Internal Parasites of Livestock
Internal Parasites of Livestock

Internal Parasites: live within the internal
organs of livestock
◦ They are not visible
◦ Effects on the host may be visible

Divided into three groups
◦ Roundworms
◦ Tapeworms
◦ Flukes
Roundworms
Most important from economic
standpoint
 Many different types
 Affect almost every type of livestock

Stomach Worms
(Roundworm)

Host: Every species of livestock

Life Cycle:
◦ Adults live in stomach wall.
◦ Eggs pass from host and hatch into larvae
◦ Larvae are eaten by animal and travel to
stomach where they mature.
Stomach Worms
(Roundworm)

Damage:
◦ Penetrate stomach
lining
◦ Reduce digestion of
nutrients
◦ Young undernourished
animals are hit the
hardest

Symptoms
◦ Anemia- paleness of
gums and white of
eyes
◦ Dull hair coat
◦ Scours
◦ Severe infestation can
cause weight loss and
death
Strongyles
(Roundworm)

Host: All species of
livestock
◦ Cattle & horse can
build up immunity by
ages 4 or 5

Life Cycle:
◦ Adult is attached to
lining of intestines
◦ Eggs pass from host
◦ Larvae attach to grass
and are eaten by
animal
◦ Pass through stomach
and attach to intestinal
wall
Strongyles
(Roundworm)

Damage:
◦ Most detrimental
◦ Anemia
◦ Scar tissue reduces
digestion of nutrients
◦ Major cause of Colic
in horses
◦ Poor feed conversion

Symptoms
◦
◦
◦
◦
◦
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Anemia
Weight Loss
Scouring
Loss of appetite
Prostration
Rough hair coat
Ascarids
(Roundworm)

Largest of round worms
◦ Can reach 8 to 15 inches in length
Mainly affects younger animals
 Host: primarily cattle, sheep, hogs, and
horses

Ascarids
(Roundworm)

Life Cycle:
◦
◦
◦
◦
◦
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Eggs passed in feces contaminate pastures
Animals ingest
Larvae burrow into wall of intestine
Migrate to liver, heart, and lungs
Animal coughs up eggs and are swallowed
Reach intestines a 2nd time and develop into
adult stage
Ascarids
(Roundworms)

Damage:
◦
◦
◦
◦
Develop pneumonia
Weight loss
Lung damage
Colic in horses

Symptoms
◦ Weight loss
◦ Dull hair coat
◦ Colic
Pinworms
(Roundworms)

Small and found in colon or rectum of
horses

Host: mainly horses, but can be found in
other livestock species.
Pinworms
(Roundworms)

Life cycle:
◦ Adult females lay eggs around the anus of
horse
◦ Eggs drop off and contaminate pastures,
stables, watering and feeding area
◦ Eggs are ingested by animal
◦ Pass to colon and rectum and mature
Pinworms
(Roundworms)

Damage:
◦ Minor damage is
caused
◦ Cause irritation
around the tail

Symptoms:
◦ Tail rubbing
◦ White scales deposits
are visible around anus
Habronema
(Roundworm)
Affects host in two stages
 Host: Horse is major host

◦ House fly is intermediate host
Habronema
(Roundworm)

Life Cycle:
◦
◦
◦
◦
Adult stage is found in stomach
Larvae is passed which is ingested by house fly
House fly deposits eggs on lips of horse
Horse swallows eggs and they mature in
horses stomach
Habronema
(Roundworm)

Damage:
◦ Summer sores can
form if larvae are
deposited in open
wounds
◦ Disfigure horses
◦ Hard to heal

Symptoms:
◦ Presence of summer
sores
◦ Excessive tearing and
running of eyes
◦ Open sores
Lungworms
(Roundworms)
Affect circulatory system & lungs
 Host: All species of livestock

Lungworms
(Roundworms)

Life Cycle:
◦
◦
◦
◦
◦
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Eggs laid in lungs of animals
Coughed up & swallowed
Eggs hatch in stomach and larvae are passed
Develop in moist earth or water
Ingested by animal
Burrow into lymph nodes and are carried to lungs
where they mature
Lungworms
(Roundworms)

Damage:
◦ Mechanical blockage
of lungs
◦ Collapse of infected
area
◦ Blockage of windpipe
and bronchea

Symptoms:
◦ Coughing
◦ Fast or forceful
breathing
◦ Fever
◦ Animal reluctant to
move
◦ Goes off of feed and
water
Tapeworms

Less important than roundworms

3 species of tapeworms
◦ Broad tapeworm
◦ Beef tapeworm
◦ Pork tapeworm
Broad Tapeworm
Host: All classes of
livestock and also in
man
 Reach up to 10 feet
in length


Life Cycle:
◦ Adult lives in small
intestine
◦ Segments containing
eggs break off and pass
out of animal
◦ Eggs are eaten by
oribated mite
◦ Mites are eaten by
host and eggs hatch in
small intestine
Broad Tapeworm

Damage:
◦ No physical damage
◦ Tapeworm is in
competition with
animal for food.

Symptoms
◦ Weight loss
◦ Diarrhea
◦ emaciation
Beef and Pork Tapeworm
Both are similar and almost identical
 Host:

◦ Beef tapeworm- cattle and man
◦ Pork tapeworm- swine and man
◦ Man is necessary intermediate host

Reach 5 feet in length
Beef and Pork Tapeworm

Life Cycle:
◦ Adult lives only in man
◦ Eggs contaminate the feed of animal through human
contact
◦ Animal ingests feed and eggs pass to intestinal wall
◦ Larvae lodge in some muscle causing a cyst
◦ Passed back to man when infected meat is eaten
Beef and Pork Tapeworm

Damage:
◦ Little economic
damage to cattle
◦ Causes mealy beef

Symptoms:
◦ No visible symptoms
except when animal is
slaughtered
Flukes
Several species
 Liver Fluke is the most important

Liver Fluke

Host:
◦ Parasite of cattle, sheep, goats, and man
◦ Damaging to young animals
Liver Fluke

Life Cycle:
◦
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◦
◦
◦
◦
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Adult lives in bile ducts
Eggs passed into intestines and passed out
Eggs must be in water to hatch
Larvae hatch and seek a snail
Larvae develops on snail and then attaches to a plant
Animals ingest infected plant
Flukes pass to intestines and burrow through
abdominal cavity to the lungs.
Liver Flukes

Damage:
◦ Irritation and
thickening of bile duct
◦ Fibrosis of the liver

Symptoms:
◦ Anemia
◦ Weight loss
◦ Death if not treated.
Tomorrow

We will go over control methods of
internal parasites.