Day 1: Strongyle Flashcards
What is the most important parasites in horses and the phylum name
Strongyles and the phylum is Nemathelminthes
Where are small and large strongyles located
Worldwide
Where are Strongyles located in the horse
Cecum and colon
What are the physical exam findings of a horse with Strongyles
Muscle Wasting
Thin
Poor hair coat
Depressed
Failure to grow
How do horses acquire Strongyles
Through grazing on infectious L3
What is the generalized Life Cycle of Strongyle
Direct life cycle-No intermediate host
How do large strongyles cause damage
By migrating larvae and adults “plug feeding”
Anterior ends of adults have large buccal capsules with teeth
What are the 3 types of Strongyles
Strongyle vulgaris
Strongyle edentatus
Strongyle equinus
What may Strongyle vulgaris look like
Large sized adult worms (2-3 inches)
Have teeth
Suck blood
May appear red in color
Explain the epidemiology of Strongyle vulgaris
Infective L3 are acquired on pasture during grazing
More common in young horses
What is the prepatent period of Strongyle vulgaris
6-7 months
Explain in detail the Strongyle Vulgaris life cycle starting with the ingestion
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
How does the Large Strongyle migrate in the horse?
The horse GI tract folds back on itself allowing larvae to re-enter the GI tract by penetrating the cecal wall
What is the pathology of strongyle vulgaris
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
What are the clinical symptoms of a horse with Large Strongyles
Colic-Due to decreased motility, secondary thromboembolic episodes
Rise in body temperature
Anorexia
Weight loss
Depression
Reluctance to move
How long is the prepatent period for Strongyle edentatus
11-12 months
What is the Strongyle Edentatus lifecycle in detail
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
Where is the Strongyle edentatus located
Ceum and colon
How long is the prepatent of Strongyle Equinus
9 months
What are the clinical signs of S. edentatus or S. equinus
Low-grade fever
Inappetence
Depression
Diarrhea
Sometimes constipation/low fecal output
Abnormal gut motility can cause mild colic
What is the detailed life cycle of Strongyle Equinus
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
What is the pathology of S. edentatus or S. equinus
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
What are small strongyle called
Cyathostomes
What is the life cycle of small strongyle
Direct life cycle
L4 larval stage develops in the colonic mucosa, no tissue migration
Affect foals early because their prepatent period
What is the prepatent period of small strongyles
6-10 weeks
What is the pathology of small strongyles
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
What are the clinical signs of small strongyles
Large numbers of L4 larvae encysted in the colon wall
Severe colic
Diarrhea
Anorexia
Emaciation
Can be asymptomatic
What is the treatment of small strongyle encysted larvae
Moxidectin, panacur
Diagnosis of Equine Nematodes
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)
Which environment favors large and small strongyles
Moist warm environment favors rapid development
More infective larvae produced and surviving, a shorter life cycle and higher worm burdens in the summer months
When does transmission decline in small and large strongyles
Transmission declines as the temperature decreases in Fall and Winter
Dry periods in mid summer also kill L3 larvae on pasture
What is the control of Equine GI parasites
PPPP
Permanent pasture promotes parasitism
Control pasture
Rotational grazing
Pasture sweeping
Plowing and reseeding
