External Parasites

External Parasites
Biting insects that suck blood
Vectors of encephalomyelitis
____ _____ hatches into maggots which feed on dead tissue
Lifecycle stages are: egg, larva, pupa, adult
Best way to control is to remove manure and decaying vegetable material
There are both biting and sucking kind
Attach eggs, called nits, to the hair, close to skin
Eggs hatch in 11-20 days
Females lay eggs 11- 12 days of age
Can only exist about 3 days when off the host animal
Treat by spraying, sponging or dusting and repeat in 2-3 weeks
Cause mange
So small must be viewed under microscope
Chorioptic type may cause foot mange resembling scratches
Females lay 10 to 25 eggs during laying period which lasts 12-15 days
Eggs hatch in 3-10 days
Dust is not effective, must spray or use a wet brush wash,
repeat every 7 days
Cause piroplasmosis
The _____ ________ caused African horse fever
Lifecycle stages are: egg, 6 legged larva or seed tick, 8 legged
nymph, adult
Treat by dipping entire animals
Breathe by spiracles or holes on their abdomen
Caused by various species of fungi, arranged in circles on the skin
Causes severe itching, infection may lead to abscesses
Lesions are usually covered with grayish crusts
Treat with warm soap and water to soften crusts, paint with tincture of
iodine daily for 1 – 2 weeks
The disease this parasite causes can be spread to children
External Parasites
Bot Fly
Internal Parasites
Lays yellow eggs on legs, chest, belly and neck.
Also chin, throat, nostrils and lips.
Horse licks or bites stimulating hatching of eggs
Larvae burrow into the tongue and travel to the stomach
Mature in stomach in 9 months
Mature larvae burrow into the ground, turn into pupa and in 1517 days they emerge to begin the cycle again
Active from early spring to first freeze
Treated with anthelmintic
Cycle must be broken by killing the flies, egg removal or
Swallowing eggs in feed, pasture and water infects young horse
Larvae migrate to small intestine, liver and lung tissue
Cause digestive problems, intestinal and blood vessel blockage, colic
and possibly death
Measure 5 to 22 inches in length
Lifecycle is about 3 months
Female worms lay up to 200,000 eggs per day
Deworm foals every two months for 1st year to prevent
Unthriftiness, pot belly, rough coat, lack of growth and cough
are signs of infestation
Ascarids (Roundworms)
Primarily affects young horses
Most common form of equine internal parasites
Found in large intestine
Lays several thousand eggs per day
Larvae climb to upper portions of pasture grasses and are
swallowed by horses grazing
Large strongyle larvae migrate into arties and cause blood clots
Small strongyles migrate thru liver and large intestine causing
diarrhea and colic
Infests young foals that ingest larvae in the dams milk or by larvae in
Larvae migrate through lungs and small intestine
Foals become dehydrated and developer chronic diarrhea
White-appearing worms with long slender tails
Seen in feces of affected horses
Worms mature in large intestines and females full of eggs travel to
small colon, rectum and crawl out anus
Causes horse to rub tail against posts, this crushes the adult but
leaves eggs glued to anal region
Ascarids (Roundworms)
Bot Fly
Internal Parasites

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