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Principles of Aquaculture Diagnostics

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Title: Principles of Aquaculture Diagnostics


1
Principles of Aquaculture Diagnostics
  • Dr. Craig Kasper
  • FAS 2253
  • Fall 2006

2
Introduction
  • Readings from Chapters 1-5 of Noga (1996)
  • What are diagnostic tests?
  • A series of tests designed to determine the
    health status of a healthy population of animals
    vs. that of a population of animals deemed
    unhealthy. (Healthy vs. sick)

3
Introduction
  • 2. Why should they be performed?
  • Often involves establishing a background or
    baseline information concerning the health of a
    population of animals, i.e. parasite load,
    nutritional status, bacterial exposure.
  • Anything that is considered abnormal is also
    known as a lesion.

4
Introduction
  • 3. How should these tests be performed?
  • Hopefully, under strict guidelines using quality
    control and S.O.Ps with a list of written
    procedures! But doesnt always happen.
  • Look for American Association of Veterinary
    Laboratory Diagnosticians accreditation (ADVLD).

5
Introduction
  • 4. Who is qualified to perform these tests?
  • a. Two issues should be addressed here, esp. if
    you are the one performing the tests.
  • i. Moral Can I do it? (I might actually have
    the skills.)
  • ii. Legal Am I licensed to do it? (Can I
    testify in court? Am I liable if I am wrong?
    Rem drugs, pharmacy, licenses, etc.
  • What would I need? DVM, Ph. D., affiliation with
    university or organization (lab), ACVP,
    Diplomate, AFS pay dues for being a fish health
    inspector!

6
Introduction
  • 5. What should be included in the diagnostic
    evaluation?
  • a. Animals
  • b. Facilities
  • c. Environment, i.e. water quality, feed
  • d. Questions for the producer/owner!
  • May be the most important piece of information.

7
Introduction
  • What is the final outcome of the diagnostic?
    What should the lab tell you?
  • Your fish have a clear case of acute multifocal
    necrotizing supperative hepatisis!
  • WHAT??? Translation PLEASE!!

8
Introduction
  • Acute multifocal necrotizing supperative
    hepatitis
  • Time location dead neutraphils
    inflammation
  • cells of the liver
  • A rapid onset of dead white blood cells
    throughout an inflammed liver, put simply your
    fish have bacterial hepatitis!

Why didnt you just say so?
9
Introduction
  • 6. What is the final outcome of the diagnostics?
  • a. Morphological Diagnosis (only?)
  • b. Recommendations re husbandry?
  • c. Treatment recommendations?
  • d. Changes in facilities, environment?
  • e. LABS WONT PERFORM TESTS TO DETERMINE IF FISH
    ARE SAFE FOR HUMAN CONSUMPTION.

10
Introduction
  • The clinical evaluation
  • a. History
  • b. Physical Examination
  • c. Clinical Signs
  • d. Gross lesions
  • e. Cytologic evaluation
  • f. Biopsy
  • g. Necropsy
  • h. Ancillary testing
  • bacteriology
  • virology
  • Toxicology (water and animal samples)
  • Clinical pathology (serum chemistries,
    hematology)j

11
Introduction
  • Sample sizes and inferences about a population
    based on samples.
  • Must have sufficient number or diagnosis is
    meaningless.
  • Over-interpretation
  • Under-interpretation

12
Statistics Sampling Size
Lot size Number of fish to sample
50 100 35 45
250 500 50 55
gt2000 60
Based on assumed 5 prevalence level in the
population.
13
Symptoms vs. Signs
  • Symptoms Description of how an individual feels
    to a proessional health care specialist. Why
    doesnt this work for aquatic critters?
  • Clinical signs Observation of behavior of
    non-healthy animals.

14
Common Clinical Signs
  • Anorexia
  • Flashing
  • Piping
  • Lethargy
  • Erratic Swimming Patterns
  • Isolation
  • Loss of Fright Response

15
Lesions vs. Pus, Crud or Goop?
  • A lesion simply stated isany abnormal
    (unhealthy) tissue.
  • Lesions may contain purulent exudate, hemorrhage,
    necrotic muscle, etc.

16
Examples of Lesions
  • Ascites
  • Exophthalmia
  • Hemorrhage and/or congestion
  • Cutaneous erosions and ulcerations
  • Gill necrosis
  • Abscesses
  • Granulomas

17
DO CLINICAL SIGNS LESIONS ALLOW YOU TO MAKE A
DIAGNOSIS?
18
NO!Clinical signs and lesions suggest to you
the possible disease processes. The diagnosis
can only be made by isolating or demonstrating
the presence of the pathogenic organism with a
concurrent disease process.
19
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