Lab Exercises
Abomasal Nematodes of Sheep and Cattle
Estimate the number of strongyle type eggs per gram of sheep feces using the McMaster Egg counting method.
Click here to link to the data form to submit your fecal examination results.
With the advent of multi-drug resistance in many of the GI nematodes of sheep
and goats (and in some areas cattle) a fecal egg count is becoming a necessity
in the management of ruminant herd health. Drug resistance can be defined by the
Fecal Egg Count Reduction Test (FECRT) . This is just 2 fecal egg counts, one done
before drug treatment and the other done post-treatment (the
time post-treatment varies with drug used). A
reduction of less than 85% indicates the worms are resistant to the drug used.
The following nematodes might be found in a sample of the abomasum's contents
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Haemonchus
largest: 2-3 cm
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Ostertagia
intermediate: ~1 cm
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Trichostrongylus
smallest: less than 7mm long
(penny = 19mm) |
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A. Haemonchus contortus
Common name of this worm is "Barber pole worm" because the white ovaries of the females wrap around the intestine, which, when full of
blood gives the appearance of a barber pole. The male worm will have an asymmetrical dorsal ray (ie: the
dorsal ray arises from one side of the mid-line). (See pg 19 of the text: Urquhart, et
al.), however, you are not responsible for identifying this feature on the males, it is
enough to know that the worm is a male and because of its size it probably is Haemonchus
contortus.
The number of worms in a sheep or goat can qualitatively be estimated by the
use of the FAMACHA eye chart (see DEMO) which measures the level of anemia in
the animal. The greater the level of anemia, the greater the number of H.
contortus.
Click here to link to the life cycle for Haemonchus contortus
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In this worm the vulva is protected by a flap of the cuticle. |
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The dorsal ray of
the bursa emerges from the side of the bursa rather than along the mid-line as in other
bursate worms. |
B. Ostertagia sp.
Of the 3 nematodes found in the abomasum of sheep, this species is intermediate in size
(about 1 cm long).
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C. Trichostrongylus axei
The smallest of the abomasal nematodes, less than 7mm long (hard to see with the naked
eye).
Small Intestine Nematodes of Sheep and Cattle
A. Other Trichostongylus sp.
B.Cooperia sp.
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A small worm ~4-6 cm, a.k.a. "watch spring" worm because it may be tightly coiled.
The cuticle of the anterior end is slightly swollen (cephalic vesicle) and striated. |
D. Nematodirus sp. A long worm (about 1 to 2 cm). The spicules of the male
extend past the bursa. The egg is twice as large as any other strongyle - type egg.
Stomach of
Cats and Swine
Ollulanus tricuspis This small
nematode (~1 mm) is ovoviviparous (gives birth to larva rather
then eggs, the eggs hatch in the uterus) and transmission is
via the vomit.
 
Adult Female (1 mm)
Tail of female (3 cusps)
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Hookworms
Ancylostoma sp.
Ancylostoma caninum (L3) vs. Stongyloides stercoralis (L3)
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Ancylostoma caninum (L3) |
Stongyloides stercoralis (L3) |
sheath |
present |
absent |
esophagus |
bulbed and runs ~ 25% the length of the worm |
straight and runs ~ 40- 50% the length
of the worm |
tail |
straight |
notched |
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Ancylostoma caninum
Anterior end of an adult worm showing the 3 pairs of ventral teeth. Note
that the mouth is bent to the side of the worm.
(Ancylo= bent, stoma = mouth; therefore: hookworm) |
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Bursa of an adult male A. caninum. |
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Adult A. caninum in a petri dish. |
Click here to link to the Ancylostoma caninum life cycle.
Ancylostoma braziliense below: anterior of adult worm (note the 2 pairs of teeth)
Other Hookworms
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Uncinaria stenocephala
Note the cutting plates instead of teeth. |
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Bunostomum sp.
Large hookworm found in sheep/cattle with cutting plates in the mouth capsule of the adult worm |
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