assessment Assess the femoral artery and vein in a transverse plane at the inguinal fold. A spontaneously collapsing femoral vein with respiratory variation supports hypovolemia. A distended, non-collapsing vein with a plethoric femoral artery supports volume overload or right heart failure. This view is particularly useful in cats, where caudal vena cava imaging can be technically challenging. ### Decision Points and What Changes Them The POCUS findings must be interpreted within the context of the patient's perfusion parameters, lactate trend, and blood pressure. The following framework guides resuscitation decisions: | POCUS Pattern | Interpretation | Initial Action | |---|---|---| | Hyperdynamic heart, small chamber, collapsed caudal vena cava | Hypovolemic or distributive shock | Fluid challenge with crystalloid or colloid, reassess after each bolus | | Hypodynamic heart, dilated chamber, distended caudal vena cava | Cardiogenic or obstructive shock | Restrict fluids, consider inotrope or vasopressor support | | Pericardial effusion with right atrial collapse | Tamponade | Pericardiocentesis before fluid administration | | B-lines with hyperdynamic heart | Non-cardiogenic pulmonary edema with hypovolemia | Judicious fluid therapy, address underlying cause | | B-lines with hypodynamic heart | Cardiogenic pulmonary edema | Diuretic therapy, no fluid bolus | Reassess the caudal vena cava and cardiac contractility after each fluid bolus. A patient who remains hypovolemic on imaging after 20 to 30 mL/kg of crystalloid requires reconsideration of the fluid choice, the addition of vasopressors, or hemorrhage control. The [RECOVER initiative guidelines](https://recoverinitiative.org/) emphasize that resuscitation endpoints should be reassessed continuously instead of assumed from a single examination. ### Equipment and Consumable Choices Handheld ultrasound devices are now sufficiently capable for focused shock assessment in most clinical settings. Their accessibility and ease of use support their role as an extension of the physical examination, as described in the [review of handheld ultrasound devices in point-of-care applications](https://pubmed.ncbi.nlm.nih.gov/36407770/). However, these devices typically have limited Doppler capability and lower image resolution than cart-based systems, which may affect the quality of cardiac assessment in small patients. Select a probe based on patient size: - **Microconvex or phased array (5 to 8 MHz)**: Preferred for cardiac and thoracic views in dogs and cats. - **Linear (7 to 15 MHz)**: Suitable for caudal vena cava, lung, and abdominal free fluid assessment in small patients. - **Curvilinear (3 to 6 MHz)**: Useful for deep abdominal views in large-breed dogs. Use a high-frequency linear probe for lung assessment in cats and small dogs, as the pleural line is superficial and B-line resolution is superior. The [advances in ultrasound technology and training](https://pubmed.ncbi.nlm.nih.gov/38166185/) have reduced the cost and size barriers that previously limited POCUS adoption in general practice. ### Documentation and Serial Monitoring Document each POCUS examination with a standardized reporting template that includes: - Patient signalment and presenting complaint - Indication for the examination - Probe and preset used - Each view obtained with a description of findings - A global interpretation (hypovolemic, cardiogenic, obstructive, or distributive pattern) - The clinical action taken - Time of examination and operator name Store representative cine clips or still images for each view. These images allow comparison with subsequent examinations and provide a medicolegal record of the assessment. The [AAHA/AAFP fluid therapy guidelines](https://www.aaha.org/resources/2024-aaha-fluid-therapy-guidelines-for-dogs-and-cats/) recommend that monitoring parameters, including imaging findings, be recorded at each reassessment interval. Repeat the POCUS examination at defined intervals during resuscitation: immediately after each fluid bolus, at 30 to 60 minutes after the initial assessment, and whenever the patient's perfusion status changes. Serial examinations detect trends that a single scan cannot, particularly the transition from hypovolemia to volume overload in patients receiving aggressive fluid therapy. ### Species and Setting Considerations The correct POCUS approach varies with species, patient size, and clinical setting. In cats, the cardiac views are more challenging due to the narrow intercostal spaces and the tendency for the heart to lie more vertically. Use a microconvex probe and approach from the sternal recumbency position to improve acoustic windows. Cats also develop pleural effusion more readily than dogs in response to volume overload, so thoracic views should be obtained early in the resuscitation sequence. In large-breed dogs, the caudal vena cava may be difficult to visualize with handheld devices due to depth penetration limits. The femoral vein view provides a reliable alternative. In horses and ruminants, the thoracic and abdominal anatomy differs substantially, and the RUSH protocol requires modification. The [MSD Veterinary Manual](https://www.msdvetmanual.com/) provides species-specific guidance on normal ultrasonographic anatomy and common artifacts that apply to these patients. In resource-limited settings where handheld devices are the only available imaging modality, the examination remains valuable but must be interpreted with awareness of the device's limitations. The [democratization of ultrasound diagnostics](https://pubmed.ncbi.nlm.nih.gov/38166185/) has expanded access to POCUS, but it has not eliminated the need for rigorous training and quality assurance. Operators should document their level of confidence in each view and flag examinations where image quality was suboptimal. ## Recognized Complications and Failure Modes The principal complications of POCUS in shock assessment are misclassification of volume status, missed free fluid, and misinterpretation of cardiac motion. Each has a characteriztic early warning sign. **Misclassification of volume status.** Caudal vena cava diameter and collapsibility index are load-dependent but also affected by right-sided heart disease, pericardial effusion, and intrathoracic pressure changes. A patient with pericardial effusion may present with a distended, poorly collapsible cava despite true hypovolemia. Detect this early by always evaluating the heart before assigning volume status. If the cava appears plethoric but the patient is tachycardic with pale membranes, perform a focused cardiac assessment before committing to a fluid plan. **Missed free fluid.** Small-volume effusions are easily overlooked in the diaphragmatico-hepatic view when the patient is in dorsal recumbency and the transducer is angled too steeply. The discriminating check is to sweep the transducer slowly from the xiphoid toward the diaphragm and to compare the right and left sides of the abdomen. Anechoic crescentic regions between viscera that do not conform to organ boundaries represent fluid. In obese patients, pre-peritoneal fat can mimic fluid, fat is hyperechoic and compressible, whereas free fluid is anechoic and non-compressible. **Cardiac motion misinterpretation.** Pericardial fat and pleural effusion can both obscure myocardial motion. The novice may interpret a hypokinetic ventricle as cardiac arrest or, conversely, misinterpret respiratory artefact as cardiac activity. The corrective action is to use the subxiphoid or right parasternal long-axis view, reduce depth, and observe the myocardium in real time over several cardiac cycles. Color Doppler, where available, can confirm flow but is not required for the basic assessment. | Observation | Likely cause | Discriminating check | |---|---|---| | Distended cava, collapsed patient | Pericardial effusion or right heart failure | Focused cardiac view for pericardial fluid and chamber size | | Anechoic region near diaphragm | Free fluid versus fat | Compare with contralateral side, assess compressibility | | Apparent cardiac standstill | Pericardial fat, pleural effusion, or artefact | Adjust depth and gain, observe over multiple cycles | | Poor cava visualization | Obesity, gas, or incorrect transducer angle | Reposition patient or use hepatic window | | Rapid change in cava diameter between scans | Normal respiratory variation versus true change | Standardize the respiratory phase and patient position | ## Common Operator Errors and Corrections The most frequent error among less experienced operators is rushing the examination. A complete shock POCUS study should take less than five minutes, but only when each view is acquired deliberately. Students often move the transducer too quickly through the abdominal windows and miss a small volume of fluid. The corrective action is to adopt a fixed sequence, for example right thoracic, subxiphoid cardiac, diaphragmatico-hepatic, spleno-renal, cysto-colic, and repeat each window twice before advancing. Gain and depth settings are a second common source of error. Excessive gain produces a hyperechoic image that obscures anechoic fluid. Inadequate depth truncates the cava or the bladder. Set depth to include the target structure with a margin, then adjust gain until fluid appears black and soft tissue appears mid-grey. The handheld devices increasingly used in practice have limited controls, but depth and gain adjustment remains available on most models and should be used deliberately [Martocchia et al., handheld ultrasound device review](https://pubmed.ncbi.nlm.nih.gov/36407770/). A third error is failure to integrate POCUS findings with the physical examination. The cava may appear collapsed in a patient who is actually volume-overloaded due to high intrathoracic pressure from positive-pressure ventilation. Ultrasound findings must be interpreted alongside heart rate, pulse quality, mucous membrane color, lactate, and blood pressure. The democratisation of ultrasound technology has made these devices widely available, but the interpretive framework remains the clinician's responsibility [Kaffas et al., democratizing ultrasound diagnostics](https://pubmed.ncbi.nlm.nih.gov/38166185/). ## Evidence Limitations and Areas of Expert Disagreement The veterinary evidence base for POCUS in shock is largely extrapolated from human medicine and from experimental canine models of hemorrhage. Clinical studies in dogs and cats are limited by small sample sizes, heterogeneous patient populations, and lack of standardized outcome measures. The physiologic response to blood loss in dogs is well characterized, with increased heart rate, decreased systolic pressure, and increased shock index, but the translation of these findings to clinical POCUS thresholds is incomplete [Hall and Drobatz, volume resuscitation review](https://pubmed.ncbi.nlm.nih.gov/34395568/). Expert opinion differs on several points. The optimal caudal vena cava collapsibility threshold for predicting fluid responsiveness has not been established in veterinary patients, and some authorities question whether it predicts responsiveness at all in spontaneously breathing animals. There is also disagreement about the role of serial lung ultrasound in guiding fluid therapy, with some clinicians advocating routine thoracic views and others reserving them for patients with suspected pulmonary pathology. The RECOVER guidelines provide consensus recommendations for CPR and post-arrest care, but they do not address POCUS-guided fluid management in detail [RECOVER Initiative guidelines](https://recoverinitiative.org/). ## Referral, Consultation, and Reporting Referral for advanced echocardiography is indicated when the focused cardiac assessment reveals structural abnormalities, significant pericardial effusion, or suspected congenital disease. The focused examination is designed to answer a binary question, is the heart contracting adequately and is there pericardial fluid, and it cannot replace a complete echocardiogram. Similarly, suspected pulmonary thromboembolism or aortic thrombosis warrants specialist imaging and laboratory evaluation. Laboratory involvement is appropriate when POCUS findings suggest a specific aetiology. A patient with abdominal free fluid and a low packed cell volume requires coagulation testing and cross-matching. A patient with a distended cava and respiratory distress may need cardiac biomarkers and thoracic imaging beyond the POCUS examination. Regulatory reporting obligations vary by jurisdiction and species. In production animal settings, findings that suggest reportable disease, such as pericarditis associated with a notifiable pathogen, may trigger reporting under relevant animal health standards [WOAH terrestrial animal health code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). Practitioners should be familiar with the requirements of their local veterinary authority and the practice standards published by their professional body [AVMA practice resources](https://www.avma.org/resources-tools). ## Frequently Asked Questions ### How do I choose between a handheld ultrasound device and a cart-based system for shock assessment in my practice? Handheld devices now support focused shock assessment in most clinical settings, though their functions remain more limited than high-end systems [according to the review of handheld ultrasound devices in clinical practice](https://pubmed.ncbi.nlm.nih.gov/36407770/). Choose a handheld unit when portability, rapid deployment, and serial reassessment during resuscitation are priorities. Select a cart-based system when you need advanced imaging modes, better image quality for equivocal studies, or simultaneous use by multiple team members. Image quality differences matter most for subtle cardiac assessment and lung evaluation. If you already own a cart-based system, no immediate purchase is necessary. The limiting factor is operator experience, not machine cost, so direct training investment toward whichever device you will actually use at the bedside. ### What should I do when I cannot obtain an adequate POCUS image during shock assessment? Stop attempting to optimize the image and return to physical examination parameters. Heart rate, pulse quality, mucous membrane color, capillary refill time, lactate, and blood pressure provide the hemodynamic information you need while you troubleshoot. Reposition the patient, change the probe, or adjust gain settings once, then proceed. In obese patients or those with severe pneumothorax, acoustic windows may remain poor despite best efforts. Document the limitation and state which structures could not be assessed. The physiologic response to blood loss, including increased heart rate, decreased systolic blood pressure, and increased shock index, remains measurable without ultrasound [as described in the review of volume resuscitation in acutely hemorrhaging patients](https://pubmed.ncbi.nlm.nih.gov/34395568/). POCUS augments the examination, it does not replace it. ### How does POCUS shock assessment differ between dogs and cats? Cats require smaller probe footprints and higher frequency transducers for adequate cardiac and vascular windows. Their heart rates are higher and myocardial contractility assessment relies more on subjective visual evaluation than on fractional shortening calculations. Caudal vena cava assessment is technically more challenging in cats due to respiratory variation and smaller vessel diameter. Cats with pulmonary pathology frequently show diffuse B-lines that are less specific for cardiogenic edema than in dogs. Abdominal free fluid assessment follows the same principles, but smaller volumes are clinically significant in cats. The RECOVER guidelines provide species-specific CPR and post-arrest recommendations that incorporate these differences [in the RECOVER veterinary CPR guidelines](https://recoverinitiative.org/). Adapt your threshold for intervention accordingly. ### What documentation is required for POCUS findings in the medical record? Record the indication, the views obtained, the image quality, and your interpretation for each structure assessed. Store representative clips or still images when your device supports export, and label them with patient identification and date. Note whether findings changed your diagnostic or therapeutic plan. If images cannot be archived, document that a POCUS examination was performed and describe the findings in text. Include the operator name and credentials. Serial examinations should be recorded with timestamps so trends in caval diameter, cardiac function, or free fluid volume are traceable. This documentation supports continuity of care and provides a defensible record if questions arise later. Professional practice standards for medical records apply to ultrasound findings as they do to any diagnostic test [per AVMA practice resources](https://www.avma.org/resources-tools). ### How do I explain POCUS findings to an owner during a shock resuscitation? Use plain language that connects the ultrasound finding to the treatment decision. State what you saw, what it means for perfusion, and what you will do next. For example, explain that the large vein entering the heart appears small, which suggests low blood volume, and that fluids will be given to restore it. If the heart is contracting weakly, explain that medications to support heart function may be needed. Avoid giving a definitive prognosis based on a single image. Owners in an emergency setting need to understand that POCUS is one part of a continuous assessment and that findings can change rapidly. Reassure them that the examination is non-invasive and painless. Offer to show them the images if they wish, as visual information often helps owners grasp complex concepts. ### How should I handle POCUS findings that conflict with other clinical data? Treat discordance as a prompt to re-examine, not as a reason to discard either data set. A small caudal vena cava with normal blood pressure may indicate compensated shock or simply a dehydrated but stable patient. Hyperdynamic cardiac function with normal lactate suggests early or mild hypoperfusion. Recheck the ultrasound study for technical errors, then reassess physical parameters. If the conflict persists, consider an alternative diagnosis or a mixed shock state. Serial monitoring often resolves the ambiguity: trends matter more than single values. When uncertainty remains, consult a colleague with advanced ultrasound training or pursue additional diagnostics. Document the discrepancy and your reasoning in the record. The democratization of ultrasound has increased access to these tools, but interpretation still requires clinical integration [as discussed in the review of ultrasound democratization in human and veterinary medicine](https://pubmed.ncbi.nlm.nih.gov/38166185/). ## Related Clinical & Scientific Guides * [Toxicology in Emergency Practice: Common Poisons and Diagnostic Approach](/knowledge/veterinary-medicine/emergency-critical-care/toxicology-emergency-practice-common-poisons-diagnostic-approach) * [Veterinary Cardiopulmonary Resuscitation: Post-Cardiac Arrest Care](/knowledge/veterinary-medicine/emergency-critical-care/veterinary-cardiopulmonary-resuscitation-post-cardiac-arrest-care) * [Fluid Therapy Guidelines for Dogs and Cats: A Practical Update](/knowledge/veterinary-medicine/emergency-critical-care/fluid-therapy-guidelines-dogs-cats-practical-update) ## References and Further Reading - [The Point-of-Care Ultrasound (POCUS) by the Handheld Ultrasound Devices (HUDs) in the COVID-19 Scenario: a Review of the Literature.](https://pubmed.ncbi.nlm.nih.gov/36407770/). 2023. - [Critical Advances for Democratizing Ultrasound Diagnostics in Human and Veterinary Medicine.](https://pubmed.ncbi.nlm.nih.gov/38166185/). 2024. - [Volume Resuscitation in the Acutely Hemorrhaging Patient: Historic Use to Current Applications.](https://pubmed.ncbi.nlm.nih.gov/34395568/). 2021. - [RECOVER Initiative Veterinary CPR Guidelines](https://recoverinitiative.org/). Veterinary Emergency and Critical Care Society. - [AAHA/AAFP Fluid Therapy Guidelines for Dogs and Cats](https://www.aaha.org/resources/2024-aaha-fluid-therapy-guidelines-for-dogs-and-cats/). AAHA. - [MSD Veterinary Manual, Professional Edition](https://www.msdvetmanual.com/). MSD Veterinary Manual. - [American Veterinary Medical Association Practice Resources](https://www.avma.org/resources-tools). American Veterinary Medical Association. - [WOAH Terrestrial Animal Health Code](https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-code-online-access/). WOAH. ## Related Articles - [Capnography in Veterinary Emergency and Critical Care](/knowledge/veterinary-medicine/emergency-critical-care/capnography-veterinary-emergency-critical-care) - [Veterinary ICU Monitoring: Coagulation Assessment](/knowledge/veterinary-medicine/emergency-critical-care/veterinary-icu-monitoring-coagulation-assessment) - [Veterinary Shock: Fluid Resuscitation Strategies](/knowledge/veterinary-medicine/emergency-critical-care/veterinary-shock-fluid-resuscitation-strategies) - [Veterinary Electrocardiography in Emergency and Critical Care](/knowledge/veterinary-medicine/emergency-critical-care/veterinary-electrocardiography-emergency-critical-care) - [Veterinary ICU Monitoring: Pain Assessment and Management](/knowledge/veterinary-medicine/emergency-critical-care/veterinary-icu-monitoring-pain-assessment-management) > This article is educational professional reference material for veterinary audiences. It is not a substitute for veterinary diagnosis, individual clinical judgment, current product labeling, or applicable regulatory requirements.