K9 Myocardial Diseases Flashcards
Dilated Cardiomyopathy (DCM)
Common cardiac dz
Large and giant breeds and cocker spaniel
Male, middle aged to older (4-10y)
Possible causes of DCM
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)
Pathophysiology of DCM
Systolic pump failure
MR secondary
Diastolic failure
Arrhythmias
L-CHF and biventricular failure
Gross pathology of DCM
Moderate to marked dilation of 4 chambers (left heart more severely)
Myocardium thin, pale and flabby
Thin papillary muscles
CS associated with DCM (advancing order)
No CS → exercise intolerance, syncope, resp. distress, abdominal distension, WL (cachexia) →
Sudden death (20-30% boxers and dobermans)
Genotypic stage of DCM
Normal heart
No CS
Occult stage of DCM
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
Overt stage of DCM
Abnormal heart
CS: heart failure and arrhythmias
Sinus tachycardia, a fib and ventricular tachycardia
PE on a pet with DCM
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
DX DCM
NT-proBNP elevated or normal with occult DCM
unnecessary if murmur present
What else is seen with ECG rhythms (DCM)
LVE and LAE (tall R waves and wide P waves)
Conduction disturbances
Small complexes with pleural effusion
Thoracic radiographs associated with DCM
Generalized cardiomegaly
Pulm. venous congestion, pulm edema and pleural effusion
Chronic oral therapy management of DCM
Diuretics, Ionotropes and ACE-1,
anti- arrhythmia drugs if needed
Stacked drugs: diuretics, vasodilators
Emergent therapy for DCM
Oxygen, IV Lasix, dobutamine, nitroprusside,
Prognosis for DCM
Poor to guarded
Hours to 2 yrs
DCM in Dobermans
2 causative genetic mutations: pyruvate dehydrogenase kinase (DCM1 and DCM2)
Risk highest with both mutations
Prevalence of DCM in Dobermans
45-63%
Adult onset (acquired)- 2-15 yrs of age
Ventricular arrhythmias: 90%
Sudden death: 30-50%
T/F: L-CHF more common than biventricular failure with DCM in Dobermans
TRUE
Occult stage of DCM in Dobermans
Long (2-4 yrs)
Screen with echo and Holter monitoring: systolic dysfunction
Tx of DCM for Dobermans
Pimobendan if systolic dysfunction
Mexiletine or sotalol for ventricular arrhythmia
DCM in large breed dogs
Irish wolfhounds, great danes, newfoundlands
Inherited, sudden death possible
CHF and a fib.
Juvenile DCM
Portuguese water dogs
Normal @ birth then systolic dysfunction develops at 8-10w
Rapid progression to CHF then death @ 14-20w
Arrhythmogenic right ventricular cardiopathy (ARVC)
Inherited dz in boxers (+ english bulldogs) @ 6y
RV most affected and electrical system
ARVC pathophysiology
Replacement of myocardium by fat and fibrous tissue
Ventricular arrhthymias (syncope, sudden death)
Symptoms ARVC
Asymptomatic with VPCs (m-y)
Syncope, resp. distress, abdominal distention (m-y)
Ventricular dilation and myocardial failure (CHF)
Sudden death possible
DX ARVC
Genetic test: striatin a desmosomal protein
ECG: upright VPCs in lead 2
What does an echocardiography show with ARVC?
Can be normal
Systolic dysfunction, ventricular dilation, atrial enlargement
Tx of ARVC
Ven. tachy: sotalol, mexiletine
CHF: furosemide, pimobendan, ACE-1
Nutritional cardiomyopathy
Taurine deficiency: Genetic predisposition in cocker spaniels and goldens
Dx of Nutritional cardiomyopathy
Echo: systolic dysfunction
Measure plasma or serum taurine levels (low)
Thoracic rads if CS of CHF
Tx of Nutritional cardiomyopathy
Taurine supplementation
Positive ionotropes
Manage CHF
What diet is associated with nutritional cardiomyopathy
Boutique, exotic, grain free diets (BEG diets)- linked to some goldens
Prognosis of Nutritional cardiomyopathy
Improve or normalize with diet change and temporary or long-term taurine supplementation
Myocarditis
Trauma, infectious or immune dz of myocardium
Infectious myocarditis more common
What causes myocarditis
Radiation, heat stroke, hypothermia, trauma
Parvo
Trpanosoma cruzi (Chagas’ dz)
Toxoplasma
Neospora
Sepsis/ endocarditis
Borrelia burgdorferi
Bartonella spp.
Infectious myocarditis
Parvo: young puppies, acute to peracute death
Protozoal: Arrhythmias and R-CHF in chr. stage
Hx and CS of infectious myocarditis
Atypical signalment
Exercise intolerance, lethargy, syncope, sudden death
CHF without known cardiac dz
Arrhythmias and ADR
Dx of infectious myocarditis
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
Doxorubicine (adriamycin) toxicity
Systolic dysfunction, conduction disturbances, arrhythmias
If cumulative dose >240 mg/m
Tachycardia-induced cardiomyopathy
Caused by HR > 180 bpm for 2-3w
Infiltrative cardiomyopathy
Lymphoma
Hypertrophic cardiomyopathy
Rare in dogs
Dalmations predisposed
