Pathology Study of functional and morphological alterations that

Cause of Disease • Etiological agent – specific cause 1. Inanimate 1. Without life

Cause of Disease • Non-etiological agent – Contributing cause 1. Extrinsic (originate from outside

Pathological change • Used to aid in recognition and identification of disease • Circulatory

Pathological change • Circulatory disturbances (cont. ) – Hyperemia: – Telangiectasis: bulging of a

Pathological change • Cellular degeneration: process in which cells or tissues deteriorate – Results

Pathological change • Cellular degeneration: (types) – Cloudy swelling: – Fatty degeneration: results from

Pathological change • Developmental and growth disturbances: – Atrophy: – Hypertrophy: Increase in size

Pathological change • Inflammation: (acute or chronic) Helps to minimize effect of irritant or

Pathological change • Inflammation: (cont. ) – Serous: exudates of clear fluid from the

Pathological change • Inflammation: (cont. ) – Catarrhal: excessive production of mucus on the

Disease recognition and diagnosis • Clinical signs (what can be determined) – Behavioral signs

Disease recognition and diagnosis • Clinical signs – External signs • Generally not distinctive

Disease recognition and diagnosis • Gross internal lesions – Necropsy (general characteristics: important to

Disease recognition and diagnosis • Disease diagnosis – Examine small number of animals •

Disease recognition and diagnosis • General procedures: – Parasitic diseases: • Perform external/internal exam

Disease recognition and diagnosis • General procedures: – Viral diseases • Require special techniques

Disease recognition and diagnosis • General procedures: – Bacterial diseases: • Isolation of pathogen

Disease Management (specific considerations) • Fish handling/stocking: – “Fish are not potatoes” • Transporting,

Disease Management • Feed management: – – – • • Water flow management: Aeration

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Pathology • Study of functional and morphological alterations that develop in an organism as a result of injurious agents, nutritional deficiencies, or inherited characteristics. • Basic Terms: – – – – – Etiology: Etiological agent: Pathogenesis: Pathogenicity: Virulence: Lesion: Clinical Signs: Histology: Histopathology:

Cause of Disease • Etiological agent – specific cause 1. Inanimate 1. Without life (endogenous/exogenous) 1. 2. 3. 2. Animate 1. 2.

Cause of Disease • Non-etiological agent – Contributing cause 1. Extrinsic (originate from outside body) 1. 2. Intrinsic (within body) 1. 2. 3.

Pathological change • Used to aid in recognition and identification of disease • Circulatory disturbances: (lesions that reflect injury to the vascular system) – Anemia: – Hemorrhage: – Edema: • Ascites: • Exopthalmia: fluid behind or in the eye

Pathological change • Circulatory disturbances (cont. ) – Hyperemia: – Telangiectasis: bulging of a blood vessel in the gills (similar to an aneurysm in higher vertebrates) – Embolism:

Pathological change • Cellular degeneration: process in which cells or tissues deteriorate – Results from: • • • Mechanical, thermal, electrical injury •

Pathological change • Cellular degeneration: (types) – Cloudy swelling: – Fatty degeneration: results from accumulation of lipids – Necrosis:

Pathological change • Developmental and growth disturbances: – Atrophy: – Hypertrophy: Increase in size of body part or organ due to increase in size of cells – Hyperplasia: increase in size of body part or organ due to increase in number of cells

Pathological change • Inflammation: (acute or chronic) Helps to minimize effect of irritant or pathogen on tissue. – Classic signs (mammals): 1. Redness (hyperemia) 2. 3. 4. Pain 5.

Pathological change • Inflammation: (cont. ) – Serous: exudates of clear fluid from the vascular system (ex: blister) – Fibrinous: escape of large amounts of fibrin from blood vessels and form a clear clot when exposed to air – Purulent:

Pathological change • Inflammation: (cont. ) – Catarrhal: excessive production of mucus on the epithelial surfaces of the skin, gills, and digestive tract – Hemorrhagic: – Granulomatous:

Disease recognition and diagnosis • Clinical signs (what can be determined) – Behavioral signs • • •

Disease recognition and diagnosis • Clinical signs – External signs • Generally not distinctive to particular disease • Some characterized by specific lesions • Common signs include: – – – Deformities

Disease recognition and diagnosis • Gross internal lesions – Necropsy (general characteristics: important to determine if bacterial, parasitic, or viral) • Clear, straw-colored fluid in abdominal cavity • • Small uniform cysts in internal organs

Disease recognition and diagnosis • Disease diagnosis – Examine small number of animals • • – Perform complete laboratory examination • External/internal exam (parasites) •

Disease recognition and diagnosis • General procedures: – Parasitic diseases: • Perform external/internal exam before disinfectant applied • Anesthetic may affect external parasites • • Internal parasites identified by observing various organs • Histopathology may be valuable to identify tissue dwelling parasites

Disease recognition and diagnosis • General procedures: – Viral diseases • Require special techniques • • Electron microscopy • Serological and molecular procedures • •

Disease recognition and diagnosis • General procedures: – Bacterial diseases: • Isolation of pathogen on/in media • Characterize/identify biochemically, serologically, or by molecular methods • Most grow on general media (BHI, TSA, TYE, etc. ) • FAT, ELISA, etc.

Disease Management (specific considerations) • Fish handling/stocking: – “Fish are not potatoes” • Transporting, spawning and stocking • Treating during transport • Acclimating to temperature changes • Crowding/density

Disease Management • Feed management: – – – • • Water flow management: Aeration management: Waste management: Disease treatment/vaccination practices