Have a Heart: Valves & Murmurs
You’re ausculting a small breed dog and hear a left side murmur.
a) Which valves could be affects affected?
b) In which intercostal space is affected
describe (3) locations and name that are affected on left side
a) Mitral valve (or pulmonary or aortic)
b) Left 3,4, 5th intercostal space
A dog with protein-losing enteropathy has marked hypoalbuminemia and pitting limb edema.
a) Which Starling force is primarily decreased?
b) How does this change promote edema formation?
a) Plasma oncotic (colloid osmotic) pressure.
b) Lower oncotic pressure reduces fluid reabsorption from interstitium back into capillaries, leading to net filtration and interstitial fluid accumulation (edema).
On an ECG from a normal dog:
a) Name a wave
b)what does this wave represent
a) The R wave
b) The deflection becomes predominantly positive / tall upright, because depolarization moving toward the positive lead creates an upward deflection.
Which blood gas usually has the biggest effect on how fast an animal breathes: oxygen (O₂) or carbon dioxide (CO₂)?
Carbon dioxide (CO₂) has the biggest effect on breathing rate.
You’re passing a nasogastric tube in a horse.
a) Which nasal meatus should you direct the tube through?
b) Why is this route preferred over the others?
a) The ventral nasal meatus.
b) It provides the safest, most direct route to the nasopharynx, avoiding the fragile ethmoid turbinates and decreasing the risk of bleeding.
In a dog with mitral regurgitation, S1 and S2 are heard, but there is a “whoosh” between them.
a) During which phase of the cardiac cycle is the regurgitation occurring?
b) Briefly describe the mechanical problem at the valve that produces this sound.
a) Systole – during ventricular contraction.
b) The mitral valve is incompetent, so when the left ventricle contracts, blood leaks backward into the left atrium, creating turbulent flow and a systolic murmur.
A cow with right-sided heart failure develops brisket edema.
a) Which Starling force is increased at the systemic capillaries?
b) How does impaired lymphatic drainage contribute to this edema?
a) Capillary hydrostatic pressure is increased due to venous congestion.
b) Lymphatics normally return excess fluid/protein; when overwhelmed or compressed, they can’t keep up, so interstitial fluid accumulates, worsening brisket edema.
A Doberman pinscher presents with mucosal bleeding and prolonged bleeding time but normal platelet count.
a) Which protein is most important for platelet adhesion to exposed subendothelium in primary hemostasis?
b) This protein binds to a specific platelet glycoprotein receptor. Name that receptor.
a) von Willebrand factor (vWF).
b) Glycoprotein Ib (GpIb).
During exercise, several factors shift the oxyhemoglobin dissociation curve.
a) Does increased temperature and CO₂ shift the curve left or right?
b) How does this shift help working muscles?
a) It shifts the curve to the right.
b) A right shift facilitates O₂ unloading at the tissues, so working muscles get more oxygen.
A dog with rhinitis is sneezing frequently, while a dog with tracheitis mostly coughs.
a) Which airway region is mainly involved in sneezing vs coughing?
b) Explain why these two different reflexes are triggered.
a) Sneezing – upper respiratory tract (nasal cavity).
Coughing – lower respiratory tract (trachea/bronchi).
b) Local irritation of receptors in the URT triggers sneezing to clear nasal passages; irritation in the LRT triggers coughing to expel material from lower airways.
You’re evaluating a heart specimen.
a) The chordae tendineae connect which two structures?
b) Functionally, why is rupture of these structures dangerous during systole?
a) They connect AV valve to the papillary muscles.
b) They prevent valve prolapse into the atrium during systole; rupture leads to acute, severe regurgitation and rapid decompensation.
In early congestive heart failure, the body tries to maintain blood pressure.
a) Which branch of the autonomic nervous system activates first?
b) List two cardiovascular effects of this activation that help maintain circulation initially.
Answer:
a) The sympathetic nervous system.
b)
-Tachycardia (↑ heart rate), and
Peripheral vasoconstriction (↑ systemic vascular resistance), which helps maintain blood pressure and cardiac output short term.
You’re reviewing the coagulation cascade.
a) ______ leads to formation of what key structural protein that stabilizes the platelet plug?
b) Which clotting factor is specifically responsible for cross-linking this protein to form a firm, stable clot?
Secondary hemostasis
a) Fibrin.
b) Factor XIII (fibrin-stabilizing factor).
If an animal hyperventilates (breathes faster and deeper) without changing its metabolism, what happens to:
a) PaCO₂
b) blood pH?
Answer:
a) PaCO₂ goes down.
b) Blood pH goes up (respiratory alkalosis).
You’re describing the branching order of the lower airways.
a) Starting from the trachea, what is the general order of the bronchial tree down to the smallest functional units?
b) Which structure is the primary site of gas exchange?
a) Trachea → main (primary) bronchi → lobar (secondary) bronchi → segmental (tertiary) bronchi → bronchioles → terminal bronchioles → respiratory bronchioles → alveolar ducts → alveolar sacs.
b) Alveoli are the main site of gas exchange.
You’re tracing the coronary arteries on a diagram.
a) The circumflex branch is a branch of which coronary artery?
b) Damage to this branch most directly compromises perfusion to what part of the heart?
Answer:
a) The left coronary artery (LCA).
b) Mainly the left atrium and the lateral/posterior wall of the left ventricle.
You’re treating a dog with degenerative mitral valve disease and regurgitation.
a) Name the drug that acts as an “inodilator” commonly used in this scenario.
b) Briefly describe its two main actions on the heart and vasculature.
a) Pimobendan.
b)
Positive inotrope – increases cardiac contractility, and
Vasodilator – decreases preload and afterload, improving forward stroke volume.
You’re studying pacemaker cells in the SA node.
a) Which phase of the action potential is associated with the “funny” current (If) in these cells?
b) What is the functional effect of this “funny” current on heart rate?
Phase 4
b) The funny current causes slow, spontaneous depolarization, allowing the SA node to reach threshold and set the heart rate; increasing this current increases heart rate.
Alveolar PO₂ is influenced by alveolar ventilation.
a) If alveolar ventilation decreases (hypoventilation), what happens to PaCO₂ and PaO₂?
b) Which parameter can the clinician directly adjust in an anesthetized patient to correct this?
a) PaCO₂ increases (hypercapnia) and PaO₂ decreases (hypoxemia).
b) The clinician can increase alveolar ventilation (e.g., ↑ tidal volume or respiratory rate on the anesthetic machine).
After autopsy, a dog showed poor lung compliance and collapsed alveoli.
What typically helps assist in a healthy animal to prevent this from occurring. (Think of a specific helping factor in the body and explain its mechanism)
Surfactant.
b) Without enough surfactant, surface tension is high, especially in small alveoli, making them more likely to collapse (atelectasis) and reducing lung compliance.
You’re reviewing thoracic anatomy in a dog and a horse.
a) Where is the cardiac notch typically found in the dog (side and general rib space region)?
b) Clinically, why does knowing the location of the cardiac notch matter for procedures like pericardiocentesis or auscultation?
a) On the right side, roughly in the 4th–5th intercostal space, where lung tissue is minimal.
b) It marks an area where the heart is in more direct contact with the thoracic wall, making it important for safe needle placement and for getting clear heart sounds with minimal lung interference.
A 9 year old dog CKCS with degenerative mitral valve disease is started on medication that blocks aldosterone receptors. Two weeks later, the owner reports the dog is drinking and urinating more than usual and it seems slightly more tired.
What medication was prescribed and what class of vasodilators does it belong?
spironolactone
aldosterone receptor antagonist
List the intrinsic, extrinsic and common pathways. describe which is the longest factor and which are vitamin K dependent.
Intrinsic pathway: XII → XI → IX (+VIII) → X, extrinsic pathway: III (tissue factor) + VII → X, and common pathway: X → V → II → I → XIII, with factor II (prothrombin) having the longest half-life.
The vitamin K–dependent factors are II, VII, IX, and X
You’re monitoring a hypoxic dog. Pulse oximetry reads an SpO₂ of 86%.
a) This saturation corresponds to what general severity of hypoxemia?
b) Why is this value considered an emergency in terms of the O₂–Hb dissociation curve and tissue oxygen delivery?
a) Severe hypoxemia.
b) At ~86% saturation, the patient is on the steep part of the O₂–Hb curve, so small drops in PaO₂ cause large decreases in saturation, greatly compromising tissue O₂ delivery and risking organ dysfunction or death.
A dog with laryngeal paralysis has a noisy, harsh breathing sound (stridor).
a) Is the noise usually louder on inspiration or expiration?
b) Is this problem considered an upper airway (extrathoracic) or lower airway (intrathoracic) obstruction?
Answer:
a) It is usually louder on inspiration.
b) It is an upper airway, extrathoracic obstruction.