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PARASITOLOGY - 2 > 10 – Horses Helminths I > Flashcards

10 – Horses Helminths I Flashcards

1
Q

What is the location of Drascheia spp. and Habronema spp.? (gastric nematodes)

A
  • Drascheia spp. – submucosa
  • Habronema spp. – mucosa
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2
Q

Drascheia spp./Habronema spp.

A
  • Spirurid stomach worms
  • NOT in Canada
    o Unless imported horses from warmer parts of the world
  • Arthropod transmitted
    o Stomoxys calcitrans (stable fly)
    o Musca domestica (house fly)
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3
Q
A

Drascheia spp

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4
Q
A

Habronema spp.

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5
Q

Drascheia spp./Habronema spp. lifecycle

A
  • Larvae ingested by horses
  • Adult stages live enclosed in mucosal surface of stomach
  • Female produces eggs with L1 excreted in hosts feces
  • IH: maggots of flies living in manure ingest L1
    o L1 to L3
  • L3 in IH migrates to head and are transmitted when flies are feed on lips, nostrils or skin lesions of DH=dead end, but get habronematidosis
  • OR swallowed larvae go into stomach mucosa to eventually evolve as adults
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6
Q

Drascheia spp./Habronema spp. clinical signs

A
  • Cutaneous habronemiasis (‘summer sores’)
  • *when larvae invade wounds
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7
Q

Drascheia spp./Habronema spp. diagnosis

A
  • Larvae in skin scraping or biopsy
  • Adults on gastric lavage/scoping
  • NOT fecal float: eggs disintegrate rapidly in feces
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8
Q

Drascheia spp./Habronema spp. treatment

A
  • Ivermectin (ML)
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9
Q

What is the pathogenesis of equine stomach nematodes ?

A
  • Not in the stomach, just in the topical injuries (granulomas, ‘summer sores’)
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10
Q

What are the small intestine nematodes?

A
  • Parasaris spp.: *large round worm of horses
    o P. equorum
    o P. univalens
  • Strongyloides westeri
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11
Q

Ecology/epidemiology of Parascaris

A
  • Primarily patent in FOALS <6 months of age
    o 50% of foals have them
  • Occasionally in adult horses (especially older horses in their late 20s)
  • Worldwide distribution
  • Pastured and stabled animals
  • Eggs are very RESISTANT and STICKY
  • Quasi-vertical transmission (mechanical)
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12
Q

Parascaris spp. life cycle

A
  • Egg with L3 ingested: HEPATO-TRACHEAL MIGRATION
    o Respiratory signs (coughing in foals)
  • Eggs with morula in feces
  • Eggs with L1-L2
  • Egg with l3
  • *PPP 10-12
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13
Q

Parascaris spp. egg

A
  • Sticky, thick, rough shell with morula inside
  • *transmit well in stables and on pasture
  • If older or agitated too much=loss shell
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14
Q

Parascaris spp. pathogenesis and clinical signs

A
  • Often asymptomatic
    o Reduced growth
    o Physical blockage
    o Possibly rupture of intestine
  • Respiratory signs in foals
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15
Q

Parascaris spp. diagnosis

A
  • Foals: look for respiratory signs
    o Treat regardless of fecal floation (not continuous egg shedding)
  • Adults: shedding eggs may suggest other health issues
  • *look in feces
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16
Q

Strongyloides westeri

A
  • *Equine threadworm
  • Pharynx 1/3 of body
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17
Q

Ecology/epidemiology of Stronglyoides westeri

A
  • Primarily patent in FOAL <6months of age
  • Worldwide distribution
  • Warm humid climates: BC
  • Pastured and stabled animals with suboptimal environmental hygiene
  • Eggs NOT particularly resistant
  • *vertical transmission: TRANSMAMMARY (shed in milk for up to 8 weeks)
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18
Q

Strongyloids westeris: young horses lifecycle

A
  • *semi-tracheal or tracheal migration
  • *larvated eggs in feces
    o Homogonic cycle: back into mare
    o Heterogonic cycle: free living adults producing in environment
19
Q

Strongyloids westeris: older horses

A
  • Semi-tracheal, tracheal and SOMATIC migration
  • From somatic=larvae in tissues to larvae in COLOSTRUM AND MILK
20
Q

Foals prevention of Strongyloids westeri

A
  • Treat mare to prevent transmammary infection
21
Q

Diagnosis of Strongyloides westeri

A
  • Floatation on fresh FOAL FECES (look for eggs)
22
Q

Pathogenesis of Strongyloids westeri

A
  • Cutaneous lesions
  • Respiratory signs in foals
  • Diarrhea in young foals (2 weeks)
    o Roto, clostridium, etc.
23
Q

Treatment of Strongyloides westeri

A
  • Mare: just before foaling
  • Foal: 1 week of age if you know it’s a problem
24
Q

What are the large intestine nematodes?

A
  • Strongylus spp.
  • Cyathostomes=small strongyles
25
Q

Large intestinal nematodes: Strongylus spp.

A
  • Strongylus vulgaris: blood worm (b/c of where they travel to)
  • Strongylus edentates
  • Stronglyus equinius
  • *virtually eradicated worldwide due to antihelmintic use, but it is appearing
  • *pasture transmitted
26
Q

How do you differentiate between S. vulgaris and S. equinius eggs?

A
  • Both strongyle=impossible to differentiate just using fecal float
  • *coproculture and L3 morphology and/or PCR (nemabiome approaches)
27
Q

Migratory large strongyles: differentiation

A
  • Hard to differentiate between them
28
Q

Buccal capsule S. vulgaris

A
  • Two rounded teeth
    o Irritate intestinal mucosa but not major cause of pathogenesis
29
Q

What is the lifecycle of Strongylus vulgaris?

A
  • L3 ingested
  • Moult to L4 in wall of large intestine
  • Migrate into arteries of large intestine and travel via vascular endothelium to rot of the CRANIAL MESENTERIC ARTERY
    o stay there for months
  • then L5 return to arterial lumen and travel back to large intestine and develop to adults
  • Eggs with morula in feces
30
Q

Strongylus edentates buccal capsule

A
  • *no teeth
31
Q

S. edentatus lifecycle

A
  • L3 ingested
  • Travel via portal circulation where they moult to L4
  • Then through hepatic ligaments to mesentery where they stay for months
  • Then L5 travel to large intestine and develop to adults in the lumen
32
Q

What is the prepatent period of S. edentatus?

A
  • 1 year
33
Q

S. equinus buccal capsule

A
  • Least common (except on stable island, NONE in SK)
  • *Bifid tooth and teeth
34
Q

S. equinus lifecycle

A
  • L3 ingested
  • Moult to L4 in wall of large intestine
  • Migrate through peritoneal cavity to liver and pancreas
    o Stay for months
  • then L5 migrate back into large intestine and develop to adults in lumen
35
Q

How do you diagnosis Strongylus spp.?

A
  • Strongyle type eggs in fecal floatation
  • Differentiation: larval culture (2 weeks to grow them) OR DNA sequencing
    o More cyanostomes as they age=have developed a strong immunity to strongyles
36
Q

What health issues can S. vulgaris cause?

A
  • verminous arteritis (associated with larvae)
  • ischemic necrosis of intestine
  • colic
37
Q

What health issues can S. equinus cause?

A
  • No symptoms associate with adults
  • Larvae occasionally found in strange places in abdomen (cryptorchid testes)
  • May cause pancreatic damage
38
Q

Cyathostomes

A
  • Small strongyles=trichonemes
  • Most abundant and diverse equine nematodes
  • At least 60 known species
  • Cecum and colon
  • Pasture transmitted
39
Q

Cyathostome buccal capsule

A
  • Small buccal capsule
  • NO teeth at base
40
Q

Cyathostomes life cycle

A
  • Eggs shed (L1 to L3 over a couple weeks)
  • Ingested during grazing season
  • Hypobiosis (L4) in winter: big cause of pathogenesis
    o Often cause colic in spring
  • **PPP: 2-3 months
41
Q

What are the clinical signs of equine cyathostomisasis?

A
  • Simultaneous emergence of mucosal larvae (rare in Canada)
  • Diarrhea, weight loss, protein losing enteropathy, edema
  • *mortality as high as 50%
  • *can occur in ABSENCE of any eggs shed in feces
42
Q

What is the diagnosis for cyathostomes?

A
  • Subadult and adult worms in feces
  • Larval culture (+/- PCR) from eggs in feces
  • Thickened walls of large intestine on ultrasound
43
Q

What is the treatment for cyathostomes?

A
  • *MOXIDECTIN: only product effective against inhibited larvae
  • *treat in FALL to prevent mass emergence in spring
  • Egg reappearance period (ERP) following treatment varies with product
    o Due to mobilization of inhibited larvae
44
Q

Equine nemabiome

A
  • Fecal egg count does not give whole picture of how sick it may be
  • *still work in progress

PARASITOLOGY - 2 (13 decks)

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