Horses: Ascarids, Pinworms, Draschia/ Habronema

Question 1

parascaris equorum morphology

Answer 1

equine ascarids
large stout worms
anteior opening w/ 3 lips
adults parasitic in S.I

Question 2

parascaris equorum lifecyle

Answer 2

direct
infection by ingesting larvated eggs in contaminated pasture
tracheal/ somatic migration
parasite of foals
prepatent period 12 weeks
Golden brown, round, sticky eggs

Question 3

parascaris equorum clinical signs

Answer 3

diarrhea
enteritis
respiratory issues and nasal discharge
dull hair & poor growth
extreme infections can be fatal!!

Question 4

How can infection lead to death

Answer 4

large worm burden
worms grow faster than intestinal tract in foals
impaction colic
intestinal perforation and rupture

Question 5

parascaris equorum treatment/ control

Answer 5

clean mares udder/ teats (clean nursing environment)
dedicated pastures for foals
-grazed by older animals with low FEC
drug therapy 2,4,6,8 months
-FBZ, pyrantel, macrocylic lactone

Question 6

oxyuris equi morphology

Answer 6

equine pinworm
medium sized worms
long tail w acute distal end
muscular bulb esophagus
adults parasitic in cecum, small and large colon
horses of all ages affected

Question 7

oxyuris equi lifecycle

Answer 7

direct
infection via ingesting embryonated egg
larvae hatch, penetrate colon, develop, return to lumen & reproduce
females deposit eggs perianal folds
5 month prepatent period
eggs flake off skin and adhere to objects
infective 4-5 days after development

Question 8

oxyuris equi clinical signs

Answer 8

intense anal pruitis and itching
rubbing hind end
broken tail hair
behavioral issues

Question 9

does oxyuris equi need to be differentiated from mange

Answer 9

YES

Question 10

oxyuris equi diagnosis

Answer 10

oval/ elongate egg
“scotch tape” microscope slide
egg mass in tail hair resembles shaving cream

Question 11

oxyuris equi treatment/ control

Answer 11

adult worms susceptible to treatment
-Pyrantel and IVM effective
no evidence durg resistance
successful treatment and attention to hygiene

Question 12

strongyloides westeri

Answer 12

equine threadworm
small adult worms in S.I
-only females parasitic
homogonic and hetergonic lifecycle
foals infected via lactogenic route
-prepatent period 7 days!
also infected via ingestion L3 and percutaneous

Question 13

are males parasitic for strongyloides westeri

Answer 13

NO! only females

Question 14

strongyloides westeri clinical significance

Answer 14

primarily infection of foals
-eggs disappear from feces by 24 weeks
-Arrested in tissue for LIFE

Question 15

strongyloides westeri clinical signs and treatment

Answer 15

diarrhea-dehydration
poor growth
treatment to remove adults S.I, supportive care

Question 16

Draschia & Habronema

Answer 16

equine stomach worms
small worms
thin shell larvated eggs occasionally seen on fecal
penetrate mucosa and develop in stomach

Question 17

Draschia & Habronema lifecycle

Answer 17

obligate indirect
transmission of infected larvae by fly intermediate
larvae in cutaneous wounds, warm/moist openings
adults in stomach, eggs/larvae passed in feces
-ingested by maggots, larvae grow to infective as fly develops
prepatent period 5 months

Question 18

Draschia & Habronema clinical significance

Answer 18

disease process associated w deposition of larvae by fly
cutaneous harbronemiasis
granulomatous lesion
adult worms live in fibrotic nodules in stomach
worldwide distribution! IVM made rare
-fly control important
-single dose macrocyclic lactone sufficient

Question 19

is there age associated immunity with parascaris

Answer 19

YES

Question 20

t/f parascaris can infect foals if they ingest larvated eggs shed by previous years foals

Answer 20

TRUE

Question 21

can an object, like a curry comb, facilitate spread of oxyuris

Answer 21

YES

Question 22

which of these parasites is spread by an intermediate host?

Answer 22

equine stomach worms