Day 1: Strongyle

Question 1

What is the most important parasites in horses and the phylum name

Answer 1

Strongyles and the phylum is Nemathelminthes

Question 2

Where are small and large strongyles located

Answer 2

Worldwide

Question 3

Where are Strongyles located in the horse

Answer 3

Cecum and colon

Question 4

What are the physical exam findings of a horse with Strongyles

Answer 4

Muscle Wasting
Thin
Poor hair coat
Depressed
Failure to grow

Question 5

How do horses acquire Strongyles

Answer 5

Through grazing on infectious L3

Question 6

What is the generalized Life Cycle of Strongyle

Answer 6

Direct life cycle-No intermediate host

Question 7

How do large strongyles cause damage

Answer 7

By migrating larvae and adults “plug feeding”
Anterior ends of adults have large buccal capsules with teeth

Question 8

What are the 3 types of Strongyles

Answer 8

Strongyle vulgaris
Strongyle edentatus
Strongyle equinus

Question 9

What may Strongyle vulgaris look like

Answer 9

Large sized adult worms (2-3 inches)
Have teeth
Suck blood
May appear red in color

Question 10

Explain the epidemiology of Strongyle vulgaris

Answer 10

Infective L3 are acquired on pasture during grazing
More common in young horses

Question 11

What is the prepatent period of Strongyle vulgaris

Answer 11

6-7 months

Question 12

Explain in detail the Strongyle Vulgaris life cycle starting with the ingestion

Answer 12

L3 is ingested and is in the SI and penetrates the intestinal wall where it molts into L4
L4 migrates upstream in artieroles within intima toward cranial mesenteric artery
L4 stays in cranial mesenteric artery for up to 120 days
L4 migrates from artioles to colon wall where it produces nodules
nodules rupture releasing larvae into lumen where they mature to the adult stage

Question 13

How does the Large Strongyle migrate in the horse?

Answer 13

The horse GI tract folds back on itself allowing larvae to re-enter the GI tract by penetrating the cecal wall

Question 14

What is the pathology of strongyle vulgaris

Answer 14

Creates occlusion of blood flow and block blood flow from the bowel
Artiel damage can lead to thromboembolism and reduce blood flow in the bowel
Arterial

Question 15

What are the clinical symptoms of a horse with Large Strongyles

Answer 15

Colic-Due to decreased motility, secondary thromboembolic episodes
Rise in body temperature
Anorexia
Weight loss
Depression
Reluctance to move

Question 16

How long is the prepatent period for Strongyle edentatus

Answer 16

11-12 months

Question 17

What is the Strongyle Edentatus lifecycle in detail

Answer 17

L3 is ingested and exsheaths in SI
L3 penetrates intestinal wall
L3 migrates to the liver via portal veins
L3 molts to L4 in liver
L4 stays in liver for 9 weeks
L4 migrates in abdominal connective tissue
L4 produces nodules in large intestine and ruptures releasing larvae into the lumen of the colon

Question 18

Where is the Strongyle edentatus located

Answer 18

Ceum and colon

Question 19

How long is the prepatent of Strongyle Equinus

Answer 19

9 months

Question 20

What are the clinical signs of S. edentatus or S. equinus

Answer 20

Low-grade fever
Inappetence
Depression
Diarrhea
Sometimes constipation/low fecal output
Abnormal gut motility can cause mild colic

Question 20

What is the detailed life cycle of Strongyle Equinus

Answer 20

L4 migrates along the peritoneum to the liver
L4 stays in the liver for 6-7 weeks
L4 emerges at the hepatic ligaments
L4 migrates in the pancreas and associated organs

Question 21

What is the pathology of S. edentatus or S. equinus

Answer 21

Infected horses have liver damage due to larval migration
migrating larvae are less pathogenic than S. vulgaris
Adults are attached to the mucosa and plug feed/suck blood

Question 22

What are small strongyle called

Answer 22

Cyathostomes

Question 23

What is the life cycle of small strongyle

Answer 23

Direct life cycle
L4 larval stage develops in the colonic mucosa, no tissue migration
Affect foals early because their prepatent period

Question 24

What is the prepatent period of small strongyles

Answer 24

6-10 weeks

Question 25

What is the pathology of small strongyles

Answer 25

Damage is caused by adult worms L4 larvae in the large intestine Less pathogenic than large strongyles because buccal capsule is smaller and there they take smaller bites

Question 26

What are the clinical signs of small strongyles

Answer 26

Large numbers of L4 larvae encysted in the colon wall Severe colic Diarrhea Anorexia Emaciation Can be asymptomatic

Question 27

What is the treatment of small strongyle encysted larvae

Answer 27

Moxidectin, panacur

Question 28

Diagnosis of Equine Nematodes

Answer 28

Fecal flotation Strongyle-type eggs Cannot distinguish small and large strongyle infections ELISA test used for S. vulgaris to detect migrating larval stages (Damage by L4s)

Question 29

Which environment favors large and small strongyles

Answer 29

Moist warm environment favors rapid development More infective larvae produced and surviving, a shorter life cycle and higher worm burdens in the summer months

Question 30

When does transmission decline in small and large strongyles

Answer 30

Transmission declines as the temperature decreases in Fall and Winter Dry periods in mid summer also kill L3 larvae on pasture

Question 31

What is the control of Equine GI parasites

Answer 31

PPPP Permanent pasture promotes parasitism Control pasture Rotational grazing Pasture sweeping Plowing and reseeding