Cardio disease

• The start of a physical examination should be done from a distance to assess respiratory effort. This can be done by looking at stance (elbows abducted = pleural disease/chest pain) and listening for coughing. It can also be helpful to identify if there is more effort on inspiration or expiration.
• Only the submandibular lymph nodes are palpable (small hard edamame beans). Many other lymph nodes of the head that are difficult to differentiate from salivary glands
• • Is there air moving throughout the entire lung field?
  • Areas of dullness suggest pleural effusion or pulmonary consolidation/abscessation/masses
  • Are there any abnormal sounds?
  • Large airway sounds suggest consolidation
  • Wheezes and crackles suggest airway narrowing, or discharges in airways
  • Does the horse tolerate and recover from re-breathing rapidly?
  • Coughing and distress suggest pleural pain
  • Is there a tracheal rattle?
  • This suggests that there is discharge pooling at the thoracic inlet
  • Horses can get pulmonary oedema it just isn't common
• A rebreathing bag can aid with auscultation and involves a large garbage bag being placed over the nares (easier to just place over the whole muzzle). This causes the horse to rebreathe air causing a build-up CO2. This drives the respiratory centres causing more deeper, more rapid breaths.

  • Rebreathe until animal starts to become distressed but not until complete panic occurs (be sympathetic)

  Continue to listen throughout the rebreathing process.
• It is also possible to perform an arterial blood gas analysis (done in significant cardiorespiratory disease or in some cases of poor performance) to test respiratory function but this is reserved for specialist procedures.

  • Hypoxia = PaO2 less than 80mmHg
  • Hypercapnia= PaCO2 more than 45mmHg
• Cardiac disease is often identified incidentally but can still be important. Pericardial disease is much rarer

  A) hypovolaemia

  B) lameness

  C) pulmonary oedema

  D) furosemide

  E) endocarditis

  F) peripheral

  G) endocardial

  H) common

  
• The examination of the cardiovascular system is not just cardiac auscultation, also assess…

  • Pulses : Arterial and venous
  • Also assess the peripheral vessels
  • Periphery : Oedema
  • This is often ventral but it is very common to occur in front of the front legs
  • This can occur due to…
  • Right sided heart failure
  • Hypoproteinaemia
  • Vascular disease
  • Mucous membranes
• • Jugular pulsation is normally visible in distal third of neck and is dependent on head and neck position, if you can see this beyond this then consider cardiac disease. Jugular distension is an indicator of reduced cardiac return which can indicate…
  • Right sided Cardiac failure
  • Thoracic disease
  • Pericardial disease
• ips for auscultation are…

  • To start on the left
  • Listen just behind triceps…
  • Halfway between elbow and shoulder. The left IC 5 is where you can listen to the mitral valve
  • Under triceps at the left IC 4  allows for auscultation of the aortic (and pulmonic valve)
  • Then move onto the right
  • Listen under the triceps. Moving the leg forward can help with this
• Normal heart sounds include…

  • S4 (shh sound)
  • This indicates the onset of atrial systole and is not always heard
  • S1 (Lub sound)
  • This indicates the onset of ventricular systole and the closure of AV valves and opening of Semilunar valves
  • This sound is loudest over left IC 5
  • S2 (Dub sound)
  • This indicates the onset of diastole and the closure of semilunar valves, open AV
  • This is loudest over left IC 4
  • S3 (de sound)
  • This indicates rapid ventricular filling and is loudest over the cardiac apex (low LIC5)
• Normal heart sounds are caused by turbulence which can be due to the closure of cardiac valves or high velocity flow. Murmurs are due to forward or reverse flow.
• Cardiac murmurs are a common finding in all types of horses and can be due to…

  • Physiological (ejection type) murmurs
  • Endocardial (valvular disease)
  • Valvular regurgitation causes the sound and can occur due to endocarditis or endocardosis
  • Congenital cardiac defects e.g., VSD
• Murmurs can then be classified based on…

  • Grade / Intensity
  • This is a poor indicator of severity however quite murmurs are less likely to be important
  • Timing
  • Systole vs Diastole
  • Radiation
  • Dorsal or Ventral
  • Point of maximal intensity
  • Cranial -intercostal space 4
  • Caudal -intercostal space 5
• • In horses timing usually determined by relative duration of diastole / systole. A diastolic murmur is more common than in small animals
  • Concurrent palpation of arterial pulse is difficult especially if using facial artery. Hence, consider using brachial artery (inside elbow)
  • Substitute jugular venous pulse
• fill in the blanks

  A) holo

  B) pan

  C) mid

  
• Other assessments of cardiac function include…

  • Blood pressure (rarely done)
  • Direct or indirect methods
  • Cardiac output
  • Dilution techniques (dye, temperature)
  • Ultrasound
  • VO2 Max.
  • Maximum tissue uptake
  • Requires high speed treadmill, expired gas analysis
• To assess cardiac murmurs perform…

  • Cardiac auscultation
  • Timing and PMI
  • History and physical examination to determine which horses require further investigation
  • Echocardiography to confirm diagnosis, prognosis and safety
  • Electrocardiography
  • Concurrent dysrhythmias provides a definitive diagnosis but also gives information on prognosis and rider safety
• Endocardosis causes progressive valvular degeneration and can affect the mitral, aortic, tricuspid valves
• Endocarditis is bacterial in origin secondary to bacteraemia causes include…

  • Cattle: Liver abscess, TRP, mastitis
  • Equine: Dental, respiratory, thrombophlebitis

  Other causes include…

  • Valve dysplasia
  • Valvulitis
  • Valve prolapse
  • Ruptured chordae tendinae
• Clinical signs of bacterial endocarditis include…

  • The acute onset congestive heart failure
  • Fever
  • Cardiac murmur
  • Tachycardia
  • Tachypnoea

  Laboratory data often shows hyperfibrinogenaemia, anaemia and leucocytosis. To isolate the causative bacterium perform a blood culture
• Treatment of bacterial endocarditis involves broad spectrum antibiotics based on sensitivity. However, the prognosis is guarded even after a bacteriological cure due to the permanent structural damage to the valve.

  • Right-sided lesions may have the return of performance

  Septic emboli may shed to distant sites such as the lungs (right heart) or the kidneys / joints etc (left heart).
• fill in the blanks

  A) physiological

  B) ejection

  C) filling

  D) mitral

  E) tricuspid

  F) aortic

  
• A systolic murmur is heard throughout systole (S1 to S2), a diastolic murmur is heard throughout diastole (S2 to S1) while a continuous murmur is heard through both systole and diastole.
• With a holosystolic and holodiastolic murmur you can still hear S1 and S2.
• you cannot hear S1 and S2 with pansystolic or pandiastolic murmurs.
• pandiastolic can be hard to differentiate from pansystolic but remember the diastolic phase is longer.
• a Band/Plateau murmur maintains intensity
• Crescendo murmurs increases in intensity
• decrescendo murmurs decrease in intensity
• mitral regurgitation murmurs can present in all age groups and are often incidental findings but they can cause collapse and sudden death
• what is the PMI of a mitral regurgitation murmur?

  left
• you identify a Systolic pathological murmur with a PMI on the LHS, what is the likely cause?

  mitral regurgitation
• you identify a systolic pathological murmur with a PMI on the RHS, what is the likely cause?

  tricuspid regurgitation
• tricuspid regurgitation affects all age groups, specifically in racing TB and SB horses. these are often incidental findings but can lead to collapse and sudden death
• Pulmonic insufficiency is uncommon in horses. Regurgitation is commonly seen on doppler echocardiography but this rarely affects performance
• you hear a diastolic pathological murmur with a PMI on the LHS what is the likely cause?

  aortic regurgitation
• aortic regurgitation is often identified in middle to older horses. it can be an incidental finding but can also be progressive and lead to clinical signs once the horse is older
• When you hear a cardiac murmur…

  • Perform a cardiovascular assessment
  • Characterise the murmur
  • Further investigation?
  • Echocardiography
  • +/-resting ECG
  • +/-exercising ECG
• fill in the blanks

  A) tricuspid

  B) aortic

  C) progressive

  D) acute

  E) myocardial

  F) arrhythmias

  
• a horse presents with an acute onset of exercise intolerance and pain with a continuous murmur, what is the top differential?

  aorto - cardiac fistula