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VM638: Parasitology > Horses (Exam 2) > Flashcards

Horses (Exam 2) Flashcards

1
Q

What is the taxonomy of equine strongyles?

A

Nematode
Two groups: large and small

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2
Q

What is the geographic distribution of equine strongyles?

A

Worldwide

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3
Q

Where are equine strongyles located in the host?

A

GI tract

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4
Q

What is the diagnostic of choice for equine strongyle eggs?

A

Fecal flotation: eggs are “strongyle-type”
Larval culture
Eggs pass undifferentiated, can larvate in manure over time

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5
Q

What is the morphology of small equine strongyles?

A

Bright red L4s of immature adults (may be recovered on rectal palpation
Adults are white to red
Eggs: thin-walled but hold up well in the environment

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6
Q

What is the morphology of large equine strongyles?

A

Adults found in cecum and colon
Strongylus equinus: 2 pointed teeth-like structures
Strongylus vulgaris: rounded tooth-like structure
Strongylus edentatus: no teeth-like structures

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7
Q

What is the lifecycle of small equine strongyles?

A

Eggs are passed into environment and hatch
L1 -> L3 –> L3 ingested by horse –> larvae do not migrate extra-intestinally –> L3 penetrate mucosa and submucosa in colon and cecum to molt –> return to lumen for final maturation

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8
Q

What is the infectious stage of equine strongyles?

A

L3

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9
Q

What is the lifecycle of large equine strongyles?

A

Strongylus vulvaris: larvae penetrate mucosa of lg intestine –> molt to L4, then enter circulation –> migrate to cranial mesenteric artery to molt to immature adults
Strongylus edentatus: adults in cecum and colon; L3 ingested from environment –> 3rd stage larvae penetrate intestinal mucosa and migrate to liver via hepatic portal system –> molt to L4 –> further migration subperitoneally –> move back to GI tract

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10
Q

What are the environmental factors of equine strongyles?

A

In some regions, larvae can arrest development and eggs can overwinter on pasture

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11
Q

What are clinical signs of large equine strongyles?

A

Not usually significant (adults may cause diarrhea, anemia)
Larval S. edentatus and S. equinus can cause hemorrhagic tracts in liver and induce nodule formation in gut or peritoneum
Larval S. vulgaris most pathogenic: inflammation and thromboses of cranial mesenteric artery, iliac, celiac, and femoral arteries –> aneurysms; also thromboembolisms may lead to ischemic infarctions and ileus of colon –> fever, diarrhea, colic, lameness, death

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12
Q

What are clinical signs of small equine strongyles

A

Larval cyathostomosis: synchronous development of arrested larvae and emergence of L4s –> catarrhal or hemorrhagic enteritis and protein losing enteropathy
Pathology due to destruction of cells and thickened mucosa
Sudden onset of watery diarrhea, rapid weight loss, hypoalbuminemia, colic, and death

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13
Q

How are equine strongyles treated/controlled/prevented?

A

Resistance highly prevalent
Control needs to rely not only on anthelmintics but also on practices that protect “refugia”
Deworming by calendar NOT recommended
Fecal counts should guide decision-making
Management is key: reduce stocking density, co-graze other species, pick up fecals 2x/wk, maintain nutrition

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14
Q

Are equine strongyles zoonotic?

A

No

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15
Q

What is the taxonomy of parascaris equorum?

A

Nematode
Ascarid
Roundworm

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16
Q

What is the geographic distribution of parascaris equorum?

A

Worldwide

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17
Q

Where is parascaris equorum located in the host?

A

GI tract, small intestine

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18
Q

What diagnostic is best for parascaris equorum?

A

Fecal flotation

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19
Q

What is the morphology of parascaris equorum?

A

Thick, round, brown eggs
Huge!
3 lips

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20
Q

What is the life cycle of parascaris equorum?

A

Infective L3 develops within eggs
Transmission via infective eggs
Hepatic-pulmonary migration

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21
Q

What group is more impacted by parascaris equorum? What are the environmental factors?

A

More prominent in suckling/weanling foals
High fecundity of female worms and persistence of eggs

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22
Q

What are the clinical signs associated with parascaris equorum?

A

Migrating larvae: liver fibroses, petechial hemorrhage in lungs
Adults: catarrhal enteritis, obstruction, +/- perforation
Coughing, mucopurulent discharge, decreased feed intake, colic, pot-bellied appearance, diarrhea, death
Light infections in foals well-tolerated

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23
Q

How is parascaris equorum treated?

A

Benzimidazoles, ivermectin, pyrantel

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24
Q

Is parascaris equorum zoonotic?

A

No

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25
Q

What is the taxonomy of oxyuris equi?

A

Nematode
Equine pinworm

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26
Q

What is the geographic distribution of oxyuris equi?

A

Worldwide

27
Q

Where is oxyuris equi located in the host?

A

GI tract. cecum, colon, rectum

28
Q

How is oxyuris equi diagnosed?

A

Look for eggs using scotch tape pechnique

29
Q

What is the morphology of oxyuris equi?

A

Gray-white worms with long, pointed tail
Found in cecum, colon, rectum
Flattened on only one end

30
Q

What is the life cycle of oxyuris equi?

A

Females migrate to rectum and out anus –> cement eggs in perianal region –> L3 develops within egg –> environmental contamination –> eggs containing L3 are ingested –> final maturation takes place in large intestine

31
Q

What are the transmission dynamics/environmental factors of oxyuris equi?

A

Flakes of material containing eggs are dispersed in environment by rubbing
Little immunity to reinfection

32
Q

What clinical signs are associated with oxyuris equi?

A

Feeding of L4 may cause mucosal inflammation
Anal pruritus, rubbing at egg laying
“Rat-tail” appearance of tail

33
Q

How is oxyuris equi treated/controlled/prevented?

A

Stable hygiene: remove bedding frequently and avoid contamination of feed troughs with bedding
Anthelmintic administration + cleaning regularly under tail to remove egg masses

34
Q

Is oxyuris equi zoonotic?

A

No

35
Q

What is the taxonomy of eimeria leuckarti?

A

Apicomplexan

36
Q

What is the geographic distribution of eimeria leuckarti?

A

worldwide

37
Q

Where is eimeria leuckarti located in the host?

A

GI tract

38
Q

What is the host of eimeria leuckarti?

A

Equids

39
Q

What diagnostics are used for eimeria leuckarti?

A

Diagnosis difficult due to heavy nature of oocysts
Sheather’s sugar

40
Q

What is the morphology of eimeria leuckarti?

A

Oocysts are ovoid or pyriform with a flattened end
Thick, dark shell and micropyle

41
Q

What is the lifecycle of eimeria leuckarti?

A

Similar to other GI coccidians
Merogony and gametogony within the GI tract, with sporulation (sporogony) occurring in the environment - timing dependent on environmental factors

42
Q

Diagram the lifecycle of eimeria leuckarti

A
43
Q

What are the transmission dynamics/environmental factors of eimeria leuckarti?

A

As with many other apicomplexans, oocysts are passed unsporulated and take time in the environment to sporulate and become infectious

44
Q

What are the clinical signs of eimeria leuckarti?

A

Intermittent diarrhea, but otherwise not overly pathogenic

45
Q

How is eimeria leuckarti treated/controlled/prevented?

A

Monitor environmental contamination

46
Q

Is eimeria leuckarti zoonotic?

A

No
Highly host specific

47
Q

What is the taxonomy of anoplocephala perfoliata?

A

Cestode
Tapeworm

48
Q

What is the geographic distribution of anoplocephala perfoliata?

A

Worldwide

49
Q

What is the location of anoplocephala perfoliata in the host?

A

GI tract
Terminal ileum, cecum

50
Q

What is the morphology of anoplocephala perfoliata?

A

Small, rounded scolex and lappets behind the four suckers
No rostellum, no hooks
Eggs are spherical or triangular with pyriform apparatus

51
Q

What is the life cycle of anoplocephala perfoliata?

A

Adults live in GI tract
Oribatid mites serve as typical intermediate host (Cysticercoid larval form)

52
Q

What are the clinical signs of anoplocephala perfoliata?

A

Relatively non-pathogenic, but heavy infections may cause severe clinical signs +/- fatality
May see unthriftiness, enteritis, colic

53
Q

What is the pathogenesis of anoplocephala perfoliata?

A

Found at ileocecal junction
Ulceration of mucosa
Lesions may lead to intussusception
Obstruction and perforation are also possible

54
Q

What is the taxonomy of gasterophilus intestinalis?

A

Equine stomach bots

55
Q

What is the geographic distribution of gasterophilus intestinalis?

A

worldwide

56
Q

Where is gasterophilus intestinalis located in the host?

A

GI tract

57
Q

What is the host of gasterophilus intestinalis?

A

Equids

58
Q

What is the morphology of gasterophilus intestinalis?

A

Robust, dark flies
Larvae are cylindrical, reddish/orange with posterior spiracles
Eggs easily seen, stimulated to hatch by warmth, grooming

59
Q

What is the life cycle of gasterophilus intestinalis?

A

Obligate parasites of equids and pachyderms
Eggs laid on hair of forelegs
Several eggs laid on each hair (1000 eggs laid by one female in a span of a few days

60
Q

When are adult gasterophilus intestinalis most active?

A

In late summer

61
Q

What is the pathogenesis/clinical signs associated with gasterophilus intestinalis?

A

Burrowing of 1st and 2nd stage larvae in mouth, tongue, and gums can cause lesions +/- secondary bacterial infections
Cluster at boundary of glandular and non-glandular epithelium of stomach
Pass in feces, pupate in environment

62
Q

What are other species of gasterophilus?

A

G. nasalis
G. hemorrhoidalis

63
Q

How is gasterophilus intestinalis prevented/controlled?

A

Remve eggs from coat, especially around lips

64
Q

Is gasterophilus intestinalis zoonotic?

A

No

VM638: Parasitology (22 decks)

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