K9 Myocardial Diseases

Question 1

Dilated Cardiomyopathy (DCM)

Answer 1

Common cardiac dz
Large and giant breeds and cocker spaniel
Male, middle aged to older (4-10y)

Question 2

Possible causes of DCM

Answer 2

Familial or genetic (cytoskeletal proteins)- Boxer, doberman and PWD
Immune-mediated (B-receptor, a, B-MHC, ADP-ATO translocator protein)
Taurine deficiency (cocker, goldens)
Carnitine deficiency (boxers)

Question 3

Pathophysiology of DCM

Answer 3

Systolic pump failure
MR secondary
Diastolic failure
Arrhythmias
L-CHF and biventricular failure

Question 4

Gross pathology of DCM

Answer 4

Moderate to marked dilation of 4 chambers (left heart more severely)
Myocardium thin, pale and flabby
Thin papillary muscles

Question 5

CS associated with DCM (advancing order)

Answer 5

No CS → exercise intolerance, syncope, resp. distress, abdominal distension, WL (cachexia) →
Sudden death (20-30% boxers and dobermans)

Question 6

Genotypic stage of DCM

Answer 6

Normal heart
No CS

Question 7

Occult stage of DCM

Answer 7

Abnormal heart and no CS
May last years, sudden death may be first CS
ID of this stage is important
Sinus arrhythmias and sinus with VPC singlet

Question 8

Overt stage of DCM

Answer 8

Abnormal heart
CS: heart failure and arrhythmias
Sinus tachycardia, a fib and ventricular tachycardia

Question 9

PE on a pet with DCM

Answer 9

Tachycardia/ tachypnea, pulse deficits and weak femoral pulses
Soft systolic murmur, S3 gallop
Jug venous distension, abdominal distension with fluid, harsh resp sounds and cool extremities

Question 10

DX DCM

Answer 10

NT-proBNP elevated or normal with occult DCM
unnecessary if murmur present

Question 11

What else is seen with ECG rhythms (DCM)

Answer 11

LVE and LAE (tall R waves and wide P waves)
Conduction disturbances
Small complexes with pleural effusion

Question 12

Thoracic radiographs associated with DCM

Answer 12

Generalized cardiomegaly
Pulm. venous congestion, pulm edema and pleural effusion

Question 13

Chronic oral therapy management of DCM

Answer 13

Diuretics, Ionotropes and ACE-1,
anti- arrhythmia drugs if needed
Stacked drugs: diuretics, vasodilators

Question 14

Emergent therapy for DCM

Answer 14

Oxygen, IV Lasix, dobutamine, nitroprusside,

Question 15

Prognosis for DCM

Answer 15

Poor to guarded
Hours to 2 yrs

Question 16

DCM in Dobermans

Answer 16

2 causative genetic mutations: pyruvate dehydrogenase kinase (DCM1 and DCM2)
Risk highest with both mutations

Question 17

Prevalence of DCM in Dobermans

Answer 17

45-63%
Adult onset (acquired)- 2-15 yrs of age
Ventricular arrhythmias: 90%
Sudden death: 30-50%

Question 18

T/F: L-CHF more common than biventricular failure with DCM in Dobermans

Answer 18

TRUE

Question 19

Occult stage of DCM in Dobermans

Answer 19

Long (2-4 yrs)
Screen with echo and Holter monitoring: systolic dysfunction

Question 20

Tx of DCM for Dobermans

Answer 20

Pimobendan if systolic dysfunction
Mexiletine or sotalol for ventricular arrhythmia

Question 21

DCM in large breed dogs

Answer 21

Irish wolfhounds, great danes, newfoundlands
Inherited, sudden death possible
CHF and a fib.

Question 22

Juvenile DCM

Answer 22

Portuguese water dogs
Normal @ birth then systolic dysfunction develops at 8-10w
Rapid progression to CHF then death @ 14-20w

Question 23

Arrhythmogenic right ventricular cardiopathy (ARVC)

Answer 23

Inherited dz in boxers (+ english bulldogs) @ 6y
RV most affected and electrical system

Question 24

ARVC pathophysiology

Answer 24

Replacement of myocardium by fat and fibrous tissue
Ventricular arrhthymias (syncope, sudden death)

Question 25

Symptoms ARVC

Answer 25

Asymptomatic with VPCs (m-y) Syncope, resp. distress, abdominal distention (m-y) Ventricular dilation and myocardial failure (CHF) *Sudden death possible*

Question 26

DX ARVC

Answer 26

Genetic test: striatin a desmosomal protein ECG: upright VPCs in lead 2

Question 27

What does an echocardiography show with ARVC?

Answer 27

Can be normal Systolic dysfunction, ventricular dilation, atrial enlargement

Question 28

Tx of ARVC

Answer 28

Ven. tachy: sotalol, mexiletine CHF: furosemide, pimobendan, ACE-1

Question 29

Nutritional cardiomyopathy

Answer 29

Taurine deficiency: Genetic predisposition in cocker spaniels and goldens

Question 30

Dx of Nutritional cardiomyopathy

Answer 30

Echo: systolic dysfunction Measure plasma or serum taurine levels (low) Thoracic rads if CS of CHF

Question 31

Tx of Nutritional cardiomyopathy

Answer 31

Taurine supplementation Positive ionotropes Manage CHF

Question 32

What diet is associated with nutritional cardiomyopathy

Answer 32

Boutique, exotic, grain free diets (BEG diets)- linked to some goldens

Question 33

Prognosis of Nutritional cardiomyopathy

Answer 33

Improve or normalize with diet change and temporary or long-term taurine supplementation

Question 34

Myocarditis

Answer 34

Trauma, infectious or immune dz of myocardium Infectious myocarditis more common

Question 35

What causes myocarditis

Answer 35

Radiation, heat stroke, hypothermia, trauma Parvo Trpanosoma cruzi (Chagas' dz) Toxoplasma Neospora Sepsis/ endocarditis Borrelia burgdorferi Bartonella spp.

Question 36

Infectious myocarditis

Answer 36

Parvo: young puppies, acute to peracute death Protozoal: Arrhythmias and R-CHF in chr. stage

Question 37

Hx and CS of infectious myocarditis

Answer 37

Atypical signalment Exercise intolerance, lethargy, syncope, sudden death CHF without known cardiac dz Arrhythmias and ADR

Question 38

Dx of infectious myocarditis

Answer 38

ECG: tachy and bradyarrhythmias, AV block Echo: systolic dysfunction, eccentric hypertrophy and pericardial effusion Cytology of effusion, CBC/ chem, blood smear, serology, cardiac troponin 1 level

Question 39

Doxorubicine (adriamycin) toxicity

Answer 39

Systolic dysfunction, conduction disturbances, arrhythmias If cumulative dose >240 mg/m

Question 40

Tachycardia-induced cardiomyopathy

Answer 40

Caused by HR > 180 bpm for 2-3w

Question 41

Infiltrative cardiomyopathy

Answer 41

Lymphoma

Question 42

Hypertrophic cardiomyopathy

Answer 42

Rare in dogs Dalmations predisposed