CBL 5: The Coughing Cavalier

What model can be applied to a veterinary consultation?

calgary cambridge model

What are the 5 steps of the calgary cambridge model?

initiating the session, gathering info, physical exam, explanation and planning, closing session

How can rapport be built with new clients? (5 examples)

consent, empathetic, listen, be honest, discuss potential risks

What is the physiological purpose of coughing?

clear secretions and particulates from the airways and protects inhalation of foreign materials

What are the 3 phases of the cough response?

inspiratory, compression and expiratory

What happens during phase 1 of the cough response?

inhalation

What happens during the phase 2 of the cough response?

forced exhalation against a closed glottis

What happens during phase 3 of the cough response?

opening of glottis and release of air from the lungs

clinical syndrome

a collection of physical exam findings, signs, symptoms or history caused by a disease

Discrete disease process

the pathophysiological response to an internal or external factor

What is the cause of myxomatous mitral valve disease?

myxomatous degeneeration of mitral valves

cardiac hypertrophy

walls of the heart's ventricles thicken

What does myxomatous mitral valve disease cause?

regurgitation of blood from the ventricle into the atrium

What could be the most likely cause of coughing in a dog with myxomatous mitral valve disease?

early stages of congenital heart failure

Why does congenital heart failure cause coughing?

blood backs up in blood vessels in lungs causing excess fluid in capillaries to leak into airways, excess fluid causes irritation due to inflamed airways

Where do impulses travel via in a cough?

internal laryngeal nerve to medulla

During a cough reflex, where do messages from the cerebral cortex and medulla travel?

via vagus and superior laryngeal nerves to glottis, external intercostals, diaphragm, etc.

Where are cough receptors located?

larynx to bronchi

Where is the cough centre located?

medulla oblongata (of the brainstem)

Stroke volume (SV)

amount of blood pumped out of the ventricle in one heart beat

SV =

EDV - ESV

ejection fraction

proportion of blood pumped out of the ventricle in one heart beat

ejection fraction =

(EDV-ESV)/EDV

regurgitant stroke volume

amount of blood pumped out of the ventricle along the aorta/pulmonary artery to the body/lungs in one heart beat

total stroke volume =

regurgitant stroke volume + forward stroke volume

cardiac output

amount of blood pumped out of the heart per unit of time

cardiac output =

forward stroke volume x HR

systemic blood pressure

pressure of the blood on the walls of the systemic blood vessels (usually refers to arterial pressure rather than venous)

systemic blood pressure =

CO x systemic vascular resistance

Where can the left atrio-ventricular valve be heard most clearly in a dog?

5th intercostal space

Where can the aortic valves be heard most clearly in a dog?

4th intercostal space (at shoulder level)

Where can the pulmonary valves be heard most clearly in a dog?

left 3rd intercostal space (above the costochondral junction)

What are the normal heart sounds?

S1 and S2

What the is S1 heart sound associated with?

closure of AV valves

What is the S2 heart sound associated with?

closure of semilunar valves

List the heart sounds normally audible in the dog

lub dub (S1 and S2)

List the heart sounds normally audible in the horse

lub dub S1 and S2 (sometimes S3 and S4 but not as loud)

What detects changes in blood pressure?

baroreceptors

What does a decrease in systemic blood pressure stimulate kidneys to release into the blood?

renin enzyme

What does the liver produce when systemic blood pressure decreases?

angiotensinogen proteins

What is one of the parts that angiotensinogen protein divides into?

angiotensin I

What enzyme further divides angiotensin I?

angiotensin-converting enzyme (ACE)

Is angiotensin I an inactive or active hormone?

inactive

What does ACE further divide angiotensin I into?

angiotensin II

Is angiotensin II an active or inactive hormone?

active

What does angiotensin II activation trigger?

constriction of arteriole walls and release of aldosterone and ADH

What does constriction of arteriole walls, release of aldosterone and ADH result in?

increased blood pressure

What releases aldosterone?

adrenal glands

What releases ADH?

pituitary gland

How do aldosterone and ADH cause increased blood pressure?

cause kidneys to retain Na ions which increases Na conc and water retention

What does the Frank-Starling relationship state?

ventricular output increases as preload (EDV) increases

What does the stroke volume of the heart increase in response to? (Frank-Starling law)

increase in blood vol in ventricles at the end of diastole

What does the starling equation show?

balance of hydrostatic and oncotic pressures across a capillary bed (determines net fluid balance)

What effect does cardiac diseases have on the starling equation (fluid balance)

increased LA pressure leads to increase in pul venous pressures, disruption in fluid balance across capillary bed causing accumulation of fluid in the interstitium

What does CIRD stand for?

canine infectious respiratory disease (AKA kennel cough)

What are the common causative agents of CIRD?

Bordetells bronchiseptica, parainfluenza virus, adenovirus, canine distemper virus, canine influenza virus et

What are infections involving the distemper virus, mycoplasma species or canine influenza more likely to progress to?

pneumonia

How can bordetella immunisation be administered via/

injection or intranasal vaccine

How would you manage a dog with suspected kennel cough in a hospital environment?

prevention and control using vaccine, isolation, PPE, hygiene, ventilation

What non-core vaccines should be used for dogs at risk of an outbreak in kennels?

parainfluenza and bordetella

What is the kV (kilovoltage)? (radiograph)

the energy of each photon emitted

What does a higher kV mean? (for radiography)

higher degree of penetration of the beam and higher degree of scatter

What is the mAs (milliampereseconds)? (radiographs)

number of photons emitted (current x time)

What does lower mAs mean?

shorter exposure times

what does collimation do? (radiography)

reduces size of radiation beam and focuses on one body part (better image quality), less scatter

What properties do x-rays and gamma-rays share?

high frequencies, short wavelengths, high energy

How are gamma rays produced?

from excited nucleus of an atom that has just undergone radioactive decay

How are x-rays produced?

when electrons in an atom are repositioned

What is needed to block x-rays and gamma-rays penetration?

thick sheets of lead or concrete

Line voltage compensator (radiography)

ensures consistent output of voltage

activator for a moving grid (radiography)

reduce artifacts - improving quality of image

automatic exposure control (radiography)

small radiolucent detectors built into the x-ray table that automatically turn off the x-ray beam when enough x-rays have passed through it

What are the 2 ways x-rays are attenuated?

absorption and scattering

What do anti-scatter grids improve?

contrast of an x-ray image

How to grids improve the contrast of an x-ray image?

by rejecting scattered x-rays

What do grids do?

only allow x-rays travelling parallel to the main beam to pass through

What does CR stand for?

computed radiography

What does DR stand for?

digital radiography

What does computed radiography (CR) use?

specialised cassette and image reading device

What does the cassette in computed radiography contain?

photostimulable phosphor plate which absorbs x-rays

what is the cassette replaced by in digital radiography?

a digital imaging sensor

What are some difficulties in obtaining radiographic images of diagnostic quality in conscious animals?

excessive movement causes blurry images that are difficult to interpret

What is usually needed to obtain radiographic images of animals?

sedation

pulse deficit

when the pulse rate is less than the heart rate

What can result in pulse deficits?

premature cardiac contractions

What can premature cardiac contractions result in?

pulse deficits

Why do premature cardiac contractions result in pulse deficits?

disrupt heart rhythm, extra beats less effective at pumping blood around the body

aortic trifurcation

continuation of aorta to internal iliacs and tail and left and right external iliacs

What are the 3 laws of inheritance?

1. dominance and uniformity

2. segregation

3. independent assortment

Who determined the 3 laws of inheritance?

Gregor Mendel

What does Mendel’s law of dominance and uniformity state?

characteristics come in multiple forms and one allele will mask the effect of the other

homozygous

both copies of the allele are the same

heterozygous

two different copies of the allele

What does Mendel’s law of segregation state?

during gamete formation, the alleles from each gene segregate from each other so that each gamete carries only one allele for each gene

What does Mendel’s law of independent assortment state?

alleles of one character segregate independently of the other character

inherited

a genetic abnormality that has been passed down from one/both parents

congenital

an abnormality that you are born with (not necessarily genetic in origin)

thrombus

blood clot that forms in the circulatory system

embolus

a part of a thrombus that breaks off and travels through the vasculature until it becomes lodged

What factors can predispose to thrombus formation (Virchow’s triad)

endothelial injury, stasis of blood flow and hypercoagulability