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Parasitology > Equine Nematodes > Flashcards

Equine Nematodes Flashcards

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1
Q

Drashia megastoma-Hosts

Habronema spp.

A

Equine

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2
Q

Drashia megastoma-Identification

Habronema spp.

A

D. megastoma-Adults: 13mm long, funnel-shaped buccal cavity, nodules close to the margo plicatus
Habronema spp.-Adults: 22-25 mm long, cylindrical buccal cavity
Eggs: Thin-shelled, larvated, 40-55 x 8-16 um

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3
Q

Drashia megastoma-Life Cycle

Habronema spp.

A

Indirect.
IH: Diptera Muscidae, Musca spp., Stomoxys calcitrans
L3 infective stage
Adults/larvae in stomach
larvae also in skin (“wrong place at wrong time”)

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4
Q

Drashia megastoma-Pathogenesis and Lesions

Habronema spp.

A 
Larvae
-cutaneous habronemiasis and cutaneous draschiasis
-granular conjunctivitis
Adults
-nodules in stomach
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5
Q

Drashia megastoma-Site of Infection

Habronema spp.

A

Adults/larvae in stomach

L3 in skin = “wrong place at wrong time”

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6
Q

Draschia megastoma-Clinical Signs

Habronema spp.

A

Larvae cause “summer sores”

Adults cause gastritis

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7
Q

Draschia megastoma-Diagnosis

Habronema spp.

A

Biopsy or skin-scraping of lesions to reveal larvae

Eggs difficult to recover in feces

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8
Q

Draschia megastoma-Treatment and Prevention

Habronema spp.

A

MCLs approved
Fly control
Ivermectin no longer effective-Resistance?

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9
Q

Parascaris equorum-Hosts

A

Equine

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10
Q

Parascaris equorum-Identification

A

Adults: Long, 30cm, white to cream colored, 3 large lips
Eggs: thick-walled, 90um

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11
Q

Parascaris equorum-Life Cycle

A

Direct. PPP = 10-12 wks
Direct and Per Os
No transmammary or transplacental transmission
L2 in egg is infective is swallowed→ hepatic-tracheal migration→ devel. to L3 in trachea→ swallowed→ devel. to L4 and migrate to small intestine→ adult

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12
Q

Parascaris equorum-Site of Infection

A

Small Intestine

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13
Q

Parascaris equorum-Pathogenesis and Lesions

A

Perforation, intestinal obstruction, unthriftiness or production losses

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14
Q

Parascaris equorum-Clinical Signs

A

Coughing during migratory phases, unthriftiness in young animals with heavy infections

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15
Q

Parascaris equorum-Diagnosis

A

Fecal flotation for eggs

Eggs may be absent with clinical signs

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16
Q

Parascaris equorum-Treatment and Prevention

A

Anthelmintics, timing of treatment

Resistance with some MCLs

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17
Q

Strongyloides westeri-Common Name

A

Threadworm

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18
Q

Strongyloides westeri-Hosts

A

Equine

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19
Q

Strongyloides westeri-Identification

A

Adults: slender hair-like nematodes, less than 1 cm long, long esophagus (1/3 of body)
Eggs: Thin-shelled, larvated, 30-40 um

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20
Q

Strongyloides westeri-Life Cycle

A

Direct. PPP = 10-14d
Parasitic (homogonic) and Free-living (heterogonic) phases
L3 infective stage
Per Os, Percutatneous, Transmammary

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21
Q

Strongyloides westeri-Site of Infection

A

Adults in small intestine

Larvae in somatic tissues

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22
Q

Strongyloides westeri-Pathogenesis and Lesions

A

Erythematous reaction from larval penetration of skin

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23
Q

Strongyloides westeri-Clinical Signs

A

Larvae cause urticaria, “frenzy”

Adults cause diarrhea (usually in young)

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24
Q

Strongyloides westeri-Diagnosis

A

Fecal flotation reveals eggs with L1
Baermann
expect to see parasite in <5mths old horses

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25
Strongyloides westeri-Treatment and Prevention
Incorporated with control of Strongyles and ascarids, normally not a critical parasite
26
Oxyuris equi-Common Name
Large Pinworm
27
Oxyuris equi-Hosts
Equine
28
Oxyuris equi-Identification
Adults: long white nematode with pointed tails reaching 10cm (4in) Eggs: 85 x 40um, single operculum, flatter on one side
29
Oxyuris equi-Life Cycle
Direct. PPP = 4-5mths Adults in dorsal colon→ gravid female migrates to anus to lay eggs around perineum→ eggs laid with gelatinous substance (irritant)→ larva devel. to L3 in egg Egg with L3 infective stage
30
Oxyuris equi-Site of Infection
Large Intestine
31
Oxyuris equi-Pathogenesis and Lesions
Pruritus
32
Oxyuris equi-Clinical Signs
Peri-anal irritation (from eggs and gelatinous substance)
33
Oxyuris equi-Diagnosis
Broken hair at tailhead Adhesive tape method Perianal scraping method
34
Oxyuris equi-Treatment and Prevention
Parasitides (MCLs, FBZ, etc.) | Resistance suspected
35
Strongylus spp.-Common Name
Large Strongyles | S. vulgaris, S. edentatus, S. equinis
36
Strongylus spp.-Hosts
Equine
37
Strongylus spp.-Identification
Adults: globular mouth capsule, S. vulgaris: 1-2cm, 2 dorsal ear-shaped teeth in mouth S. edentatus: 3-4cm, no teeth S. equinus: 3-4cm, one large tooth with a bifid tip and two smaller subventral teeth Eggs: all the same, 60-120 x 35-60um
38
Strongylus spp.-Life Cycle
Direct. PPP = 6mths L3 are infective stage L3 ingested while grazing→ migrate to cranial mesenteric and ileocolic a.a. molting along the way (S. vulgaris) / through liver and abdominal tissues (S. edentatus) / through liver (S. equinus)→ migrate back to large intestines→ adults
39
Strongylus spp.-Site of Infection
Larvae in arterial vessels of intestines (S. vulgaris), liver and abdominal tissues (S. edentatus) or liver (S. equinus) Adults: Large intestine
40
Strongylus spp.-Pathogenesis and Lesions
Larvae- Arteritis, marked thickening of arterial wall, thrombus, infarction, death, aberrent larval migration Adults- bloodsuckers, remove plugs of mucosa
41
Strongylus spp.-Clinical Signs
Larvae cause thrombo-embolus, colic | Adults cause anemia with heavy infection
42
Strongylus spp.-Diagnosis
Eggs in fecal--Cannot differentiate small from large strongyles L3 in culture Migrating larvae--ultrasound, rectal exam and palpation, arteriography Adults--necropsy
43
Strongylus spp.-Treatment and Prevention
Anthelmintics | No resistance
44
Cyathostominae-Common Name
Small strongyles or cyathostomins
45
Cyathostominae-Hosts
Equine
46
Cyathostominae-Identification
Adults: less than 15mm in length, mouth capsule not globular but rectangular or square Eggs: typical strongyle, 60-120 x 35-60um
47
Cyathostominae-Life Cycle
Direct. PPP = 6wks to 2-4 mths L3 infective form L3 ingested while grazing→ penetrate large intestinal wall→ emerge later as L4→ adults Arrested devel. up to 2.5 yrs.
48
Cyathostominae-Site of Infection
Larvae within cecum, ventral/dorsal colon | Adults in intestinal lumen (lg. intestine)
49
Cyathostominae-Pathogenesis and Lesions
Larval cyathostominosis lymphocytic and eosinophilic infiltration Catarrhal colitis Protein losing enteropathy
50
Cyathostominae-Clinical Signs
Affects younger horses Clinical signs associated with emergence of L4 Chronic diarrhea, colic, severe weight loss, edema, intussusception Seasonality
51
Cyathostominae-Diagnosis
Eggs in fecal exam | L3 in culture
52
Cyathostominae-Treatment and Prevention
Some BZs and MCLs for mucosal larval stages BZs, MCLs, and others for adults Resistance known to all drug classes Treat animals contaminating the pasture, clean up feces, mixed grazing, do not overstock
53
Dictyocaulus arnfieldi-Common Name
Lungworm
54
Dictyocaulus arnfieldi-Hosts
Donkeys | In horses, adults do not reach sexually maturity
55
Dictyocaulus arnfieldi-Identification
Adults: Long, slender, white nematodes, 8cm L1: 400um Eggs: 75um
56
Dictyocaulus arnfieldi-Life Cycle
Direct. PPP = 2-4mths Adults in bronchi lay eggs containing L1→ eggs hatch in lungs and in feces→ eggs and L1 found in feces→ devel. to L3→ migrate from feces to herbage→ L3 ingested
57
Dictyocaulus arnfieldi-Site of Infection
Bronchi
58
Dictyocaulus arnfieldi-Pathogenesis and Lesions
None in donkeys | Highly pathogenic in horses--damage to pulmonary tissues
59
Dictyocaulus arnfieldi-Clinical Signs
No clinical signs in donkeys | Horses: chronic, productive cough
60
Dictyocaulus arnfieldi-Diagnosis
L1 in eggs recovered from feces and lung washings with Baermann Adults in lungs at necropsy
61
Dictyocaulus arnfieldi-Treatment and Prevention
In endemic areas do not pasture donkeys and horses together
62
Setaria equina-Hosts
Equine | IH: mosquitoes
63
Setaria equina-Identification
Superfamily: Filarioidea Adults: long slender worms, 12cm
64
Setaria equina-Diagnosis
Mff in blood smears | Adults in peritoneal cavity
65
Onchocerca cervicalis-Hosts
Equine | IH: Culicoides spp.
66
Onchocerca cervicalis-Identification
Adults: slender nematodes b/w 2-6cm and lie tightly coiled in tissue nodules
67
Onchocerca cervicalis-Diagnosis
Mff in tissue spaces of the skin→recovered in saline incubation of skin biopsies Fistulous withers-open purulent lesions

Parasitology (16 decks)

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