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strong predisposition for the heart disease; however, any cat or dog breed/mixed breed can develop HF. Genetic testing for some breeds is now available, such as in Doberman pinchers with DCM, boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), and Maine coon and ragdoll cats with HCM.10, 11, 12 See Table 2 for the typical signalments for dogs and cats for the common causes of HF. Breed Usually small breeds: Cavalier King Charles spaniels, toy/mini poodles, mini schnauzers, Pomeranians, Chihuahuas, Malteses, Bichons, Shi Tzus, Dachshunds, Cocker spaniels, Pekingeses, terriers, beagles, whippets; occasional large-breed dogs Usually larger breeds: Dobermans, boxers, giant breeds (Newfoundlands, Irish wolfhounds, Scottish deerhounds, Saint Bernards), retrievers, Portuguese water dogs, old English sheepdogs, cocker spaniels Usually mixed-breed cats; strong family associations in Maine coon, American and British shorthairs, Bengals, Sphinx, Himalayan, and Persian cats. Patients with emergent HF will typically exhibit the following clinical signs: cough (dog), dyspnea, lethargy, syncope or episodic weakness, abdominal distention (dog), and/or partial to complete anorexia. Most cats in HF do not present for cough or abdominal distention. An antecedent event or precipitating factor is not uncommon in congestive HF, especially in cats. Corticosteroid or intravenous (IV) fluid administration, a new tachyarrhythmia, chordae tendinae rupture, left atrial rupture, concurrent systemic disease, or a stressful event can precipitate HF.A careful physical examination will provide further evidence supporting or refuting the diagnosis of congestive HF. Table 3 provides a summary of typical physical examination findings in HF for canine MVD and DCM and feline HCM. Dogs with HF secondary to MVD typically have loud systolic murmurs and tachycardia.16, 17, 18 The absence of a murmur or a soft murmur (grade II or less) or the presence of a respiratory sinus arrhythmia in a small-breed dog with respiratory signs usually refutes the diagnosis of HF. Dogs with DCM, on the other hand, typically have soft or barely audible systolic murmurs and tachyarrhythmias.4, 5, 6 The presence of atrial fibrillation in a dog or cat with suspect HF is very suggestive of HF.The physical examination of a cat with HF can unfortunately be somewhat nonspecific.13 The heart rate can be fast, normal, or slow; up to 30% of cats may not have an obvious arrhythmia, murmur, or gallop on initial examination. Additionally, cats in HF are not uncommonly hypothermic.21 In some patients with significant respiratory distress, empiric therapy to stabilize patients is started even before any further diagnostic tests are performed if the signalment, history, and physical examination are suggestive of HF. Initial empiric therapy typically includes the administration of parenteral furosemide, oxygen, and sedation .Abbreviations: ACE, angiotensin-converting enzyme; APTT, activated partial thromboplastin time; BP, blood pressure; CRI, continuous rate infusions; HTCZ, hydrochlorothiazide; MAX, maximum; oint, ointment; SR, sustained release; SQ, subcutaneous; UF, unfractionated.Diagnostic imaging of the heart and lungs with thoracic radiography and echocardiography are helpful to confirm or refute a diagnosis of HF. A recent advancement in the diagnostic imaging in patients with respiratory distress is the increased use of focused echocardiography and thoracic ultrasound to improve the timely and accurate diagnosis of either left or right HF.22, 23 In the author’s practice, essentially every dog or cat with respiratory distress or collapse that presents emergently will have a thoracic focused assessment with sonography for trauma (TFAST) ultrasound or an abdominal FAST (AFAST) ultrasound performed by emergency department (ED) clinicians, usually before radiography. The TFAST and AFAST ultrasound and focused echocardiogram are performed with patients in sternal recumbency while receiving oxygen supplementation typically after a low dose of sedation. The examination is brief and minimally stressful to patients and is generally less stressful than performing a thoracic radiograph. A recent joint consensus statement by the American Society of Echocardiography and the American College of Emergency Physicians supported the use of the focused cardiac ultrasound examinations to expedite the diagnosis and management of life-threatening conditions in the ED setting.24 With some training, noncardiologist/nonradiologist veterinarians can achieve proficiency in identifying pleural and pericardial effusions and left atrial enlargement.25 Focused thoracic ultrasound is especially useful in cats with suspect HF because both the physical examination and radiographic findings in cats with HF are notoriously nonspecific.13, 26 Pleural effusion, a common manifestation of feline HF, obscures the cardiac silhouette, lungs, and vasculature radiographically (Fig. 1). With pleural effusion, the heart can be clearly visualized by ultrasound, allowing accurate assessments of chamber dimensions, specifically left atrial size (Fig. 2). The left atrium is most commonly indexed to the aorta in a right-sided, short-axis view at the base of the heart or a long-axis view. A left atrium/aorta ratio of 2.0 or greater is very suggestive of HF.27, 28 Normally, the left atrium/aorta ratio is less than 1.5 in cats and less than 1.3 in dogs.29, 30 The finding of pericardial effusion in cats with cardiomegaly and respiratory distress is also very suggestive of HF.31 In addition to rapidly identifying left atrial enlargement, pleural and pericardial effusion, assessments of right and left heart enlargement, left ventricular systolic dysfunction, and mitral valve thickening can be made with echocardiography (Fig. 3). The emergent focused ultrasound examination has become an extension of the physical examination and has been termed by some as the visual stethoscope.23 Although ultrasound is becoming more commonly available at EDs and general practices, many veterinary practitioners may not have ready access to this technology. 1Thoracic radiographs from a cat with congestive