Lecture 2 - What is Pathology?

Define etiology.

the "cause" of the disease

What are two types of etiologies? What is included in each category?

1. Intrinsic: primary (genetic mutations) or secondary (age, sex, breed, etc)

2. Extrinsic: Inanimate forces or animate agents

Define pathogenesis.

how the disease develops

Define lesions. What types of lesions can be found?

-Structural alterations in cells or tissues

-Macroscopic, microscopic, or ultrastructure

What is a pathognomonic lesion?

A lesion that is characteristic for a particular disease (rare)

Define clinical signs.

-Manifestation of disease from the physician’s perspective

-Objective and usually measurable

Define symptoms

-Manifestation of disease from the patient’s (or owner’s) perspective

-Vague and unmeasurable

Define diagnosis.

interpretation of the nature of the disease based on clinical signs and lesions

What are the three types of diagnoses?

1. Morphologic diagnosis

2. Etiologic diagnosis

3. Disease or condition

What are the characteristics of a morphologic diagnosis?

-Descriptive in nature

-Focuses on one lesion (or related lesions)

-Specific etiology not provided

What are the characteristics of an etiologic diagnosis?

-Less descriptive

-Does not always identify a specific lesion

-Focuses on etiology of the lesion

Define prognosis. What is it expressed in?

-Estimate of future outcome

-Expressed in terms of optimism (excellent, good, fair, guarded, poor)

Explain the difference b/w statistical and clinical significance.

Statistical significance is the probability that the results are due to chance while clinical significance is the difference between intervention and control groups

How can you differentiate between antemortem and postmortem lesions?

-with antemortem lesions, will most likely see changes in the tissue's appearance --> due to chronic injury/inflammation

-postmortem, most likely a normal tissue appearance

What are some common postmortem changes?

(1) lesions secondary to euth (barbiturate salts, splenomegaly)

(2) algor mortis (post-mortem cooling)

(3) rigor mortis (rigidity)

(4) liver mortis (blood pooling)

(5) staining (imbibition)- due to bile, hemoglobin, etc.

(6) gas distension/rupture