Large Animal Cardiology Flashcards
what is the range of normal heart rate in a horse?
23-48 bpm
what murmurs are common in horses?
soft (<=II/VI) systolic flow murmurs
how many heart sounds should you hear in horses?
two
three
four
all normal: not pathologic
how are cardiac murmurs described?
timing
intensity
point of maximum intensity
quality/pitch
what are some causes of diastolic murmurs?
aortic insufficiency: common
pulmonic insufficiency
what is accurately obtained with electrocardiography in large animals?
rate and rhythm only
what are the indications for an echocardiogram?
pre-purchase exam
evaluation of murmurs or arrhythmia
unexplained poor performance
in whom are radiographs most useful?
foals: both lateral and DV views can be taken
when is second degree AV block more concerning?
high grade or not responsive to exercise or anticholinergics
what is the most common cardiac rhythm disorder in the horse?
atrial fibrillation
what are the predisposing factors for atrial fibrillation?
concurrent high vagal tone and high sympathetic tone (cooling down post-race)
atrial enlargement
atrial stretch
which horses should you treat atrial fibrillation in?
performance horses with recent onset atrial fibrillation
no underlying cardiac disease
what can you use to treat ventricular tachycardia?
lidocaine
propanolol
sotalol or amiodarone
magnesium sulfate
what valve regurgitation is common in middle-aged or older horses?
mitral and aortic regurgitation
what is the range of normal heart rate for a horse?
23-48
where is the mitral valve on a horse?
level of elbow
where is the aortic valve on a horse?
craniodorsal of mitral
what are some causes of systolic ejection murmurs?
innocent
fever
anemia
VSD or ASD
aortic stenosis (rare)
pulmonic stenosis (rare)
what does it mean for something to be a category B activation pattern?
depolarization of ventricles in single burst
more diffuse penetration of purkinje fibers
when might you see a globoid heart in a horse?
pericardial effusion
pericarditis
when is cardiac troponin-I documented to be elevated in horses?
myocardial necrosis
ruptured aortic jet lesion
piroplasmosis
endurance exercise
sepsis
is ventricular tachycardia common in horses?
no
who is third degree AV block common in?
jerusalem donkeys
young animals: congenital
when is paroxysmal atrial fibrillation seen?
racehorses up to 24 hours post race
is atrial fibrillation usually seen with other cardiac pathology?
not in large horses
more in ponies
what can be the heart rate with ventricular arrhythmias?
can exceed 100
what are some lidocaine side effects in horses?
neurologic side-effects: seizures, ataxia, CNS depression (also cats)
increased defibrillation threshold
suppression of escape rhythms
what can be found of physical exam with aortic regurgitation?
variable intensity, cooing, descrendo holodiastolic murmur
hyperdynamic pulses
what happens with aortic insufficiency with age?
acquired lesions increase with age
is intensity of the murmur a good guide to the severity of aortic insufficiency?
no
arterial pulse quality better indicator
what are some clinical signs of endocarditis?
new murmur
intermittent or persistent fever
tachycardia
tachypnea
how can you diagnose endocarditis?
clinical signs
elevated WBC, fibrinogen, globulins, +/- troponin I
anemia of chronic disease
positive blood culture
echocardiography
what is the prognosis of endocarditis?
poor to guarded for performance and long-term survival
what is there often a history of with pericardial disease?
respiratory disease
what are the etiologies of pericarditis?
idiopathic
infectious
neoplasia
aseptic
what are some infectious causes of pericarditis?
bacterial
viral
eastern tent caterpillar (mare reproductive loss syndrome)
what is the prognosis of pericarditis?
good if infectious and known pathogen
how common is primary cardiomyopathy in large animals?
rare
who is predisposed to ruptured sinus of valsalva?
breeding stallions
who is predisposed to aorto-pulmonary fistula?
friesians
who are congenital defects more common in?
arabs
standardbreds
welsh mountain ponies
some breeds of cattle
what is the most common congenital heart defect?
ventricular septal defect
where are ventricular septal defects usually located?
membranous portion of interventricular septum just beneath aortic valve
where is the pulmonic PMI in a horse?
cranial, slightly lower than aortic
how is the point of maximal intensity described?
left vs right
base vs apex
what are some regurgitant causes of systolic murmurs?
mitral regurgitation
tricuspid regurgitation
how do you place the base apex lead?
right leads right jugular furrow
left leads left apex
what can you look for with radiographs for heart failure?
pleural effusion
pulmonary edema
are isolated premature beats in horses treated?
no
what type of atrial fibrillation is most common in horses?
persistent
what does atrial fibrillation require to start and maintain it?
trigger to start
substrate to maintain
should all horses with atrial fibrillation be treated?
not necessary in those that do not have to be high level athletes
do not convert those with primary cardiac disease
how is quinidine sulfate given?
through NG tube
what does quinidine sulfate do?
negative inotrope
positive chronotrope
hypotensive
what is ventricular tachycardia associated with in horses?
severe electrolyte disorders
drug reactions
hypoxia
myocarditis
underlying heart disease
myocardial infarction
toxicity
what signs are associated with severely affected animals with acquired valvular disease?
reduced athletic performance
exercise intolerance
respiratory distress
syncope or collapse
what can the pericarditis be?
effusive
fibrinous
constrictive
what are the secondary causes of cardiomyopathy?
myocarditis
ionophore toxicity
vitamin E/selenium or copper deficiency
cantharidin toxicity
neoplasia: lymphoma
what murmurs are normal in foals?
less than 3 days old: continuous murmurs
2 months: soft systolic murmurs
