Test 1: lecture 18: canine Flashcards
primary myocardial disease
Idiopathic or heritable disorders resulting in structural or functional abnormalities of the heart muscle
* Cardiomyopathies
secondary myocardial disease
inflammatory, metabolic, toxic or infiltrative disease of the myocardium with a known etiology or causative agent
* May or may not be reversible
two primary myocardial diseases
dilated cardiomyopathy (DCM)
Arrhythmogenic right ventricular cardiomyopathy (ARVC)
two secondary myocardial diseases
nutritional cardiomyopathy (taurine)
myocarditis
secondary dilated cardiomyopathy can be caused by
Nutritional factors – taurine, carnitine, other
* Toxins – chemotherapy
* Infection/inflammation – myocarditis
* Arrhythmias – chronic tachycardia
* Endocrine disease – hypothyroidism
— is Myocardial disease characterized by systolic dysfunction and secondary cardiac chamber dilation
dilated cardiomyopathy
what does heart with primary DCM look like
eccentric hypertrophy (thin walls- stretched out)
all four chambers but left>right
papillary muscles can be atrophies
heavy heart
histopath of DCM
- Attenuated wavy fibers
- Fibrofatty infiltration
- Myocyte atrophy/necrosis
- Minimal inflammation
DCM will lead to — stroke volume and — chambers
reduced
dilated
(impaired systolic function- reduced contractility)
what kind of failure will DCM cause
foward (poor ejection)
reduced cardiac output, hypotension → weakness and exercise intolerance
backward failure (congestion)
elevated ventricular end-diastolic pressure, high atrial pressures, high pulmonary venous pressure →CHF
what kind of dogs get DCM
large and giant male breeds
- Doberman Pinscher
- Boxer (ARVC)
- Giant breeds (GD, Newfie, Irish Wolfhound)
Exceptions: PWD, Manchester Terrier, Cocker Spaniel
Adults except PWD, Manchester Terrier (juvenile DCM)
clinical signs of DCM
from low output: weakness, lethargy, exercise intolerance, syncope, death
from congestion: cough, dyspnea, Orthopnea, insomnia, Abdominal distension, Anorexia, weight loss, Cardiac cachexia
why can you hear S3 with dog with DCM
ventricles do not fully empty (low output)
therefore when blood from atria pushed into ventricle will make a murmur
PE of dog with DCM
- Arrhythmia
- Pulse deficits
- Gallop heart sound (S3)
- Soft murmur (AV valves)
- Weak pulses
- Cold extremities
- Tachypnea, dyspnea
- Jugular distension, ascites
EKG of DCM
LV enlargement pattern
* Tall R wave
* Prolonged QRS duration (mild)
LBBB
* Prolonged QRS duration
Atrial enlargement pattern
* Increased P wave duration (P-mitrale)
* Increased P wave amplitude (P-pulmonale)
75% will get Afib
VPC
with ventricular tachycardia
Afib
75% of dogs with DCM will also have Afib
Xray of DCM
cardimegaly: left sided or generalized
left sided CHF
* distended pulmonary veins
* pulmonary edema : perihilar to caudodorsal, intersitial to alveolar
right sided CHF
* distended caudal vena vava
* pleural effusion
* ascites
DCM
large left atrium and ventricle (double opasity on VD)
diffuse perihilar and caudodorsal pulmonary edema
how to measure systolic function on echo
fractional shortening
ejection fraction
stages of DCM
stage 1: normal Heart, no signs
stage 2 occult: abnormal heart, no signs
stage 3 overt: abnormal heart with clinical signs/CHF
—% of dobermans have DCM
50-60
occurs in males 4-10 years old
sudden onset with syncope and CHF
DCM in dobermans
50-60% of all males 4-10 years old
sudden onset of symptoms: syncope and CHF
ventricular arrythmia more common then Afib
sudden death (VT→VF) 30-50%
CHF made worse by AFib
what genetic mutation in dobermans with DCM
autosomal dominant
incomplete, age related penetrance
PDK4 (DCM1)
DCM2
both mutations = 30% increased risk
PDK4( DCM1) encodes for
Encodes mitochondrial protein pyruvate
dehydrogenase kinase 4
- PDK4 has an important role in cardiac energy metabolism
DCM in dobermans
DCM2 codes for
- Encodes sarcomeric protein titin
- Titin contributes to active contraction, passive stiffness
21% risk increase
DCM in dobermans
testing in dobermans for DCM
annual echo and holter starting at 3 years old
genetic testing (NCSU) for PDK4 and DCM2
boxers with advanced — can develop DCM
ARVC
DCM is — in great danes
x linked
with Afib more common then Vtach
DCM in newfoundlands and irish wolfhounds is —
autosomal dominant
with Afib more common then Vtach
what causes DCM in cocker spaniels
inherited?
diet?
unknown
what two dogs get juvenile DCM
portugese water dogs (2-32 weeks old), autosomal recessive
Toy machester terrier (10 weeks-1 year old), autosomal recessive, K channel, complete penetrance
how to treat preclinical DCM
pimobendan (inodilator)
how to treat clinical stage of DCM
pimobendan
diuretic
ACE inhibitor
spironolactone
how to treat ventricular arrhythmias in DCM
sotalol, mexiletine, amiodarone
used for VPCs or Vtach
how to treat supraventricular arrhythmias in dogs with DCM
AFib
diltiazem, digoxin
what did protect study show
DCM study in dobermans
pimobendan prolonged survival and kept dogs asymptomatic for an extra 9 months
outcome of DCM in different dog breeds
mean survival 6-9 months
ARVC is common in
boxers, english bulldogs, cats and humans
ARRHYTHMOGENIC RIGHT VENTRICULAR CARDIOMYOPATHY (ARVC)
how is ARVC inherited
autosomal dominant mutation in Striatin (ARVC1) and ARVC 2
what does ARVC do
attacks desmosomes that hold cardiac cells together
causes mechanical and electrical uncoupling
atrophy of cells and replacement by fibrofatty tissue
scar tissue from ARVC causes
arrhythmias: VPCs, Vtach → right ventricle origin
systolic failure → heart failure →fainting and sudden death (40%)
ARVC will lead to — in 40% of cases
sudden cardiac death
what genes for ARVC in boxers
autosomal dominant
Striatin (ARVC 1)
* Colocalizes to intercalated disk
* Homozygotes - higher risk of severe disease (DCM phenotype)
ARVC 2
* SNP in a regulatory gene
what happens to english bulldogs with ARVC
no gene found yet but happens more often in males
most will get CHF instead of arrhythmias
Sotalol is treatment of choice for — arrhythmias
in Boxers
ventricular
ARVC (will get ventricular arrhythmias (VPC and Vtach), syncope, sudden death and CHF)
what are some things that cause nutritional cardiomyopathy
- Taurine deficiency
- L-carnitine deficiency
- Boutique, exotic ingredient, grain-free (BEG) diets
can be reversible
what breeds can develop taurine deficiency?
cocker spaniel
golden
newfoundland
dogs can make taurine, cats can not
found in seafood and meat
how to diagnose taurine deficiency
paired (whole and plasma) taurine levels
if low supplement
— helps transport fatty acids into mitochondria for beta oxidation
L- carnitine
found in red meat and dairy or synthesized in skeletal and cardiac muscle
why is diagnosis of L carnitine deficiency hard
normal levels could be false positive
carnitine found in red meat, dairy or synthesized in skeletal and cardiac muscle
helps transport fatty acids into mitochondria for beta oxidation
some causes of myocarditis
parvo
trypanosoma
how to diagnose myocarditis
high troponin
infectious disease screening
echo with low EF
ECG with arrhythmias
post mortem
