Biology/Life
Sciences
Standards
•(BLS) 10.a.
Agriculture
Standards
•(AG) C 9.1, C 9.2, C 9.4, C 13.3, D 6.1, D 6.3, and D 6.4.
•(Foundation) 1.2 Science, Specific Applications of Investigation and Experimentation: (1.a) and (1.d).
Name___________________
Date____________________
External Parasites
Purpose
There are two types of mites that live on animals. Demodectic mites (Deomodex spp.) are normal skin
inhabitants of animals when in small numbers. However, demodectic mites can cause demodectic
mange (demodicosis) when in large numbers. The second type, and the most damaging, are the
sarcoptic mites (Sarcoptes spp. And Notoedres spp.). These mites burrow into the layers of skin causing
a skin disease called scabies or scaroptic mange.
In all animals, demodectic mange or scabies causes intense itching in which the animal will scratch, chew
and rub constantly. Unlike demodectic mites, sarcoptic mites are highly contagious even to humans. The
purpose of this lab is to evaluate an animal with potential infection, and use the microscope to
investigate. i
Procedure:
Materials
1. Scalpel
2. Light lubricating oil
3. Microscope slides and cover slips
4. Canvas sheet
5. Cotton swab
6. Black paper
7. Dissecting needle
8. Animal with infection
Sequence of Steps
1. Place a drop of oil on a microscope slide.
2. With a clean scalpel, dip the scalpel blade into the drop of oil on the slide.
3. At the edge of the suspected area of infection, pick up a fold of the animal’s skin, pinching it
between the index finger and thumb.
4. Scrape the top of the fold several times in the same direction using the oil scalpel blade.
5. The scraping will stick to the blade.
6. Stop scraping when a small amount of blood is detected.
7. Place the tip of the scalpel blade containing the sample into the oil on the slide and with a
circular motion transferring the sample to the slide.
8. Apply the cover slip gently without pressing down too hard.
9. Additional oil can be added to the edge of the cover slip so the entire area under the cover slip is
filled.
10. Examine the entire area under the cover slip.
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LAB E-10
11. Low magnification of 100 power should be sufficient to detect the mites.
12. The procedure to detect ear mites in dogs, cats, foxes and rabbits requires the animal to be
restrained in a canvas sheet.
13. A cotton swab is placed into the external auditory canal and gently rotated to obtain the mite
sample.
14. The swab is placed on a small piece of black paper which can be examined with a hand lens to
see the mites.
15. Individual ear mites are transferred from the cotton swab on the tip of a dissecting needle to a
drop of oil on a microscope slide.
16. Place a cover slip on top of the oil.
Observations
1. Describe your observations, using complete sentences to describe what you found.
2. Based on your observations, what recommendations would you make for the care of this animal?
3. Describe the role of the skin in providing defenses against infection.
4. How do housing, sanitation, and nutrition influence animal health and behavior?
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LAB E-10
i
Dickson, Christine (2008).External Parasites. The Inside Story: How Agriculture Uses the Microscope.
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LAB E-10