Strongyloids & Cyathastomes of Horses (8)

Question 1

Small strongyles are also called _______

Answer 1

cyathostomes

Question 2

Strongyles in the horse are found in the ______ (location in body)

Answer 2

colon/large intestine

Question 3

Strongyles in the horse have a [direct/indirect] lifecycle by ingestion of _______

Answer 3

L3 while grazing contaminated pasture

Question 4

What parasite is the primary target for control by equine owners?

Answer 4

strongyles - can be deadly when uncontrolled

Question 5

Large strongyles have what morphology in horses?

Answer 5

female worms always bigger
sexually dimorphic
males with copulatory bursa
prominent buccal capsule

Question 6

What are the basic lifecycle characteristics of large strongyles?

Answer 6

eggs based in feces develop to L3 on pasture ~2 weeks
L3 ingested while grazing

Question 7

Larvae of large strongyles migrate ______

Answer 7

extra-intestinally

Question 8

Large strongyles have [short/long] pre-patent periods

Answer 8

long

Question 9

Which strongyle has the shortest pre-patent period?

Answer 9

strongylus vulgaris

Question 10

Define strongylus vulgaris

Answer 10

larvae migrate in walls of small armies and anterior mesenteric artery
arrive in cecum/colon and mature and reproduce
6 months

Question 11

Where do strongylus equinus migrate?

Answer 11

in peritoneal cavity and liver
arrive in cecum/colon and mature and reproduce
8 months

Question 12

Where do strongylus edentatus migrate?

Answer 12

migrate in peritoneal cavity and live
arrive in cecum/colon and mature and reproduce
12 months

Question 13

What is the clinical importance of large strongyles in horses?

Answer 13

disease in older foals occurs in the pre-patent period
pathology associated with the larval stages during long extra-intestinal migration

Question 14

Which strongyle is the most pathogenic by migration through the arteries?

Answer 14

s. vulgaris
have aneurysm and infarction

Question 15

Because of large strongyles, horses get _____ by interruption of blood supply

Answer 15

colic

Question 16

T/F: Adult large strongyles suck blood but that is not the most important feature about them

Answer 16

TRUE

Question 17

T/F: Adult large strongyles can have a negative fecal exam

Answer 17

TRUE

Question 18

How do you diagnose large strongyles in horses?

Answer 18

clinical signs, age, risk factors
wormy pastures
over-crowding
association with older animals with high FEC
no consistent worming program

Question 19

What is the basic morphology of small strongyles?

Answer 19

sexually dimorphic - males with copulatory bursa
anterior end with prominent LEAF CROWN “corona radiate”

Question 20

Where are small strongyles found in the horse?

Answer 20

large intestine

Question 21

What is the basic lifecycle of small strongyles?

Answer 21

eggs passed in fever develop to L3 on pastures ~2 weeks
ingested during grazing
larvae penetrate and encyst in intestinal wall
late L3 emerge from intestinal wall, develop to L4 and become adult reproducing worms
eggs in feces @9 weeks post infection without seasonally mediated arrested development
9 week pre-patent period

Question 22

What is the clinical importance of small strongyles?

Answer 22

disease in foals occurs BEFORE adult worms are sexually mature
associated with the mass emergence of encysted parasites from wall of large intestine

Question 23

What is a cause of foal heart diarrhea?

Answer 23

small strongyles
fecal exams can be negative

Question 24

What are risk factors of small strongyles?

Answer 24

wormy pasture
over-crowding
association with older animals w/ high FEC
no consistent worming programt

Question 25

What is the clinical disease of small strongyles?

Answer 25

red worms (l4) often passed in feces following emergence
often observed on gloves when palpating infected horses
not to be confused w/ pinworms

Question 26

There are ___ species of large strongyles

Answer 26

3

Question 27

How do you diagnose strongyles?

Answer 27

detection of eggs by fecal flotation
large and small morphologically indistinguishable

Question 28

Egg reappearance for cyathostomes is as short as ____ days and for others ___ to _____ weeks

Answer 28

28
6
12
depends on species

Question 29

What is the erp for large strongyles

Answer 29

6
8
12
months

Question 30

Fecal Egg Counts are useful for

Answer 30

monitoring drug effectiveness
pasture contamination
identification of “wormy” high egg shedding animals

Question 31

T/F: Fecal egg counts can be used to predict worm burdens

Answer 31

FALSE

Question 32

What are the 3 current deworming products for horses?

Answer 32

benzimidazole
imidazothiazole/tetrahydropyrimidines
macrocyclic lactones (ivermectin, moxymectin)

Question 33

For the deworming products there is no resistance in [large/small] strongyles

Answer 33

large

Question 34

How do you have pharmacologic control of strongyles in horses?

Answer 34

interval dosing (most common) - treatment of all horses at fixed intervals throughout the year, no diagnostics
**suppressive deworming to minimize contamination
strategic dosing - fixed times of the year, no diagnostics
continuous daily treatment
selective treatment
review these slides in notes I would say

Question 35

Horses are more at risk when they have a __________ season

Answer 35

active grazing

Question 36

What is refugia?

Answer 36

the portion of parasite population not subject to drug selection pressure