Diagnosis of Internal Parasites of Ruminants

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Diagnosis of Internal Parasites of Ruminants
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Signs of Heavy Parasitism Infection with
ruminant gastro-intestinal parasites may cause
the following clinical signs to some degree,
depending on the severity of infection Diarrhea,
dehydration, reduced weight gain and emaciation
(1) bottle jaw (hypoproteinemia), rough hair root
(2) and anemia (3). Liver and lung parasites may
cause similar or additive effects involving liver
and lung pathology respectively. Cattle and sheep
have a striking similarity in the complement of
parasites that affect them and usually only
different species of identical genera are
involved. In general, sheep are somewhat less
resistant to the effects of parasitism than
cattle and build heavier infection levels more
easily. Only genera are discussed in this
program.
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Abomasal Parasites (Ostertagia, Haemonchus,
Trichostrongylus axel)
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Ostertagia egg Ostertagia has an egg that is
morphologically typical of Trichostrongylid eggs.
With only minor or statistical variations in size
and shape, similar appearing eggs are also passed
by Haemonchus, Trichostrongylus,
CooperiaandOesophagostomwn. For reporting
purposes, these eggs will be reported as
trichostrongyle-type eggs by Diagnostic Services
at I.SU. These are the most common type of eggs
encountered in bovine fecal specimens and are
reported as eggs per gram (EPG) after a
quantitative sugar fecal flotation procedure
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Ostertagia nodular lesions in abomasum.
Ostertagia is probably the most important G-I
parasite of cattle and sheep in Louisiana and
causes small nodular lesions due to a
.histotropic phase. of development in the
abomasal mucosa.
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Histotropic phase Each nodule contains a
developing or an arrested. larvae which will
eventually emerge to the lumen and the adult
phase. In sufficient numbers these nodules and
emergence of larvae are quite pathogenic, leading
to disturbed mucosal secretory function, a rise
in abomasal pH and loss of fluids and protein to
the lumen. (fype II or Type I Ostertagiasis).
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Adult Ostertagia compared to a paper clip Adult
worms are small and are visible to the naked eye
only with difficulty when recovered at necropsy.
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Haemonchus contortus egg Note similar
appearance to Ostertagia eggs. Haemonchus is a
larger worm than Ostertagia (female 2.5cm male
1cm VS female 1.0cm male 0.5cm.).
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Trichostrongylus eggs Note typical
trichostrongylid egg. Trichostrongylus often has
a slightlyeccentric egg shape as shown here.
In sufficient numbers, this parasite may cause
catarrhal inflammation and diarrhea (called the
.bankrupt worm.). Trichostrongylus is a very
small worm which is barely visible to the naked
eye. (0.3- 0.5 cm).  
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Intestinal Parasites (Trichostrongylus,
Cooperia, Nematodirus, Bunostomwn,
Oesophagostomwn, Chabertia, Trichuris ,
Strongyloides , Moniezia
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Cooperia ova A typical trichostrongylid egg ,
note the longer shape with parallel sides as
compared to other species. Intestinal
Trichostrongylus spp. and Chabertia shed similar
eggs.
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Nematodirus in situ intestines This long, thin
worm (1-2 cm) is mainly found where cold climates
prevail (it requires prolonged cold for
development). Cooperia and Trichostrongylus are
the most common intestinal nematodes in Southern
states.
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Nematodirus egg Nematodirus has a very large
unique egg which is not confusible with other
trichostrongyles
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Bunostomum in situ A hookworm that frequently
infects cattle in Louisiana and warm climates
less frequently elsewhere). It is a voracious
blood sucker and is found in the small intestine.
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Bunostomum sp. Bunostomum eggs are distinctive
and are somewhat larger (80 x 50 u) and darker
than trichostronylid eggs and should be reported
as a separate item
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Strongyloides papillosis egg This species of
cattle and sheep affects mainly young animals. It
is called the intestinal threadworm(found in
small intestine) and distinctive embryonated eggs
are passed. Transmammary infection can occur .
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Chabertia This species (1-2cm) has a very large
buccal capsule, skin penetration and inhabits the
colon and is of relatively little importance.
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Chabertia eggs Typical trichostrongylid egg
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Oesophagostomum adults in situ / colon Adults
are large, stout worms (1-2cm) and can be a major
pathogen in high numbers. The egg is a typical
trichostrongylid type .
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Oesophagostomum lesions The main damage of
this species is by the larvae in the gut wall
which produces small abcesses, mucosal sloughing.
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Trichuris egg Whipworms occur in the caecum of
cattle and sheep and of little importance.
Capillaria eggs from adults in small intestine
(also of little importance) are also occasionally
seen on fecal examinations
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Eimeria sp. Coccidia can cause bloody diarrhea
in cattle or sheep particularly in feedlot or
other close confinement situations, such as dairy
calf barns. Although many species of Eimeria
affect cattle and sheep, only a few are actually
of any significance as pathogenic. In cattle E.
bovis, E. zurni are reported as mixed coccidia
including E. bovis, E. arlongi, etc. Impression
smears may be indicated on necropsy cases.
Pathogenic species are identified by shape and
size of oocyst.
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Bovine rectum Bloody diarrhea, lesions
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Moniezia egg This tapeworm of cattle and sheep
is non-pathogenic. Note typical shape.
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Mixed Parasite Infection -Flotation. Note
relative sizes of trichostrongyle-type eggs,
Nematodirus , Moniezia and mixed Eimeria species.

Moniezia
Eimeria spp
Strongyloides
trichostrongyle-type
Nematodirus
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Comment of Quantitative egg counts. Quantitative
egg counts will be used as a rough indicator of
infection level. There are many variables
(parasite species, fluid stool, .spring rise.,
.self-cure., immunity, age, etc.) that some say
destroys any confidence put in quantitative
counts in ruminants. With these limitations in
mind, however, eggs per gram reporting can be a
supporting factor in diagnosis parasitism.
Several daily counts or a sample of at least 10
head from a herd tends to cancel variation. A
mail-in fecal examination kit program is
available to practitioners/county agents to
monitor efficacy of parasite control programs
(submit and mid winter example for nematodes
fall sample for flukes) herd history and
anthelmintics used are considered in telephone
advisories.
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Necropsy Diagnosis At necropsy, parasites
present can be identified to genera fairly
easily by certain key traits. If a case is
important enough to warrant the time necessary ,
a total worm count is the most reliable way to
assess herd parasitism
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Ostertagia -small ( lt 1 cm) .Abomasal worm with
cervical papillae.
Cervical papillae
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Haemonchus -larger (1-3 cm) worms, barber pole
appearance, cervical papillae present.
Cervical papillae
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Cooperia -alae at head, railroad track
cuticular striations.
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Trichostrongylus cervical notch.
Cervical notch
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Nematodirus male with very long, slender
spicules. Other species with stout spicules.
Females have spine at posterior end
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Eunostomum -Note large buccal cavity with cutting
plates.
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Oesophagostomum -Note cervical alae, carona
radiata large robust size.
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Fasciola egg Large animal flukes eggs do not
float and sedimentation procedures must be used.
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Fasciola in situ/ bile ducts Chronic wasting,
anemia results from heavy infections.
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Paramphistome. Rumen flukes note conical
morphology .
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Paramphistome egg Not distinguishable from
Fasciola in, size or appearance.
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Fascioloides magna Common in Louisiana or
swampy ranges shared with deer. Fluke host is
normally deer in cattle they wall off so no eggs
escape to feces (dead end host). Characteristic
very black pigment is often present.
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Fascioloides magna adult. Note large robust
shape with no -shoulders
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Dicrocoelium Small bile duct fluke which is
endemic in New York. Intermediate host is black
ant .
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Dicrocoelium egg Very small embryonated eggs
are passed.
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Thysanosoma in bile ducts of sheep This
fringed tapeworm occurs in high mountains
(gt6000 ft), in Western U.S. serving as a cause of
condemned livers. Fringe on each segment of
Thysanosoma Characteristic eggs are passed
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Fringe on each segment of Thysanosoma
Characteristic eggs are passed
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Dictyocaulus in situ in bronchi
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Dictyocaulus first stage larva Straight-tailed
Ll stage is passed in stool. They will float
(ZnSO4 spg 1.18 is the best flotation solution
to use), but crenate if stand for long in
solution. Baermannization can be done.
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Muellaris / Protostrongylus These lungworms
occur in goats and sheep, producing blister1ike,
granulomatous lesions beneath the serosal
surface. Land snail is intermediate host
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Muellerius larvae. Notch-tail larvae are
produced and can be recovered by flotation (
ZnSO4 spg 1.18 works best) or Baermann apparatus.
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The End