Introduction to Pathology

Pathology & Parasitology for Veterinary TechniciansLeland S. Shapiro

Thomson* Delmar Learning

Pathology is the scientific study of disease.

Pathos = suffering or diseaseLogos = the study of

This study is divided into 4 parts:

1. Etiology – the study of the cause of disease, which may be

genetic or acquired. Genetic etiologies arise from changes within

genes. Acquired etiologies refer to disease caused by outside

sources, such as bacterial or viral infections or metabolic or

nutritional disorders.

2. Pathogenesis – the study of mechanisms in the development of disease.

This describes the sequence of events - the – progression of changes from their inception – at the cell and tissue levels as a disease expresses itself.

3. lesions – the study of morphological alterations in tissues that occur with disease.

Lesions give rise to functional disturbances – serve to distinguish one disease from another and occasionally may be diagnostic of an etiologic agent.

The alteration of tissue is studied by gross examination and by microscopic examination.

Changes are described according to size, color, shape, consistency, and weight.

The surgical removal of lesions within organs and tissues, primarily for the purpose of examination = biopsy

4. diagnosis – the study of the functional consequences of these lesions, which give rise to physical signs or symptoms of disease

necropsy – the examination of animal’s body after death, can help lead to diagnosis.

Differential Diagnoses – a list of possible diseases possessing the same or similar symptoms.

Ischemia – deficiency of blood in an area due to obstruction or constriction of blood vessel.

In the twentieth century, techniques and concepts of autopsy pathology became clinically practical.

Tissue samples could be removed from patients and interpreted to determine a diagnosis, a course of therapy, and a prognosis (or forecast of the outcome of a disease).

Pathologists also began to study the chemicals of the body, which led to the development of clinical and experimental pathology.

Virology was established in 1898, when Friedrich Loeffler and Paul Frosch demonstrated that foot-and-mouth disease in cattle was caused by a virus small enough to pass through a fine-pored filter.

Causes of Cell or Tissue Lesions

Classes of Cell or Tissue Lesions

1. Heredity 1. Disruptive

2. Congenital 2. Degenerative

3. Toxic 3. Blood vessel/circulataory defects

4. Infections 4. Inflammatory

5. Trauma 5. Growth and differentiation defects

6. Degenerative 6. Developmental

7. Immunologic

8. Neoplastic

9. Nutritional

10.Metabolic

11.Latrogenic

12.Hypoxia (lack of oxygen)

Anoxia (absence of oxygen in the blood or tissues)

Ischemia