Canine cardiomyopathy

Question 1

What is canine cardiomyopathy?

Answer 1

Intrinsic abnormality of the myocardium independent of any congenital or acquired cardiac diseases that lead to volume or pressure overload

Canine cardiomyopathy encompasses several specific conditions affecting the heart muscle.

Question 2

List 6 examples of canine cardiomyopathy.

Answer 2

1. DCM
2. ARVC
3. Atrioventricular myopathy
4. Golden Retriever muscular dystrophy
5. Myocarditis
6. HCM

DCM refers to dilated cardiomyopathy, ARVC to arrhythmogenic right ventricular cardiomyopathy, and HCM to hypertrophic cardiomyopathy.

Question 3

What is the significance of Golden Retriever muscular dystrophy in relation to cardiomyopathy?

Answer 3

It is analogous to Duchenne muscular dystrophy in people

This condition affects the muscles and can have cardiac implications.

Question 4

What is DCM characterized by?

Answer 4

1. Cardiac dilation
2. systolic dysfunction
3. • often diastolic dysfunction

Question 5

In dogs with DCM and concurrent atrial fibrillation, which type of heart failure is more commonly manifested?

Answer 5

R-CHF in addition to L-CHF

Question 6

Which breeds are most commonly affected by DCM?

Answer 6

Large or giant breed dogs

Question 7

What are the the two classifications of DCM?

Answer 7

1. Primary (idiopathic)
2. secondary causes

Question 8

Name 6 secondary causes of DCM

Answer 8

1. Nutritionally mediated
2. Myocarditis (infectious/non-infectious)
3. Metabolic
4. Tachycardia-induced
5. Drugs
6. Toxins

Question 9

List 2 metabolic causes of DCM

Answer 9

• Thyroid deficiency
• Hypoadrenocorticism

Question 10

What drug can cause DCM?

Answer 10

• Doxorubicin

Question 11

What are the two phases of DCM?

Answer 11

• Occult
• Clinical

Question 12

What characterizes the occult phase of DCM?

Answer 12

Significant structural changes and/or arrhythmias without clinical signs

Question 13

What clinical signs may be present in the clinical phase of DCM?

Answer 13

• VTs
• SVTs
• Atrial fibrillation
• L-CHF, R-CHF or bilateral
• Lethargy
• Inappetence
• Increased RR + effort
• Cough
• Weakness
• Exercise intolerance
• Presyncope or syncope
• Weight loss
• Abdominal distension

Question 14

Name 5 physical examination findings in DCM?

Answer 14

• Obtundation
• Tachycardia
• Tachypnea
• Increased respiratory effort or cough
• Hypokinetic or absent pulses

Question 15

What are signs of R-CHF in DCM?

Answer 15

• Jugular venous pulsation or distension
• Abdominal distension
• Abdominal fluid wave

Question 16

What auscultation findings may indicate DCM?

Answer 16

• S3 gallop sound from systolic dysfunction
• Left apical systolic murmur (mitral regurgitation)
• Arrhythmia

Question 17

What are the diagnostic tools used for DCM?

Answer 17

• Echocardiography
• Thoracic radiographs
• Caridac Biomarkers

Question 18

What echocardiographic chagnes can be present in DCM?

Answer 18

• LV dilation in systole, diastole, or both
• LV systolic dysfunction +/- diastolic dysfunction

Question 19

What are radiographc signs of L-CHF in DCM?

Answer 19

1. LV + LA dilation
2. Interstitial/alveolar pattern (most common caudodorsal lung lobes)
3. pulmonary venous distention

Question 20

What is the sensitivity and specificity of cTnI > 0.22ng/ml for occult DCM in Dobermans?

Answer 20

Sensitivity: 80%
Specificity: 84%

Question 21

What cTnI level may predict the risk of sudden cardiac death in Dobermans with enlarged hearts?

Answer 21

> 0.34 ng/ml

Question 22

What is the the sensitivity and specificity of NT-proBNP > 0.550 pmol/L for DCM?

Answer 22

Sensitivity: 79%
Specificity: 90%

Question 23

What factors influence the prognosis of DCM?

Answer 23

• Underlying cause
• Timing of intervention

Question 24

What is recommended for annual screening in dogs used for breeding purposes within suspect breeds?

Answer 24

Echocardiography and 24hr Holter ECG

Question 25

How can LV systolic function be assessed in echocardiography?

Answer 25

1. %FS 2. %EF 3. Fractional area changes (%FAC) 4. Sphericitiy index 5. E-point-to-septal-separation in conjunction with %FS

Question 26

How can mitral or tricuspid regurgitation be assessed in echocardiography?

Answer 26

1. color + spectral doppler echocardiography 2. diastolic dysfunction

Question 27

How is the LV size echocardiographically assessed?

Answer 27

1. M-mode or two-dimensional imaging; measuring diameter of LV at end-diastole and end-systole 2. Left ventricular area and volume measurements indexed to BW

Question 28

What does a cardiac TnI > 0.22ng/ml suggest in a Doberman?

Answer 28

Occult DCM

Question 29

What other (pathological) factors can cause an increase in NT-proBNP levels?

Answer 29

1. renal dysfunction 2. pulmonary hypertension 3. Sepsis 4. Systemic hypertension 5. inappropriate sampling handling

Question 30

What is the prevalence of DCM in Doberman in North America?

Answer 30

45-63% ## Footnote DCM stands for Dilated Cardiomyopathy.

Question 31

What is the most common cause of DCM in Doberman?

Answer 31

Hereditary ## Footnote DCM is often inherited in Doberman dogs.

Question 32

At what age does DCM typically onset in Doberman?

Answer 32

Approx. 6 years ## Footnote This is the average age for the onset of symptoms.

Question 33

What are the two causative genetic mutations associated with DCM in Doberman?

Answer 33

* Gene encoding the mitochondrial protein pyruvate dehydrogenase kinase 4 * Titin gene ## Footnote Both mutations are autosomal dominant with incomplete penetrance and variable expression.

Question 34

What is the effect of being homozygous for the genetic mutations related to DCM?

Answer 34

More severe form ## Footnote Homozygous individuals may experience a more severe manifestation of the disease.

Question 35

Name 7 clinical sequelae of DCM in Doberman?

Answer 35

1. Syncope 2. Sudden death from ventricular arrhythmias 3. L-CHF 4. R-CHF 5. Bilateral CHF 6. Supraventricular tachycardias 7. Atrial fibrillation ## Footnote These outcomes highlight the serious nature of the disease.

Question 36

What is the treatment option during the occult phase of DCM?

Answer 36

* Pimobendan * ACE inhibitors * Beta blockers ## Footnote Each treatment has different effects on delaying the onset of CHF and sudden death.

Question 37

What is the benefit of pimobendan in the occult phase?

Answer 37

Delays onset of CHF and suddenc death up to 9 months ## Footnote Pimobendan is effective in treating the occult phase of DCM.

Question 38

What is the benefit of ACE-inhibitors in the occult phase?

Answer 38

Delays onset of CHF and suddenc death up to 3 months ## Footnote ACE inhibitors are another treatment option during the occult phase.

Question 39

What is the effectiveness of beta blockers in delaying progression of DCM?

Answer 39

Not proven effective ## Footnote Carvedilol is an example of a beta blocker used, but its efficacy is uncertain.

Question 40

When should treatement for ventricular arrhythmias that match criteria of malignancy be instigated?

Answer 40

Treat promptly ## Footnote Timely intervention is crucial for managing serious arrhythmias.

Question 41

What is the long-term treatment for ventricular arrhythmias in Dobermans with DCM?

Answer 41

* Sotalol (1-3mg/kg PO q12hr) = potassium channel blocker * Mexiletine (5-8mg/kg PO q8hr) = sodium channel blocker --> Both together work synergistically ## Footnote Sotalol is a potassium channel blocker, while Mexiletine is a sodium channel blocker.

Question 42

What is an adjunctive treatment for DCM in Dobermans and what is its MOA

Answer 42

Fish oils (1200mg/8kg) --> combats cardiac cachexia ## Footnote Fish oils can help combat cardiac cachexia from CHF.

Question 43

What is the prevalence of Great Danes affected by DCM and what is the age of onset?

Answer 43

3.9-11.8% - adult onset ## Footnote This prevalence indicates the proportion of Great Danes that may experience cardiac-related problems.

Question 44

What are common arrhythmias seen in Great Danes with DCM?

Answer 44

* Atrial fibrillation * Ventricular arrhythmias ## Footnote These arrhythmias may occur alone or alongside other cardiac structural changes and congestive heart failure (CHF).

Question 45

What is the inheritance pattern of familial DCM in Irish Wolfhounds and what is the age of onset?

Answer 45

Autosomal recessive or autosomal dominant (NA) Age of onset: adult ## Footnote The exact inheritance pattern is not clearly defined, indicating variability in genetic transmission.

Question 46

What condition can Irish Wolfhounds develop prior to cardiac structural changes?

Answer 46

Atrial fibrillation ## Footnote This can occur before the onset of congestive heart failure (CHF).

Question 47

What is the age of onset for Standard Schnauzers to develop CHF?

Answer 47

1.5 years in males and 2.35 years in females ## Footnote Standard Schnauzers are prone to early onset of congestive heart failure.

Question 48

What genetic mutation is associated with Standard Schnauzers?

Answer 48

Mutation in the RNA binding motif protein 20 gene ## Footnote This mutation is linked to their autosomal recessive inheritance pattern.

Question 49

What is the typical age of onset of DCM for the Portuguese Water Dog and what is its geneic inheritance?

Answer 49

Juvenile onset (2-32w) - autosomal recessive ## Footnote This breed shows symptoms early in life, typically leading to rapid disease progression.

Question 50

What is the prognosis for Toy Manchester Terriers with familial heart issues?

Answer 50

Die <1 year of age of sudden death without overt signs of heart disease familial inheritance ## Footnote This indicates a high risk of early mortality associated with the condition.

Question 51

What type of degenerative disease is associated with a cardiac disease Golden Retrievers?

Answer 51

Golden Retriever muscular dystrophy --> development of DCM in addition to musculoskeletal abnormalities ## Footnote This condition is analogous to human cardiomyopathy seen with Duchenne muscular dystrophy.

Question 52

What is the inheritance pattern for Golden Retriever muscular dystrophy?

Answer 52

X-linked pattern of inheritance ## Footnote This means the condition is passed on through the X chromosome, affecting males more severely.

Question 53

What is the role of dystrophin for cardiac function?

Answer 53

maintains normal cardiac and skeletal muscle structure ## Footnote Mutations in dystrophin contribute to the risk of developing dilated cardiomyopathy (DCM) in these dogs.

Question 54

What are the potential cardiac changes in Great Danes?

Answer 54

* Arrhythmias * Cardiac structural changes * CHF (predominantly L-CCHF) ## Footnote These changes can occur individually or in combination.

Question 55

Is it clear if cardiac chamber enlargement in Irish Wolfhounds is primary or secondary?

Answer 55

Unclear if primary change or secondary to sustained atrial fibrillation ## Footnote This ambiguity suggests further research is needed to understand the disease mechanism.

Question 56

What is a key difference in disease manifestation of Irish Wolfhounds in Europe vs. NA?

Answer 56

Disease may manifest differently in Europe vs. NA ## Footnote Geographic differences may influence the presentation and severity of symptoms.

Question 57

What is the age of onset for the Portuguese Water Dog's condition?

Answer 57

Juvenile onset ## Footnote Symptoms develop rapidly, often leading to early mortality.

Question 58

What inheritance mode has been described in great danes with DCM?

Answer 58

Sex-linked mode in some families

Question 59

Name X criteria of malignancy for ventricular arrhythmias?

Answer 59

1. frequent paroxysmal or sustained VT (HR > 180/min) 2. Evidence of complexity (R-on-T-phenomenon, triplets, couplets, bigeminy, trigeminy) 3. Clinical signs of hemodynamic instability from arrhythmias 4. Polymorphic ventricular PMC (mroe concernning than monomorphic --> indicate multiple regions of disease within myocardium)

Question 60

Name 3 breeds are at risk for nutritionally mediated DCM?

Answer 60

1. Golden Retriever 2. American Cocker Spaniel 3. Newfoundland ## Footnote These breeds have been identified as having a higher susceptibility to the condition.

Question 61

What are 3 deficiencies/diets associated with nutritionally mediated DCM?

Answer 61

1. Taurine deficiency 2. L-carnitin deficiency (family of Boxers) 3. low-protein diets fed for prevention of urate urolithiasis in the Dalmatien ## Footnote Normal taurine concentrations do not rule out the disease.

Question 62

What are the taurine levels indicating deficiency in whole blood and plasma?

Answer 62

Whole blood <250 nmol/ml Plasma <60 nmol/L normal conc. does not rule out disease --> subset will have normal taurine concentrations but still respond to treatment ## Footnote These levels are critical for diagnosing taurine deficiency.

Question 63

Which breed family has been described with L-carnitine deficiency?

Answer 63

Boxers ## Footnote This deficiency has been specifically noted in a family of this breed.

Question 64

What type of diet is associated with nutritionally mediated DCM in Dalmatians?

Answer 64

Low-protein diets fed for prevention of urate urolithiasis ## Footnote Such diets may contribute to taurine deficiency.

Question 65

What types of diets have been implicated in causing nutritionally mediated DCM?

Answer 65

Grain-free, High contents of legumes and potatoes ## Footnote Diets produced by companies with less rigorous quality control standards are also a factor.

Question 66

What should be tested if the diet history matches DCM risk factors?

Answer 66

Whole blood and plasma taurine levels ## Footnote A diet change and empiric taurine and L-carnitine supplementation should follow.

Question 67

What are treatment options for nutritionally mediated DCM?

Answer 67

1. Change in diet 2. taurine supplementation (25kg: 500mg PO BID; > 25kg: 1000mg PO BID) 3. L-carnitine supplementation: 50mg/kg PO TID ## Footnote Dietary modification is essential in managing this condition.

Question 68

How does CHF affect the reversability of nutritionally mediated DCM?

Answer 68

Even in CHF still possibly reversible ## Footnote Response to therapy may be the best confirmatory test.

Question 69

True or False: A response to therapy is the best confirmatory test for nutritionally mediated DCM.

Answer 69

True ## Footnote Observing improvement can help confirm the diagnosis.

Question 70

What is the most common breed affected by Arrhythmogenic right ventricular cardiomyopathy?

Answer 70

Boxer ## Footnote Boxers are particularly predisposed to this condition.

Question 71

What histopathological findings are associated with Arrhythmogenic right ventricular cardiomyopathy?

Answer 71

Fatty + fibrofatty infiltration within the myocardium ## Footnote This infiltration affects the heart muscle's structure and function.

Question 72

What type of genetic mutation is involved in Arrhythmogenic right ventricular cardiomyopathy in Boxers?

Answer 72

Autosomal dominant mutation in striatin gene ## Footnote This mutation shows incomplete penetrance and variable expressivity.

Question 73

How does homozygosity for the striatin gene mutation affect the disease severity?

Answer 73

More severe disease (LV dilation, systolic dysfunction, L-CHF) ## Footnote Homozygous individuals typically exhibit more pronounced symptoms.

Question 74

What is the age of onset for ARVC in dogs?

Answer 74

6 years ## Footnote Early diagnosis is crucial for management.

Question 75

What are the three types of Arrhythmogenic right ventricular cardiomyopathy?

Answer 75

Type I: subclinical ventricular arrhythmias Type II: ventricular arrhythmias + syncope Type III: structural cardiac changes on echo +CHF ## Footnote Each type has distinct clinical presentations and severity.

Question 76

Where do ventricular arrhythmias typically originate in Arrhythmogenic right ventricular cardiomyopathy? How does this differ from structural changes?

Answer 76

origin: Right side structural: often left side --> L-CHF ## Footnote However, structural changes may involve the left side, leading to left-sided heart failure.

Question 77

Name 4 common clinical signs of ARVC?

Answer 77

1. Exercise intolerance 2. syncope 3. obtundation 4. sudden death ## Footnote These signs indicate serious implications for affected dogs.

Question 78

What ECG findings are associated with Arrhythmogenic right ventricular cardiomyopathy?

Answer 78

- Ventricular arrhythmias - SVTs - atrial fibrillation ## Footnote These findings are critical for diagnosis.

Question 79

How does a Holter monitor assessessment help in ARVC?

Answer 79

Assessment of severity + frequency of ventricular ectopy --> guidance of therapy ## Footnote This information helps guide antiarrhythmic therapy.

Question 80

What is the threshold of VPCs within a 24hr Holter that indicates a diagnosis of Arrhythmogenic right ventricular cardiomyopathy?

Answer 80

>300 VPCs ## Footnote 50-300 VPCs are considered equivocal for the disease.

Question 81

What does echocardiography and radiography typically reveal in cases of Arrhythmogenic right ventricular cardiomyopathy?

Answer 81

Often unremarkable Severe disease: Echocardigoraphy: DCM phenotype --> left-sided systolic dysfunction + LV enlargement radiography: cardiomegaly + sings of L-CHF ## Footnote In severe cases, it may show left-sided systolic dysfunction and LV enlargement.

Question 82

What are the treatment options for ARVC?

Answer 82

Sotalol 2-3mg/kg PO BID + mexiletine 5-8mg/kg PO TID --> combination possible for better control --> reduction of arrhythmias reduces clinical signs + improves QoL ## Footnote Both medications are effective at reducing the number of ventricular arrhythmias.

Question 83

What are negative prognostic indicators for dogs with ARVC?

Answer 83

- type III - homozygous striatin mutation status - L-CHF ## Footnote These factors significantly impact outcomes.

Question 84

List 5 secondary causes of LV hypertrophy

Answer 84

1. Systemic hypertension 2. Myocarditis 3. Cardiac neoplasia 4. Hyperadrenocorticism 5. Diabetes mellitus ## Footnote Each of these conditions can mimic or contribute to the appearance of HCM.

Question 85

In what breed does an inhereted form of canine HCM exist?

Answer 85

Pointer ## Footnote HCM can have a genetic basis and may run in families.

Question 86

What are the histological changes that occur with atrioventricular myopathy and its consequences?

Answer 86

Replacement fibrosis of atrial myocardium with or without fatty degeneration --> atrial dilation + persistent atrial standstill --> often progresses to involvement of ventricular myocardium ## Footnote This leads to atrial dilation and persistent atrial standstill.

Question 87

Which dog breeds are commonly affected by atrioventricular myopathy?

Answer 87

English Springer Spaniel, Labrador Retriever ## Footnote Other breeds may also be affected.

Question 88

What conditions are sometimes associated with atrioventricular myopathy?

Answer 88

* Myocarditis * Nemaline rod myopathy * Muscular dystrophy

Question 89

What are clinical signs related to bradycardia in atrioventricular myopathy?

Answer 89

* Lethargy * Syncope * Exercise intolerance * CHF

Question 90

What is the treatment for atrioventricular myopathy?

Answer 90

Permanent pacemaker

Question 91

What is the prognosis of atrioventricular myopathy with and without a pacemaker?

Answer 91

without: Poor with pacemaker: 866d (some up to 8y)