Download Introduction to Pathology

Pathology & Parasitology for Veterinary Technicians
Leland S. Shapiro
Thomson* Delmar Learning
Pathology is the scientific study of disease.
Pathos = suffering or disease
Logos = 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