Clinical Value of Medical History in Cardiac and Respiratory Disorders of Dogs and Cats

Despite the rapid evolution of cardiac diagnostic tools such as echocardiography, advanced imaging, and biomarker testing, the value of medical history and clinical examination in veterinary cardiology remains unquestionable. These initial steps often provide the first diagnostic clues and are particularly critical in emergency situations involving cardiac, respiratory, or vascular disease. A carefully obtained history can guide immediate therapeutic decisions, help differentiate cardiac from respiratory pathology, prioritize diagnostic testing, and provide an objective baseline for evaluating therapeutic response¹. 

Signalment as the Foundation of Diagnosis 

The first component of medical history is signalment, including age, sex, and breed. This information alone can significantly narrow differential diagnoses, as many cardiovascular diseases have breed and age predilections². For example, large-breed dogs are more predisposed to dilated cardiomyopathy, while small-breed dogs commonly develop degenerative mitral valve disease. Signalment should always be interpreted alongside clinical signs to establish diagnostic direction. 

Structured Anamnesis: Asking the Right Questions 

A structured anamnesis is essential and should include the reason for consultation, onset of signs, duration, progression, vaccination and heartworm prophylaxis status, current medications, response to therapy, and the owner’s ability to administer medications reliably. Each of these elements has direct diagnostic and therapeutic implications¹. 

Additional targeted questions help define major problems. For respiratory difficulty, the clinician should clarify whether signs occur at rest or during exertion, whether onset was sudden or gradual, and whether audible respiratory noise is present, which may suggest upper airway obstruction¹. 

Historical Signs Suggestive of Cardiorespiratory Disease 

Several clinical signs overlap between cardiac and respiratory disease. These include tachypnea, dyspnea, coughing, exercise intolerance, difficulty sleeping, and general malaise. These abnormalities are frequently underestimated by owners, especially when they develop slowly over time. Abnormal respiratory patterns are particularly likely to be overlooked and often only become evident during clinical examination¹. 

Other historical findings with diagnostic relevance include anorexia, weight loss or cachexia, abdominal distention from hepatomegaly or ascites, diarrhea associated with severe right-sided heart failure, hemoglobinuria in caval syndrome of dirofilariasis, hemoptysis associated with pulmonary thromboembolism or pneumonia, exertional collapse, syncope, seizures, and acute hind limb paresis or paralysis¹. 

Syncope: Cardiac or Respiratory Origin? 

Syncope represents a key diagnostic challenge. It may originate from cardiac, vascular, or respiratory disease. Respiratory syncope is often associated with pulmonary arterial hypertension, severe bronchopulmonary disease, pleural space disease, or obstructive upper airway conditions, particularly in brachycephalic breeds¹. 

Cardiogenic syncope may result from reduced cardiac output, reflex-mediated vasovagal events, or arrhythmias such as sinus arrest, atrioventricular block, or ventricular tachycardia. Structural abnormalities such as subaortic stenosis, pulmonary stenosis, or tetralogy of Fallot may also contribute¹. 

Cardiac syncope is typically sudden, brief (less than one minute), exercise-related, and followed by rapid recovery. Unlike seizures, tonic-clonic movements, hypersalivation, and postictal behavior are absent. These distinctions are critical in differentiating syncope from neurologic disease¹. 

Exercise Intolerance and Owner Perception 

Exercise intolerance is a sensitive but nonspecific indicator of heart disease. Many owners fail to recognize this sign, particularly in sedentary dogs or breeds with naturally low activity levels, such as English Bulldogs³. Cats, due to their intermittent activity patterns, may not show obvious exercise limitations until disease becomes advanced. 

Exercise intolerance can also be caused by respiratory, musculoskeletal, neurologic, metabolic, endocrine, or hematologic disease, including anemia, thyroid disorders, adrenal disease, diabetes mellitus, or electrolyte imbalances. 

Coughing: A Frequent but Misleading Sign 

Coughing is one of the most commonly reported signs in dogs with suspected heart disease, yet it is often non-cardiac in origin. While pulmonary edema and left atrial enlargement can contribute to coughing, many dogs with chronic valvular disease have concurrent airway pathology such as chronic bronchitis, tracheal disease, bronchomalacia, or pulmonary fibrosis¹. 

Upper airway disease typically causes a loud, paroxysmal cough worsened by exertion, whereas so-called “cardiac cough” is usually low-intensity, intermittent, and associated with dyspnea or nocturnal agitation. 

Clinical Relevance 

A complete and accurately interpreted medical history often allows early differentiation between cardiac and respiratory disease, enabling targeted diagnostics and avoiding unnecessary or stressful procedures in compromised patients. 

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. Keene BW, Atkins CE, Bonagura JD, Fox PR, Häggström J, Fuentes VL, Oyama MA, Rush JE, Stepien R, Uechi M. ACVIM consensus guidelines for the diagnosis and treatment of myxomatous mitral valve disease in dogs. Journal of veterinary internal medicine. 2019 May;33(3):1127-40. https://academic.oup.com/jvim/article-pdf/33/3/1127/66659642/jvim15488.pdf 
3. Chong, L. Y., & YiJun, L. (2017). Cat owners’perception towards feline heart disease: a behavioural study. Veterinary sciences, 90. http://psasir.upm.edu.my/id/eprint/83369/1/FPV%202017%204%20-%20IR.pdf