Equine Cardio Flashcards
What heart sounds do you ear in a horse?
S1, S2, S3, S4
all are normal
What is a split S1 sound?
you hear the AV valves shut at different times - large heart with ventricles emptying at different rates
S3
passive filling of the ventricle
Normal Horse Heart Rate
24-40bpm
Normal Foal Heart Rate
60-80bpm
How is vagal tone related to heart rate in horses?
vagal tone decreases heart rate
Sympathetic tone effect on heart rate?
increases heart rate
Is heart rate affected by level of fitness in horses?
no
Reasons HR increases in horses
excitation, fatigue, pain, cardiac abnormality, illness
Ways to Measure Heart Rate
stethoscope
ECG
HR monitors/cell phone apps
Does pain increase heart rate?
yes
Is recovery rate affected by level of pain?
Yes - slower to recover if painful, d/t increased HR and RR
Does HR increase wth different horse gaits?
yes
Maximum HR in horses
220-240bpm
Does HR have an effect on length of life in horses?
not that we know of
How quickly should heart rate decrease after exercise?
by 50% within 30 seconds
Cardiac output
heart rate times stroke volume
resting stroke volume in horses
1 liter
What percent of a horses body weight is blood volume?
8%
How much of their blood can a horse pump in one minute?
100%
stroke volume
amount of blood pumped by the heart in a single beat
Does stroke volume change during exercise?
Not by much if at all
Do larger hearts have larger stroke volumes?
yes
Best indicator of aerobic capacity?
Maximal oxygen consumption (V O2 max)
Fick principle
maximal oxygen consumption is stroke volume times the difference in amount of oxygen between the arteries and veins
How much of a horse’s RBCs are stored in the spleen?
30-35%
What is a horse’s PCV during exercise?
55-65%
What is a horse’s PCV at rest?
30-45%
Does spleen size vary by breed?
yes
Does heart weight vary by breed?
yes
Bohr shift
when you exercise, your temp inc., CO2 inc., pH increases –> curve of hemoglobin saturation moves to the right
Exercise Induced Pulmonary Hemorrhage
capillaries are easily ruptured in conditions of high pressure
Does blood pressure increase with exercise?
yes
What balances out the increase in blood pressure during exercise?
total peripheral resistance (increases blood flow and oxygen delivery to exercising muscles)
If not heart attacks, what more than likely causes sudden death in horses?
various arrhythmias (venticular fibrillation)
