Contributors: Yolanda Martinez Pereira, Mark Oyama

 Species: Canine   |   Classification: Miscellaneous


History taking

Background history

  • Enquiring about the origin of the pet (eg registered breeder, private breeder, puppy farm) should help identify congenital problems (eg murmur noted at puppyhood) and familial problems (sudden death within littermates, etc).
  • Travel history is recommended, as well as history of previous tick exposure - myocarditis Heart: myocarditis has been reported with tick-borne diseases and other diseases foreign to the UK.
  • History of previous diseases and/or traumas should be collected.
  • Collection of information regarding current medication, as well as clinical response to previous treatments (eg chronic coughing over years that improves with steroid or bronchodilator treatment is more likely to be due to underlying respiratory disease than cardiac disease).
  • History of vaccination status and previous worming - special consideration should be taken to ensure that the worming drug used offers preventative treatment for diseases such as lungworm Oslerus osleri infection or heartworm Canine cardiopulmonary dirofilariasis , that can lead to coughing.
  • It is important to obtain information regarding the level of activity of the patient, as it will help interpreting the severity of clinical signs such as decreased exercise tolerance, eg decreased exercise tolerance is likely to be less noticeable in patients that only go out for short walks on the lead versus patients that have a more active routine of exercise.
  • History of presence of murmur in the past, and its intensity.

History for specific complaints


  • Syncope is defined as transient loss of consciousness caused by insufficient cerebral blood perfusion. It is usually of very short duration and it is not preceded by a pre-ictal or followed by a post-ictal phase (eg patient is back to his normal self within minutes after the episode). If the lack of cerebral blood flow is prolonged, a tonic-clonic episode may follow.
  • Pre-syncopal episodes are characterized by transient weakness, without full loss of consciousness.
  • Collapse Collapse is a general term used commonly by owners and can refer to syncope, weakness, neurological disorders, etc.
  • Neurological episodes (such as tonic-clonic seizures and petit mal type of seizures Seizures ) may be mistaken for cardiac syncope by owners - history should help differentiating between them:
    • Presence of pre-ictal and post-ictal phase (eg long versus short recovery after the episode).
    • Presence of tonic-clonic contractions and/or muscular spasticity (more common with neurological disease).
    • Duration of episode: very transient episodes (less than 1 minute) are often due to cardiac syncope.
  • Other differential diagnoses for syncopal episodes include metabolic problems (eg anemia Anemia: overview ), endocrine problems (hypothyroidism Hypothyroidism , hypoadrenocorticism Hypoadrenocorticism ), orthopedic problems, internal bleeding (eg abdominal hemangiosarcoma Hemangiosarcoma ), respiratory disease (eg laryngeal paralysis Larynx: paralysis ), etc - a full clinical history should be taken in patient presenting with collapse/syncope/weakness to help shortening the differential diagnosis list as much as possible.
  • When several episodes are reported the following questions should be asked:
    • Total number of episodes, with dates.
    • Do all episodes look the same?
    • Which activity was the patient doing at the time of the collapse? (Seizures more commonly occur during sleep whereas cardiac problems are more common during exercise.)
    • Any triggers, eg tussive syncope?
    • What is the duration of the episode?
    • Is the patient unconscious?
    • Any urination/defecation/vomiting?
    • Are the muscles floppy or spastic? Any tonic-clonic movements?
    • How is the breathing? Any abnormal respiratory sounds?
    • Was any change in the color of the mucous membranes noted (pale, cyanotic)?
    • If the chest was palpated - was the apex beat very slow or very fast?
    • How was the recovery? How long does it take to be back to normal? How is the patient behaving after the episode?


  • Coughing is one of the most common complaints in patients with cardiac disease, but also in patients with respiratory disease.
  • In cardiac patients, coughing is usually triggered by underlying primary airway disease and perhaps physical compression of the enlarged heart on the airways. Patients with pericardial effusion Pericardial disease can also present with coughing.
  • Additional history to be taken in patients with coughing:
    • Is it productive, non-productive?
    • What's the frequency, eg daily, nocturnal, etc?
    • What's the progression (acute coughing versus chronic coughing)?
    • Any triggers?

Physical examination

General examination

  • Patient demeanor and responsiveness, eg bright, alert and responsive.
  • Body condition score - a scale out of 9 can be used.
  • Assessment of the resting respiratory rate and the breathing pattern.

Cardiovascular examination

  • Mucous membranes (conjunctival, buccal, vaginal/preputial) - the color and the capillary refill time should be assessed. It should be noted if they are wet, tacky or dry and if ecchymoses or petechiae are noted:
    • Pale mucous membranes may be present in anemic patients, with hemorrhage and in patients with peripheral vasoconstriction (shock, poor cardiac output, dehydration, etc).
    • Cyanotic mucous membranes can be present in patients with respiratory condition, left congestive heart failure, and right-to-left (reversed) cardiac shunts (eg reversed patent ductus ateriosus Patent ductus arteriosus , reversed ventricular septal defect Ventricular septal defect , reversed atrial septal defect Atrial septal defect ) and complex cardiac congenital disease Congenital heart disease: overview (Tetralogy of Fallot Tetralogy of fallot ).
    •  Differential cyanosis (pink mucous membranes cranially but cyanotic membranes caudally) can be found in reversed patent ductus arteriosus, especially after exercise.
    • Congested mucous membranes can be noted in polycythemic patients - this could be secondary to left-to-right cardiac shunts, chronic respiratory disease or neoplasia.
  • Chest palpation and percussion:
    • Chest palpation: the apex beat should be palpated, as it can be displaced caudally in patients with cardiomegaly, or can be laterally displaced with presence of intra-thoracic masses. It also allows assessment of the heart rate and rhythm, and the relationship between heart beats and femoral pulses. It may not be easy to feel in obese patients and in patients with effusions, pneumonia, intra-thoracic masses or pneumothorax Pneumothorax. In patients with severe murmurs (grade V and VI/VI), a thrill can be palpated over the point of maximum intensity.
    • Chest percussion can be useful in detecting pleural effusion in medium and large canine patients Coupage. The resonance will be increased dorsally in patients with pneumothorax.
  • Pulse assessment: the rate and quality of the pulse should be assessed, as well as the presence of pulse deficits (eg one heart beat not followed by a palpable pulse). Some examples of abnormal pulses are:
    • Weak pulses: found in patients with poor cardiac output, such as patients with Dilated Cardiomyopathy Heart: dilated cardiomyopathy (DCM) or in case of hypovolemic or hemorrhagic shock Shock: cardiogenic , congestive heart failure, etc.
    • Hyperdynamic pulses: found in patients with a bigger difference between systolic and diastolic pulses, such as patients with congenital Patent Ductus Arteriosus and patients with significant aortic insufficiency.
    •  Pulsus alternans can be found in patients with myocardial failure and with arrhythmias (rare).
    •  Pulsus paradoxus can be found in patients with pericardial effusion and cardiac tamponade - pulses become very weak or are not palpable during inspiration and become stronger during expiration.
    •  Pulsus parvus et tardus represents a weak and delayed pulse in relation to the heart beat, described in patients with severe aortic stenosis.
    • Lack of pulses can be found secondary to arrhythmias (premature beats often lack a palpable peripheral pulse) or if a thrombus is present, such as in feline patients with aortic thromboembolism.
  • Jugular vein inspection should be carried out in all patients but is especially important in patients with clinical signs suggestive of right congestive heart failure (eg abdominal effusion) or pericardial effusion, in which jugular veins are usually distended or pulsating. In patients with non-cardiac abdominal effusion, the jugular veins should be normal:
    •  Hepatojugular reflux: in patients with abdominal effusion due to right congestive heart failure, applying gentle pressure over the liver can cause temporary jugular distension.

Thoracic auscultation

  • Assessment of the audibility of the heart beat - muffled heart sounds can be found in patients with pericardial or pleural effusions, obesity, pneumothorax, pneumonia, intrathoracic masses Thorax: masses.
  • The heart rate and rhythm should be assessed and recorded:
    • Regular rhythm.
    • Regularly irregular rhythm - if variations are rhythmic with breathing phase (faster during inspiration, slower during expiration) with a normal rate, sinus arrhythmia is likely.
    • Irregulary irregular rhythm (as in atrial fibrillation Heart: atrial fibrillation ).
    • Tachycardia/bradycardia.
  • The presence of murmurs should be assessed and recorded.
  • Intensity of the murmur - over a scale out of VI Murmur: overview :
    • Grade I - only heard in very quiet environment in a calm patient, difficult to hear.
    • Grade II - very quiet murmur but can be heard clearly when in the right position.
    • Grade III - easy to hear but not louder than the first and second heart sounds (S1, S2).
    • Grade IV - easy to hear, louder than the cardiac sounds.
    • Grade V - loud murmur, a thrill can be palpated.
    • Grade VI - loud murmur, a thrill can be palpated and the murmur can be heard when the stethoscope is separated from the chest wall.
  • Timing:
    • Systolic - the most common murmur in small animals, caused by mitral/tricuspid valvular regurgitation Atrioventricular valve dysplasia and aortic/pulmonic stenosis Pulmonic stenosis.
    • Diastolic - less common murmur, found associated with aortic and pulmonic insufficiency or mitral/tricuspid stenosis.
    • Continuous - found in conditions such as congenital patent ductus arteriosus.
    • To-and-fro (crescendo systolic and decrescendo diastolic murmur) - less common, usually caused by complex congenital heart disease, eg ventricular septal defect with concurrent severe aortic insufficiency Ventricular septal defect.
  • Character:
    • Harsh or ejection murmur.
    • Soft or regurgitant murmur.
  • Point of maximum intensity:
    • Left base.
    • Left apex.
    • Right.
  • Presence of other abnormal heart sounds should be assessed such as
    o Split S2 - found in patients with pulmonary hypertension Pulmonary Arterial Hypertension (PHT).
    o Gallop sound - relatively common in feline patients with cardiomyopathy and less frequently in dogs with cardiac disease.
  • Lung auscultation should include the four quadrants of the lungs and auscultation of the upper airway (to detect referred upper respiratory noise). Abnormal lung sounds are more commonly found in patients with coughing due to respiratory disease such as:
  • Abdominal palpation: in patients with right congestive heart failure we should assess:
    • Organomegaly - hepatomegaly and splenomegaly can be palpated due to congestion.
    • Positive ascitic wave.
  • Other parts of the physical examination are important in patients presenting with decreased exercise tolerance, syncope, etc, as for example:

Diagnostic tests