Comprehensive Cardiorespiratory Examination and Auscultation in Dogs and Cats

A systematic cardiorespiratory examination remains one of the most powerful diagnostic tools in small animal practice. Inspection, palpation, percussion, and auscultation each provide critical information regarding cardiac and respiratory function. When performed methodically, this examination often allows differentiation between cardiac and non-cardiac causes of clinical signs and guides appropriate diagnostic and therapeutic decisions¹. 

Evaluation of Mucous Membranes and Perfusion 

Assessment of mucous membrane color should be performed at both oral and caudal sites, along with evaluation of capillary refill time. A refill time exceeding two seconds suggests peripheral vasoconstriction secondary to decreased cardiac output¹. 

Pale mucous membranes indicate anemia, shock, or reduced perfusion, while hyperemic membranes may reflect venous congestion associated with right-sided heart failure or polycythemia due to right-to-left shunting. Cyanosis indicates hypoxemia and may be central or peripheral. Differential cyanosis can suggest congenital shunts or distal arterial obstruction, such as thromboembolism in cats¹. 

Respiratory Rate and Breathing Patterns 

Normal respiratory rate in dogs and cats is less than 30 breaths per minute. Persistent tachypnea is often an early indicator of pulmonary edema or pleural effusion and may be identified by owners during home monitoring². 

Dyspnea, characterized by increased effort and depth of breathing, reflects significant respiratory or cardiac disease and requires rapid intervention. Paradoxical breathing, in which the chest wall moves inward during inspiration, indicates severe pathology and diaphragmatic dysfunction and demands immediate attention¹. 

Orthopnea, characterized by head and neck extension and abducted elbows, reflects an attempt to reduce work of breathing. Animals displaying this posture often have minimal respiratory reserve¹. 

Jugular Vein Assessment 

Examination of the jugular veins provides insight into right-sided cardiac function. Jugular distension and abnormal pulsations extending toward the mandible indicate elevated central venous pressure and are commonly associated with right-sided heart failure, tricuspid regurgitation, pulmonary hypertension, pericardial effusion, or mediastinal masses³. 

Jugular pulsations may be accentuated during abdominal compression and may also occur intermittently with arrhythmias such as complete atrioventricular block¹. 

Palpation and Pulse Analysis 

Palpation of the thorax identifies the point of maximal intensity of the cardiac impulse and detects precordial thrills associated with loud murmurs. Reduced apical impulse intensity may occur with pleural or pericardial effusion, obesity, or decreased myocardial contractility¹. 

Abdominal palpation may reveal hepatomegaly or ascites associated with right-sided heart failure. Femoral pulse evaluation provides information on rate, rhythm, quality, and symmetry. Pulse deficits are characteristic of arrhythmias such as atrial fibrillation¹. 

Auscultation of the Heart 

Auscultation is the most important component of the cardiorespiratory examination. Proper technique requires a quiet environment, systematic valve assessment, and appropriate stethoscope selection¹. 

Heart sounds, murmurs, gallops, and rhythm abnormalities provide direct evidence of structural and functional disease. Murmur timing, point of maximal intensity, and radiation are more diagnostically relevant than loudness alone¹. 

Respiratory Auscultation 

Normal bronchovesicular sounds include both inspiratory and expiratory components. Adventitious sounds provide important diagnostic clues. Crackles are associated with pulmonary edema or fibrosis, wheezes indicate bronchial narrowing, and stridor reflects upper airway obstruction. These findings must always be interpreted in clinical context⁴. 

Conclusion 

A disciplined, systematic cardiorespiratory examination enables early diagnosis, accurate triage, and appropriate management of cardiac and respiratory disease. Despite technological advances, clinical examination remains indispensable in small animal practice (Fonfara, 2015). 

Reference 

1. IONIŢĂ L. THE IMPORTANCE OF CLINICAL EXAMINATION FOR THE DIAGNOSIS OF HEART DISEASE AND LEFT CONGESTIVE HEART FAILURE SYNDROME IN DOGS AND CATS-A REVIEW. Scientific Works. Series C, Veterinary Medicine. 2024 Jul 1;70(2). https://veterinarymedicinejournal.usamv.ro/pdf/2024/issue_2/Art7.pdf 

2. Boswood A, Gordon SG, Häggström J, Vanselow M, Wess G, Stepien RL, Oyama MA, Keene BW, Bonagura J, MacDonald KA, Patteson M, Smith S, Fox PR, Sanderson K, Woolley R, Szatmári V, Menaut P, Church WM, O'Sullivan ML, Jaudon JP, Kresken JG, Rush J, Barrett KA, Rosenthal SL, Saunders AB, Ljungvall I, Deinert M, Bomassi E, Estrada AH, Fernandez Del Palacio MJ, Moise NS, Abbott JA, Fujii Y, Spier A, Luethy MW, Santilli RA, Uechi M, Tidholm A, Schummer C, Watson P.(2020). Temporal changes in clinical and radiographic variables in dogs with preclinical myxomatous mitral valve disease: The EPIC study. J Vet Intern Med. 2020 May;34(3):1108-1118. https://academic.oup.com/jvim/article-pdf/34/3/1108/66660965/jvim15753.pdf 

3. Radulescu, A., Cristescu, B., Harrigan, P., & Ionita, L. (2019). Reversal of cardiac pathology by echocardiography in a dog with severe pulmonary hypertension secondary to heartworm disease-case report. Scientific Works. Series C. Veterinary Medicine, 65(1), 79-88. https://veterinarymedicinejournal.usamv.ro/pdf/2019/issue_1/Art13.pdf 

4. Dupré, G., & Heidenreich, D. (2016). Brachycephalic syndrome. Veterinary Clinics: Small Animal Practice, 46(4), 691-707. https://inglisebuldog.ee/wp-content/uploads/2022/12/article-sindrome-braquicefalic.pdf