Myocardial Disease In Dogs Flashcards

1
Q

What are the most common primary myocardial disease in dogs?

A

Dilated cardiomyopathy
Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)

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2
Q

What are some secondary causes of myocardial disease?

A

Infective myocarditis
Deficiency disease
Toxic causes

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3
Q

What is DCM?

A

Dilated cardiomyopathy
Most common cause of myocardial disease in dogs
Characterised by impaired myocardial contractility and dilation of LV

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4
Q

How can you diagnose DCM?

A

Diagnosis by exclusion
Usually end stage of other cardiac diseases

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5
Q

What does DCM look like?

A

Very enlarged heart
Left is more enlarged but often both sides
Looks like a water balloon on PM

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6
Q

What is the pathophysiology of DCM?

A

Eccentric hypertrophy of left ventricle (stretches outwards)
Systolic failure
* Failure of contractility causing forward failure

Backward failure also occurs because blood is not expelled enough and back flows into LA
* Pulmonary oedema

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7
Q

Why does the left atrium dilate in DCM?

A

Loss of systolic function of LV leads to increase of LV pressure
Causes back flow into LA causing that to increase in size

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8
Q

Breed dispositions for DCM

A

DOBERMAN - poor prognosis
Newfoundland
Irish Wolf Hound
St Bernard
Labradors
Great Dane
Cocker spaniels
GSD

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9
Q

Significance of spaniels?

A

Can get endo or myocardial disease!!

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10
Q

Signalment of DCM

A

Deep chested dogs
Middle aged
>12kg

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11
Q

How does DCM occur?

A

Loss of LV systolic function results in low CO (forward failure)
Compensatory mechanisms activated
* Increase in HR, peripheral vasoconstriction

LV fails to empty leading to increased ventricular diastolic pressure

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12
Q

Common presentation of DCM

A

Occult phase - No clinical signs
Symptomatic phase
* LCHF
* Weight loss
* Sudden death
* Atrial fibrillation
* SOFT murmur (valve can’t fully close)
* Dyspnoea

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13
Q

Clinical signs of DCM

A

Tachycardia
* Atrial fibrillation
* Ventricular premature complexes
* Ventricular tachycardia
Variable pulses
Signs of LCHF
* Coughing
Gallop sounds
Soft murmurs

Pale mm
Sluggish CRT

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14
Q

What is sinus arrhythmia? is it normal?

A

The heart rate increases when your dog breathes in, and then slows down while he is breathing out
(Regularly irregular)
THIS IS NORMAL

Absence of sinus arrhythmia is not normal

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15
Q

What would you likely find on echocardiography for DCM?

A

Large round LV with thin LV wall
Poor contractility of LV
Dilated round LA
* Failure of forward flow leads to back up
Degree of mitral regurgitation
Potentially right sided changes

Poor contractility on M-Mode

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16
Q

What would you find on radiography for DCM?

A

Left sided enlargement of cardiac silhouette
Alveolar pattern in caudal lungs due to pulmonary oedema
Air bronchograms
Cranial lobes usually clear

17
Q

What would you find on ECG for DCM?

A

Can be normal

Wide tall complexes

Ventricular arrhythmia
(Ventricles get so enlarged they develop their own electrical impulse which overpowers SAN)
* Ventricular tachycardia

May have atrial fibrillation (No P wave)

18
Q

Treatment for DCM

A

Positive inotrope - Pimobendan (increases contractility)

Loop diuretic - furosemide (decreases water retention)
* Reduces systemic and pulmonary venous hypertension

ACE inhibitor - Inhibits RAAS
(Venous dilation to reduce venous hypertension)

19
Q

What is Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC)?

A

Rhythm disturbance caused by cardiac muscle in RIGHT ventricle

Myofibre atrophy, fibrosis and fatty infiltration

Left ventricle involved later in disease

20
Q

ARVC breed disposition

A

BOXERS

21
Q

What are the stages of ARVC?

A
  • Asymptomatic with ventricular arrhythmia
  • Symptomatic (syncopal/weak) but with normal heart size and LV function
  • CHF - poor myocardial function
22
Q

Cinical signs of ARVC

A

Syncope and sudden death
Arrhythmia
* Sinus tachycardia
* Atrial fibrilation
Tachypnoea
Pleural effusion/pulmonary oedema

23
Q

Diagnostic method for ARVC

A

24 hour holter monitor ECG for screening

24
Q

Treatment for ARVC

A

First treat heart failure as normal (furosemide, pimobendan, ACE inhibitor, spironolactone)
Anti-arrhythmic medication (Beta-blockers)
* Solatol

Thoracocentesis/abdominocentesis

25
Q

Causes of secondary myocardial disease

A

Myocarditis - infectious or non-infectious
Doxorubin (chemotherapy drug)
Metabolic/nutritional deficiencies
* L-carnitine and Taurine
Ischaemic heart disease (clots)
Tachycardia-induced cardiomyopathy (electrical dysfunction)
* Supraventricular tachycardia

26
Q

What is hypertrophic cardiomyopathy?

A

Concentric hypertrophy of ventricular cardiac muscle
RARE in dog
Diastolic failure - failure to fill ventricles

27
Q

consequence of LCHF

A

Pulmonary oedema

28
Q

Consequence of RCHF

A

Pleural effusion