Diagnostic Laboratory Procedures

Diagnostic Diagnostic Laboratory Laboratory ProceduresProcedures

Microscope UseMicroscope Use• Objective lenses 4x, 10x, and Objective lenses 4x, 10x, and

40x40x• Oil-immersion is used Oil-immersion is used

occasionallyoccasionally• A mechanical stage is necessary A mechanical stage is necessary

to view slides thoroughlyto view slides thoroughly

Microscope UseMicroscope Use

• Viewing area = fieldViewing area = field

Microscope UseMicroscope Use• To scan a slide use 4x to To scan a slide use 4x to

focus, then move to 10xfocus, then move to 10x

• Scan back and forth Scan back and forth overlapping each fieldoverlapping each field

Microscope UseMicroscope Use

Scanning patternScanning pattern

Microscope UseMicroscope Use• Debris can be closely Debris can be closely

examined under high examined under high powerpower

Sample Collection• The animal owner will

most often collect the stool sample.

Sample Collection• The sample should be

fresh since some parasite eggs become unrecognizable as the feces ages.

Sample Collection• If a fresh sample cannot

be obtained, one can be refrigerated, but for no longer than 24 hours.

Methods1. Gross exam

- used to observe outward characteristics of the sample.

Methods1. Gross exam

- Several abnormalities can be seen with the naked eye.

Methods1. Gross exam

- observe and record• color and consistency• blood and mucus• age of sample• presence of adult parasites

Methods

2. Direct smear

- the fastest and simplest method of diagnosing parasitism.

Methods2. Direct smear

- A small amount of feces is mixed with water and applied directly to a slide.

Methods2. Direct smear

- The main disadvantage of this technique is that a

small sample may not contain any parasite eggs.

Methods2. Direct smear

- This method also leaves debris on the slide.

Methods3. Floatation

- the most commonly used procedure for diagnosing parasitism.

Methods3. Floatation

- techniques using this method:

- simple floatation

- use of a centrifuge

- Fecalyzer

Methods3. Floatation

Fecalyzer- uses a solution (zinc sulfate or sodium nitrate) that has a specific gravity greater than the specific gravity of most parasite eggs

Methods4. Sedimentation

- is commonly used for eggs that have a high specific gravity

Methods4. Sedimentation - The high specific gravity

of these eggs makes it difficult to use floatation techniques without

distorting them.

Methods4. Sedimentation

- Sedimentation allows eggs to sink to the bottom.

Debris

• may be easily confused with parasite eggs.

Common Debris:• hair• plant material• air bubbles

•fat

•epithelial cells

•pollen grains