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.
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
 |
Haemonchus
largest: 2-3 cm
|
 |
Ostertagia
intermediate: ~1 cm
|
 |
Trichostrongylus
smallest: less than 7mm long
(penny = 19mm) |
Top of Page
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
 |
In this worm the vulva is protected by a flap of
the cuticle. |
 |
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).
Top of Page
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.
 |
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)
Top of
Page
Hookworms
Ancylostoma sp.
Ancylostoma caninum (L3) vs.
Stongyloides stercoralis (L3)
| |
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 |
 |
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) |
 |
Bursa of an adult male A. caninum. |
 |
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
 |
Uncinaria
stenocephala
Note the cutting plates instead of teeth. |
 |
Bunostomum
sp.
Large hookworm found in sheep/cattle with cutting
plates in the mouth capsule of the adult worm |
Top of the Page
Top of the Page | 
