Using a Microscope

Using a microscope, like many other things, takes practice.

  1. Put the microscope slide on the stage.
  2. Move the dials that move side to side and up and down until the sample is directly over the light source.
  3. Adjust the eye pieces (codicils) to your comfort. First, focus on the lowest magnification. To do this, look through the eye pieces and adjust the course focus until the image appears (image may be blurry). Use the fine focus for further adjustments until image is seen clearly.
  4. Assess the sample by moving across, down, and in rows to examine the entire slide.

Note:

It is prohibited by the Kentucky Board of Veterinary Examiners to diagnose disease in animals if you are not a licensed veterinarian. While doing fecal tests on your own animals is allowed and encouraged to detect and treat intestinal parasites in your herd, you CANNOT perform this service for other farmers if you are not a licensed veterinarian. http://www.cfsph.iastate.edu/FastFacts/pdfs/contagious_ecthyma_F.pdf

Identification charts are helpful to keep as a reference. You may get one from your local veterinarian.

Health Impact and Characteristics of Internal Parasites

ParasiteApproximate Length (μ m)Characteristics
Ostertagia (brown stomach worm)60-70Medium-sized, standard strongyle egg; barrel-shaped sidewalls; large number of blastomeres nearly fills egg
■ Supresses appetite
■ Weight loss, poor body condition
Haemonchus (barberpole worm)85Larger and rounder than Ostertagia egg; blastomeres more easily seen than in Ostertagia
■ Anemia
■ Death common in sheep and goats
Trichostrongylus (bankrupt worm)85Often shaped like a kidney bean; one side is more rounded than the other; there is usually a lot of clear space within the egg
■ Watery diarrhea
■ Slowed growth
Cooperia (small intestinal worm)75-85Medium-sized egg with parallel sides and numerous blastomeres that are hard to distinguish
■ Diarrhea
■ Slowed growth
Nematodirus (threadneck worm)200Large egg; looks like an American football with basketballs inside; two to eight large blastomeres are surrounded by a fluid-filled cavity
■ Diarrhea
■ Slowed growth
■ Emaciation and death in sheep, young cattle
Oesophagostomum (nodular worm)95Medium-sized to large egg; about one and a half times the size of the Ostertagia egg; 16 to 32 blastomeres; are easier to see than those of Haemonchus
■ Diarrhea
■ Slowed growth
Bunostomum (hookworm)100Medium-sized to large egg; four to eight blastomeres; sometimes the walls are thick and rectangular
■ Anemia
■ Weight loss
Strongyloides (threadworm)40-65Small egg with a thin shell containing an L1 larva that can be seen under low power
■ Diarrhea in young
■ Fatal infections reported in young raised on sawdust
Trichuris (whipworm)75Egg is shaped like an American football and has two protruding polar caps; the shell is double and thick
■ Reduced appetite
■ Slowed growth
Coccidia16-47Coccidia appear small in size, pink in color; size and shapes vary depending on species
■ Bloody diarrhea in young cattle
■ Reduced weight gains in sheep, goats, cattle
■ Death can occur in calves, lambs, kids and adult goats
Moniezia (tapeworm)80x80Quadrangular; somewhat irregular; contains a circular or pear-shaped apparatus at one end
■ Blocks small intestine in lambs
■ Loss of nutrients
Dictyocaulus (lungworm)450Rectal sample of feces needed for positive identification; L1 larva found in feces; flattened head and tail end in blunt point
■ Cough
■ Reduced appetite and milk production

Ostertagia (brown stomach worm) Cooperia (small intestinal worm) Moniezia (tapeworm - sheep) Moniezia (tapeworm - cattle) Bunostomum (hookworm)

Trichuris (whipworm) Strongyloides (threadworm) Coccidia (a protozoan that causes coccidiosis) Dictyocaulus (lungworm) Mite Egg - 1/4 actual size (contaminant - often mistaken for worm eggs)

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Modified Wisconsin Sugar Fecal Worm Egg Flotation Method

  1. Fecal samples can be stored for long periods if refrigerated (not frozen).
  2. Sugar solution is prepared by adding 1 lb. of sugar into 12 fluid oz. (355 ml) of hot water: stir until all sugar is dissolved.
  3. Slides can usually be placed in the refrigerator for several days prior to reading.
  4. Identify parasites present: + (1-10 eggs/sample) ++ (11-50 eggs/sample) +++ (over 50 eggs/sample)
  5. # of eggs found x 150 = # of eggs per pound feces
  6. Materials needed:
  7. Sugar solution plus dispensing
  8. Taper-bottom test tubes
  9. Test tube rack
  10. Tongue depressors
  11. Taper-bottom test tubes
  12. Test tube rack
  13. Standard microscope slides
  14. Centrifuge
  15. Microscope

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