LAUSR

“Despite several fluid boluses and vasopressor support, mean arterial pressure hovered around 50mmHg, lactate levels increased and ScvO2 remained at 55%. The patient was in septic shock. Should inotropic drugs be started? Physiologic steroids? Cardiac ultrasound ...?” To many emergency and critical care (ECC) physicians, this is a daily routine. Few imagine this patient being a dog or cat. However, small animal intensive care units (ICUs) exist. Human and veterinary emergency and critical care (HECC and VECC) share attitudes and values, providing opportunities for the development of both professions. Advancements in ECC rely on animal experiments [1, 2], particularly rodent models due to large litter sizes, short generation time, relatively low maintenance requirements, and the ease of introducing genetic modification in these species [2]. These characteristics make translational medicine from rodent-based models to humans fundamental to understanding the pathologic mechanisms behind many human ECC conditions [3]. However, the translation of rodent-based research to clinical practice has been questioned for several reasons, including the use of young, single-sex, genetically modified, healthy (or limited comorbidities), inbred subjects, kept in homogeneous, regulated environments [1–3]. Recent studies have also suggested that rodents and humans may differ more in their genetic response to acute injury than originally believed [2, 3]. Sheep, pigs, rabbits, and non-human primates have also been used in ECC research [4]. Proposed advantages of these species include their larger size, allowing advanced monitoring similar to what exists in human ICUs, ability to create predefined comorbidities, and the fact these species have similar hemodynamic and cardiovascular responses to humans. However, large animal models are relatively expensive, have limited immunologic markers available in some species (e.g., sheep), and share similar limitations to rodent models (e.g., single-sex experiments) [4]. Although valuable in preclinical research, a gap still exists between animal models and the clinical human ECC setting [1–3, 5]. In our opinion, this gap can be partially filled by studying companion animals [5] as a model for ECC human diseases, for several reasons. First, most HECC scenarios (e.g., sepsis) also exist in companion animals, with similar pathophysiologic mechanisms. The similarity is especially remarkable in pediatric patients, which are less afflicted by lifestyle choices like smoking and alcoholism (not observed in companion animals) and complications of chronic diseases (e.g., diabetic nephropathy). Dogs and cats, having shorter life spans, rarely manifest such complications. Second, companion animals have complex genetic, environmental, and physiological variation, which in many cases are similar or even shared with humans [5, 6]. Third, current ECC management of critically ill dogs and cats is similar to humans. Veterinarians have access to advanced diagnostics including molecular testing and advanced imaging. In VECC, capnography, invasive hemodynamic, and ICP monitoring are performed, and sidestream dark-field imaging and tissue oxygen saturation have been used clinically. Advanced therapeutic modalities in VECC include ventilation, interventional radiology, advanced hemodynamic support, transfusion therapy, continuous renal replacement therapy, and cardiac bypass, among others. Fourth, current challenges faced by VECC are similar to those in HECC: specific markers of sepsis, synthetic colloids in septic patients, identifying volume-responsive