Equine Parasites & Parasite-Associated Disease Flashcards
(80 cards)
1
Q
what are the nematodes in horses (5)
A
- parascaris equorum
- small and large strongyles
- strongyloides westeri
- oxyuris equi
- dictyocaulus arnfieldi
2
Q
what are the cestodes
A
- anoplocephala perfoliata
3
Q
what are the arthopods
A
gastrerophilus
4
Q
what is the lifecycle of nematodes
A
- adult parasites produce eggs or L1 in host
- eggs hatch L1 and
- moult to L2
- L3
- L4 ingested
5
Q
which is the largest nematode
A
parascaris equorum
6
Q
where do parascaris equorum reside in
A
small intestine
7
Q
what age do parascaris equorum affect
A
foals, weanlings and yearlings
adults develop acquired immunity
8
Q
how is parascaris equorum diagnosed
A
distinctive eggs in feces
9
Q
what is the prepatent period of parascaris equorum
A
10 weeks
10
Q
what is the parascaris equorum lifecycle (4)
A
- egg + L3 ingested
- hatching of L3 in the stomach and small intestine, penetration of intestinal veins
- larvae reach liver via portal vein, migration through liver tissue and penetration of liver veins
- larvae reach lung via vena cava and right heart, penetration into lung alveoles and migration via trachea and pharynx to small intestine (moulting to L4 and St5 prior to development into adults
11
Q
what is the disease parascaris equorum in foal and weanlings
A
larvae can cause tissue damage during migration –> mirgrate through liver (areas of fibrosis)
2-4 weeks after infection migrate through lungs and cause cough
12
Q
what disease does parascaris equorum cause in adult horses
A
cause ill thrift –> don’t attch to mucosa but compete for nutrients
can cause colic by luminal obstruction –> ascarid impaction, especially post deworming
13
Q
how is parascaris equorum controlled (3)
A
- avoid using same paddocks for nursing mares and foals in successive years
- resistence to fenbendazole, ivermectin and pyrantel –> fenbendazole less resistance in UK vs ivermectin
- deworm from 1 month of age, treat every 4 weeks, until 6mo old
14
Q
how is parascaris equorum treated (4)
A
- low bulk diet
- NGT with liquid paraffin (lubricate)
- treat with fenbendazole
- repeat FWEC 3 weeks after last dose
15
Q
which has a faster mode of action between ivermectin, pyrantel and fenbendazole in killing parascaris equorum
A
ivermectin and pyrantel cause quicker worm death than fenbendazole
16
Q
what is the dosing schedule in treating with fenbendazole in foals and weanlings
A
day 1: 2.5 mg/kg
day 4: 2.5 mg/kg
day 7-11: 10 mg/kg once daily for 5 days
17
Q
what are the large strongyles (3)
A
- strongylus vulgaris
- strongylus edentatus
- strongylus equinus
18
Q
where do adult strongylus vulgaris reside
A
in cecum and ventral colon attached to mucosa
19
Q
how is strongylus vulgaris infection diagnosed
A
eggs easily detected in feces
20
Q
what is the PPP of strongylus vulgaris
A
6-7 months
21
Q
what anthelmintics are strongylus vulgaris sensitive to
A
macrocyclic lactone
22
Q
what disease does strongylus vulgaris cause
A
associated with colic
23
Q
what is the life cycle of strongylus vulgaris (10)
A
- parasitic phase: L3 taken up orally with grass, exsheathment in small intestine
- penetration into wall of large intestine
- moulting to L4
- migration on or in intima of arteries of large intestine
- migration to cranial mesenteric artery
- moulting to pre adult stage
- migration to intestine and peentration of intestinal wall to enter lumen where development to adults is complete
- free living phase: thin shelled eggs expelled with feces
- development to L1 within the egg
- moulting to L2
- infective stage L3
24
Q
how do s. vulgaris develop in the horse
A
- L3 penetrate the intestinal wall and moult to L4
- migration of L4 into the cranial mesenteric artery
- moulting to St5 from 90th day post ingestion
- backwards migration from arteries to the gut
25
how does strongylus vulgaris cause disease
migration through mesenteric artieries leads to thrombosis, infarctions and necrosis of the intestine
non-strangulating infarction
surgical colic
26
how is strongylus vulgaris controlled
sensitive to anthelmintics
but possible increased prevelance due to selective deworming strategies
27
what are the small strongyles
cyathostomins
28
where do cyathostomins reside
cecum and large colon
29
what is the appearance of cyathostomins worms
\<1.5cm long white to dark red
30
what do cyathostomins invade
mucosal lining
31
what do cyathostomins form once they invade the mucosal lining
encysted larvae
32
what is the life cycle of cyathostomins (7)
1. eggs shed into feces --\> L1, L2, L3
2. oral uptake of L3
3. exsheathment through gastric fluids
4. passage of exsheathed L3 through small intestine
5. invasion of mucosa/submucosa of colon and cecum
6. moult to L4
7. return to intestinal lumen and final moult before development to adult stage
33
where do the L3 of cyathostomins reside
ileum and travel to the cecum
34
where do L4 of cyathostomins reside
develop from L3 in the cecum and travel to the ventral colon
35
what disease do larval cyathostomins cause
sudden onset diarrhea in late winter/spring
synchronous emergence of L4 from mucosa (potentially large #s)
life threatening colitis/diarrhea
36
at what age is colitis/diarrhea especially common from cyathostomins
\< 5 years old
37
how is cyathostomins disease treated (4)
1. replace lost fluid and protein (enteral or IV fluids, plasma transfusion/synthetic colloids)
2. anti-inflamamtories (corticosteroids?)
3. deworming (moxidectin vs fenbendazole)
4. supportive care and nursing
38
how is cyathostomins controlled (2)
1. encysted larval burden NOT detected by FWEC
2. limited # of anthelmintics active against encysted larvae (treat in winter) --\> moxidectin or fenbendazole (wide spread resistance)
39
what does strongyloides westeri affect
sucking foals
40
what is the PPP of strongyloides westeri
8-14 days
41
how is strongyloides westeri transmitted
arrested larvae in dam abdominal wall mobilized and excreted in milk
foals infected immediately after birth
42
what does strongyloides westeri cause
diarrhea in foals
43
how is strongyloides westeri controlled
deworm dam
1. moxidectin 4 weeks before parturition
2. ivermectin around time of foaling
44
what is the life cycle of strongyloides westeri
1. ingestion of food
2. free living L3 embed in ventral tissues of mare then called parasitic L3 which pass in milk to foal
3. parasitic L3 develop to adults in foals
4. two molts: L3 to L4 to L5
5. adult females in small intestine of foal
6. embryonated eggs (L1 inside) pass in foals feces
7. L1 hatch
45
what is oxyuris equi also called
pinworm
46
where do adult worms of oxyuris equi reside
in lumen of colon
47
where do oxyuris equi migrate to
gravid female mirgrates to anus, extrude anterior and lays her eggs in clumps
48
what is the PPP of oxyuris equi
5 months
49
what do oxyuris equi cause
irritation in perianal area --\> tail rubbing
50
how is oxyuris equi diagnosed
tape strip
51
how is oxyuris equi controlled
difficult
scrub environment
washing perianal area can reduce itch
fenbendazole for 5 days or pyrantel
52
what are dictyocaulus arnfieldi
lungworms
53
what disease does dictyocaulus arnfieldi cause
patent infection in donkeys that rarely produce clinical signs
horses develop severe bronchial inflammatory response
54
how are horses infected with dictyocaulus arnfieldi
by co grazing with donkeys
55
how is dictyocaulus arnfieldi diagnosed
difiicult to diagnose
56
what are cestodes
tapeworms
57
what is the basic lifecycle of cestodes (tapeworms) (7)
1. cysts ingested by final host
2. adults in S.I
3. gravid segments shed from worm and pass out in feces
4. contain eggs which are resistent
5. ingested by intermediate host
6. embryo released from egg in IMH
7. larva settles down and encysts
58
what is the most common cestode
anoplocephala perfoliata
59
where do anoplocephala perfoliata reside
in cecum
particularly adjacent to ileo-cecal junction
60
what is the intermediate host of anoplocephala perfoliata
forage mites (orbiatidae)
61
how is anoplocephala perfoliata diagnosed
eggs difficult to detect in feces
serum/saliva ELISA more sensitive
62
what disease is anoplocephala perfoliata assocaited with
colic
63
what is the life cycle of anoplocephala perfoliata (6)
1. gravid proglotids filled with eggs are expelled with the feces
2. eggs are released and taken up by box mites as IMH
3. infective cysticercoids develop in IMH
4. following oral uptake of infected mite with grass
5. cystercircoids are released during digestion of the mite
6. larvae attatch to intestinal mucosa and develop into adults
64
what type of colic does anoplocephala perfoliata cause (3)
1. spasmodic colic
2. ileal impactions
3. intussusception of cecum and colon
65
how is anoplocephala perfoliata controlled (3)
1. forage mites are widespread
2. FWEC not helpful --\> ELSA?
3. pyrantel/praziquantel in spring and autumn, twice yearly if high ELISA, once yearly if low
66
what are trematodes
fasciola hepatica
but rare in horses
may cause liver disease
67
what are gasterophilus species (4)
1. G. intestinalis: cardia of stomach
2. G. nasalis: pylorus/duodenum
3. G. hemorrhoidalis: rectum
4. G. pecorum
68
what are gasterophilus
athropod: bot files gast
69
what are gasterophilus intestinalis transmitted
eggs laid on legs and hatch on contact with lips (grooming)
70
what diesease does gasterophilus intestinalis cause
not generally associated with disease just irritation from flies laying eggs
71
what is the disease that gasterophilus hemorrhoidalis/nasalis cause
attached to rectal mucosa and can cause rectal prolapse
72
summarize the intestinal parasites and where they reside
73
what parasite(s) resides in the cecum/ileocecal valves
a. perfoliata (tapeworm)
74
what parasite(s) resides in the small colon/rectum
o. equi
75
what parasite(s) resides in the stomach
G. intestinalis (bots)
76
what parasite(s) resides in the small intestine
1. P. equorum - young hroses
2. S. westeri - foals
77
what parasite(s) resides in the cecum/large colon
1. large strongyles
2. cyathostomins (small strongyles)
78
what should parasite control strategy combine (3)
1. chemical (anthelmintic dosing)
2. non-chemical (pasture hygeine)
3. all horses from grazing group should share same regimen
79
how can pasture management reduce parasites
1. regular removal of manure
2. rotation grazing or mixed grazing with ruminants
3. avoid high stocking density/young horses
80
how should deworming be done
based on FWEC of all animals 3-4x per year in grazing season
anthelmintic treatment for positive horses (\>200 epg)
