Differential diagnosis of equine
murmurs
H. Amory, DVM, PhD, Dip ECEIM
Faculty of veterinary medicine, ULg
From Yann Arthus Bertrand


Cardiac murmur
Introduction

 murmurs:
 Common in horses
 Physiologic or pathologic
 When pathologic: potential cause of exercise
intolerance

Physiologic or pathologic ?
 Clinical examination
 Doppler echocardiography
Murmurs in horse
 Clinical examination
 Differential diagnosis
 Clinical cases
Clinical examination
 General physical examination
 Cardiac auscultation
General physical examination
 General inspection: body condition, peripheral edema,
abdominal distention, respiratory rate & pattern
 Evaluation of the venous circulation:
distention & pulse on the jugular veins
 Mucous membranes: colour, CRT
 Peripheral pulse: rate, rhythm, character, amplitude
Left heart failure
 pulmonary edema,
pleural effusion,…
Right heart failure
 peripheral edema,
venous pulse, ascite,…
Respiratory signs and
cardiac diseases in horses
 Left  diseases = the most frequent  
PAP
 BUT: interstitial (not alveolar) edema 
few respiratory signs
except for: advanced or acute cases
 In most of the cases:
signs of right  failure+++
Clinical examination
 General physical examination
 Cardiac auscultation
Cardiac auscultation:
Characterics of a cardiac murmur
1.
2.
3.
4.
Timing
Intensity
Pitch & quality
Localisation
1. Timing
 Systolic or diastolic ?
Systolic
Diastolic
Systolo-diastolic
(continuous)
1. Timing
 Systolic or diastolic ?
 Identification of S1
1. Timing
 Systolic or diastolic ?
 Identification of S1
Palpation
of the pulse
Systolic
Diastolic
Palpation of the
Precordial choc
1. Timing
 Systolic or diastolic ?
 duration ?
1. Timing
 Systolic or diastolic ?
 duration ?
Mesosystolic
Telesystolic
Holosystolic
2. Intensity
Grade 1: Grade 2: Grade 3: Grade 4: Grade 5: Grade 6: -
Very quiet & localized
 careful & prolonged auscultation at PIM
Quiet & localized
Directly heard on the PMI
Moderately loud
Loud
Over a widespread area
Loud + thrill
Loud + thrill
Heard even when stethoscope just off the
skin surface
2. Intensity
! Intensity of the murmur is not
proportionnal to the severity
of the disease !
3. Pitch & quality
- Pitch & type of murmur
- Evolution of the murmur intensity/time
Decrescendo
Crescendo
4. Localisation
Purpose =
Determine PMI & irradiation
of the murmur
Auscultation:
Mitral valve
 Left
 10 cm > sternum
 Posterior limit of the triceps (IC 4-5)
OR: > olecranon (apex beat area)
 S1 > S2; S3
Mitral valve
M
Auscultation:
Aortic valve





Left
Cranial & dorsal to the mitral valve
Just < point of the shoulder
Under the triceps (IC 4)
S2 > S1
S1 > S2
S2 > S1
Aortic valve
A
M
Auscultation:
Pulmonary valve
Left
Cranial & ventral to the aortic valve
½ distance between point of the schoulder/olecranon
Far forward under the triceps (IC 3)  the leg
must be pushed forwards
 S4




Pulmonary valve
P
A
M
Auscultation:
Tricuspid valve
 Right
 ½ distance between point of the
olecranon/shoulder
 Under the triceps (IC 3 or 4)
Tricuspid valve
A
PT M
Cardiac auscultation:
Characterics of a cardiac murmur
1.
2.
3.
4.
Timing
Intensity
Pitch & quality
Localisation

Differential
diagnosis
Murmurs in horse
 Clinical examination
 Differential diagnosis
Murmur
Physiological
Pathological
Acquired
diseases
Valvular
Insufficiency+++
Congenital
diseases
Valvular
Stenosis
Valvular Insufficiencies





Degenerative disease+++
Ruptured CT
Endocarditis
Myocarditis
Congenital malformation
Cardiac murmur: diagnostic/pronosis
 Doppler echocardiography:
 Morphologic & fonctional cardiac
repercussions
 Localisation & grade of the abnormality
Differential diagnosis of cardiac murmur
 Systolic murmur ?
 Diastolic murmur ?
Systolic murmurs
Diastole
Systolic murmurs
Systole
Systolic murmurs




Ejection (physiologic)
Mitral insufficiency
Tricuspid insufficiency
Ventricular septal defect
Ejection murmur
 Common
 Physiologic
 Proto or mesosystolic
 Grade I to III/VI, localised
 PMI: aortic or pulmonary valve
 Crescendo/decrescendo
  with exercise
Ejection murmur
Differential diagnosis of most common systolic murmurs
Ejection
Mitral Ins.
Tricuspid
Ins.
VSD
Timing
Grade
PMI
Irradiation
Character
Proto
to meso
I-III
Ao & Pu
Localised
Crescendodecrescendo
Systolic murmurs
 Ejection (physiologic)
 Mitral insufficiency
Mitral insufficiency
 Epidemiology:
- Valvular insufficiency the most  associated
with exercise intolerance & CHF
- Middle-aged to aged horses, sometimes
young horses
Mitral insufficiency
 Murmur:
- Holo to holosystolic, sometimes shorter
- Most  band-shaped, sometimes crescendo
or decrescendo
- Soft to rough
- PMI: mitral (aortic) area, irradiating dorsally
& cranially
From Patteson, 1995
Mitral insufficiency
Holosystolic
Holosystolic decrescendo
Mitral insufficiency
Holosystolic crescendo
Telesystolic crescendo
Mitral insufficiency
 Clinical signs:
- Asymptomatic to CHF:
• Poor recovery rates after exercise
• Exercise intolerance, peripheral edema, jugular
pulse, weight loss, etc.
• Arrhytmias (atrial fibrillation)
• Dyspnea & pulmonary edema
Mitral insufficiency
 Clinical signs:
- Asymptomatic to CHF:
• Poor recovery rates after exercise
• Exercise intolerance, peripheral edema, jugular
pulse, weight loss, etc.
• Dyspnea & pulmonary edema
• Arrhythmias (atrial fibrillation when LA )
- If acute (uncommon)  respiratory distress+++
 pulmonary edema or seizures
Mitral insufficiency
 Signs of a favourable prognosis:
 Clinical:
• - Normal resting HR
• - No sign of CHF, exercise intolerance, arrhythmia
• - Murmur grade  III/VI & short in duration
 Doppler Echo :
• - MV: no structural changes, prolapsus 
• - Limited and short regurgitant jet
• - No sign of LV volume overload
• - No dilatation of the LA/Pu
• - No worsening on control echocardiography
Mitral insufficiency
 Signs of a unfavourable prognosis:
 Clinical:
• - Resting HR > 45/min
• - Significant arrhythmias
• - Sign(s) of CHF, exercise intolerance
• - Murmur: grade > III/VI & long in duration
 Doppler Echo :
• - MV: structural changes, flail valve, ruptured CT 
• - Large and persistant regurgitant jet
• - Sign(s) of LV volume overload
• - Dilated LA (except acute cases)/Pu
• - Worsening on control echocardiography
Normal Right LAx 2D 4 cavities view
Normal Right SAx 2D LV view
Normal Right SAx 2D&TM LV view
Normal Left LAx 2D 4 cavities view
Normal mitral flow
Mitral insufficiency
Mitral insufficiency
Mitral insufficiency
From: Patteson, 1995
From: Boon, 1998
From: Marr, 1999
From: Patteson, 1995
From: Boon, 1998
Differential diagnosis of most common systolic murmurs
Ejection
Mitral Ins.
Tricuspid
Ins.
VSD
Timing
Grade
PMI
Irradiation
Character
Proto
to meso
I-III
Ao & Pu
Localised
Crescendodecrescendo

II-VI
Mi (Ao)
Dorsally &
cranially

Systolic murmurs
 Ejection (physiologic)
 Mitral insufficiency
 Tricuspid insufficiency
Tricuspid insufficiency
 Epidemiology:
  in young athletic horses (asymptomatic)
 In other horses: most  = repercussion of a
left  disease
 Murmur:
 Meso to holosystolic
 Soft
 PMI: tricuspid valve, irradiating dorsally &
cranially
From Patteson, 1995
Tricuspid insufficiency
 Clinical signs:
 In young athletic horses (isolated):
• Asymptomatic in most of the cases (physiological ?)
• Rarely: evolution in CHF:
- Poor recovery rates after exercise
- Exercise intolerance, peripheral edema, jugular
pulse, weight loss, etc.
Tricuspid insufficiency
 Clinical signs:
 In other horses: repercussion of a left  disease
 Cfr mitral insufficiency
 Poor prognosis
Tricuspid insufficiency
 Signs of a favourable prognosis:
 Clinical:
• - Normal resting HR
• - No sign of CHF, exercise intolerance, arrhythmia
• - Murmur grade  III/VI & short in duration
 Doppler Echo :
• - TV: no structural changes, prolapsus 
• - Limited and short regurgitant jet
• - No sign of RV volume overload
• - No dilatation of the RA
• - No worsening on control echocardiography
Tricuspid insufficiency
 Signs of a unfavourable prognosis:
 Clinical:
• - Resting HR > 45/min
• - Significant arrhythmias
• - Sign(s) of CHF, exercise intolerance
• - Murmur: grade > III/VI & long in duration
 Doppler Echo :
• - TV: structural changes, flail valve
• - Large and persistant regurgitant jet
• - Sign(s) of RV volume overload
• - Dilated RA
• - Worsening on control echocardiography
Normal tricuspid flow
Tricuspid insufficiency
Tricuspid insufficiency
From Boon, 1998
Tricuspid insufficiency
Tricuspid insufficiency
From Marr, 1999
Tricuspid insufficiency
From Patteson, 1995
Differential diagnosis of most common systolic murmurs
Timing
Grade
PMI
Irradiation
Character
Proto
to meso
I-III
Ao & Pu
Localised
Crescendodecrescendo
Mitral Ins.

II-VI
Mi (Ao)
Dorsally &
cranially

Tricuspid
Ins.

II-VI
Tric
Dorsally &
cranially

Ejection
VSD
Systolic murmurs




Ejection (physiologic)
Mitral insufficiency
Tricuspid insufficiency
Ventricular septal defect
Ventricular septal defect
 Epidemiology:
 Rare; the most  congenital  abnormality
 Can be compatible with a "normal" athletic life
 Murmur:
 Holosystolic,   with a thrill
 Loud: Grade III to VI/VI (intensity not
proportional to severity)
 PMI : right apex (> sternum), irradiating to
the left
From Patteson,
1995
Ventricular septal defect
Ventricular septal defect
 Clinical signs:
  depending on the size of the VSD : from
asymptomatic to CHF
Ventricular septal defect
 Signs of a favourable prognosis:
 Clinical:
• - Normal resting HR
• - No sign of CHF, exercise intolerance, arrhythmia
 Doppler Echo :
- Shunt left  right; Vmax > 4.5 m/sec 
- Not  with other  congenital abnormality
- VSD size < 1/3 of the Aortic 
- No sign of LV volume overload
- No dilatation of the LA/Pu
- No worsening on control echocardiography
Ventricular septal defect
 Signs of a unfavourable prognosis:
 Clinical:
• - Resting HR > 45/min
• - Sign(s) of CHF, exercise intolerance, arrhythmias
 Doppler Echo :
- Shunt right  left; Vmax < 4.5 m/sec 
-  with other  congenital abnormality
- VSD size < 1/3 of the Aortic 
- Sign(s) of LV volume overload
- Dilatation of the LA/Pu
- Worsening on control echocardiography
Ventricular septal defect
Ventricular septal defect
Differential diagnosis of most common systolic murmurs
Timing
Grade
PMI
Irradiation
Character
Proto
to meso
I-III
Ao & Pu
Localised
Crescendodecrescendo
Mitral Ins.

II-VI
Mi (Ao)
Dorsally &
cranially

Tricuspid
Ins.

II-VI
Tric
Dorsally &
cranially

Holo
III-VI
Right apex
Dorsally &
cranially
Bilateral
Band shaped
Ejection
VSD