Cardiovascular & Respiratory System

What is the most important principle when examining the heart at necropsy?

Observation comes before protocol and sampling — carefully orient and assess the heart before cutting.

What structure is used for orientation of the heart?

The right auricle is the key landmark for orientation

What chamber features must always be assessed?

• Size of the atria

• Wall thickness

• Chamber volume

Why is the septum important during examination?

The septum is your guide to distinguishing left vs right sides and assessing symmetry or hypertrophy

What is the correct directional flow to follow when examining chambers?

Atria → inflow → outflow

What learning tools are emphasized for mastering heart examination?

• Courselink videos

• Necropsies

Why is external orientation critical before cutting?

Incorrect orientation can lead to misidentification of chambers, vessels, or lesions

What are the two key external grooves used to orient the heart?

• Subsinuosal groove

• Paraconal groove

They correspond to interventricular septal orientation and help distinguish right vs left ventricular surfaces

Which groove on the heart is typically visible on the right side?

The subsinuosal groove

Which groove on the heart is typically visible on the left side?

The paraconal groove

What core steps should you mentally follow in an exam setting when identifying heart anatomy?

• Locate the right auricle

• Identify right vs left side

• Assess atria size

• Compare wall thickness and chamber volume

• Use septum as guide

• Follow atria → inflow → outflow

prevents random guessing and ensures systematic identification of lesions and chambers

What does a VSD cause physiologically?

Left-to-right shunt, increased pulmonary blood flow, volume overload

What are the two major endocardial diseases?

• Endocardiosis (degenerative)

• Endocarditis (infectious) → inflammation + thrombosis

What is endocardiosis (MMVD)?

Chronic degenerative disease of cardiac valves, especially mitral → Very common in dogs

• Shiny, smooth nodules → fibrous tissue over the valve

• Valve distortion

Valvular incompetence → volume overload

How do you tell if valvular disease is significant?

Look for secondary changes:

• Atrial dilation

• Ventricular hypertrophy

• Congestion or edema

Normal structures of the dog aortic valve

1. Nodule in centre

   of each cusp

2. Ventricular

   outflow: all muscle

   until annulus of

   valve cusp

• L atrium is larger → functionally significant, regurge of blood

• L ventricle is very big

• shiny nodules on valve

• jet lesion

• outside the heart → pulmonary congestion and edema, heart failure cells, effusion

Lesions of LEFT heart failure?

• Pulmonary edema & congestion

• Heart failure cells

• Pleural effusion (cats, both)

Lesions of RIGHT heart failure?

• Ascites

• Congested/enlarged liver

• Subcutaneous edema

• Pleural effusion

• Pulmonary Congestion

What findings indicate compensation (not failure)?

• Atrial dilation

• Eccentric or concentric hypertrophy

What is endocarditis?

Bacterial infection of valves with thrombosis and neutrophilic inflammation

Gross appearance

• Rough, dull, irregular vegetations

Sequelae

• Valvular insufficiency

• Septic emboli

• Heart failure

What is the lesion

Endocarditis in the dog → less severe

Causes of acute worsening in chronic heart failure?

• Myocardial ischemic necrosis

• Ruptured chordae tendineae

• Left atrial dilation, rupture, hemopericardium, tamponade

Ruptured vs. Cut chordae tendineae

What causes gritty endocardial lesions in dogs?

Barbiturate euthanasia artifact

Endocardial hemorrhages in horses indicate?

Often incidental, consider sepsis context.

Blood-filled cysts in neonatal calves?

Common and insignificant