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Horse Systems and Management > Endoparasites > Flashcards

Endoparasites Flashcards

1
Q

what is a parasite?

A

an organism that lives off of another organism at the expense of its host

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2
Q

what are endoparasites?

A

small organisms that live a portion of their life cycle inside a host animal

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3
Q

where do endoparasites live when inside an animal (3)? how do they gain nutrients?

A
  1. body cavities
  2. internal organs
  3. tissues
    gain nutrients by feeding off the host animal
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4
Q

why are few horses free of internal parasites?

A

they are natural grazers, so they pick up parasites from the ground and from feces on the ground

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5
Q

what is the goal with parasite management in horses?

A

to keep numbers low; pronanly can’t eradicate completely bc grazers

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6
Q

what are the negative results of a parasite infestation in a horse? (2)

A
  1. loss of nutrients and blood from the host resulting in severe problems and death if not controlled
  2. serious economic and physiological problems
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7
Q

what are 8 symptoms of parasitism in horses?

A
  1. weakness (even with small load)
  2. unthriftyness (even with small load)
  3. emaciation (larger load)
  4. potbelly: large, distended abdomen
  5. tucked up flanks (narrow in lumbar vertebrae area)
  6. rough hair coat
  7. slow growth
  8. performance dwindles as horse is lethargic
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8
Q

what is acute parasitism?

A

when a lot of eggs hatch all at once, usually in a particular area of the body

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9
Q

what are 4 signs of acute parasitism? relate to where the hatch or migrations occurs

A
  1. colic (intestine)
  2. diarrhea (intestine)
  3. cough (lungs)
  4. lameness (circulatory system)
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10
Q

where can migration of parasits cause injury to? (5)

A
  1. lungs
  2. liver
  3. blood vessels
  4. intestines
  5. other body organs
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11
Q

what are strongyles? what are the two types?

A

blood worms; large and smal

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12
Q

what are the 4 major endoparasites?

A
  1. large strongyles
  2. small strongyles
  3. tapeworms
  4. roundworms
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13
Q

of the 4 major types of endoparasites, which on causes the most damage in horses?

A

large stongyles; or strongylus vulgaris

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14
Q

is the large strongyle, strongylus vulgaris, still the most important endoparasite?

A

no; it used to be because it is the most common and due to the types of damage cuased by its immature stages, but now we have more effective dewormers against it, so others are actually more problematic

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15
Q

what are the 3 kinds of large strongyles? which does the most damage?

A
  1. strongylus vulgaris (most damage)
  2. strongylus edentatus
  3. strongylus equinis
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16
Q

how many species of small strongyles are there? what is their collective name?

A

over 40 species of small stronglyes, collectively referred to as cyathostomes

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17
Q

describe the life cycle of strongylus vulgaris

A

direct (no intermediate host in development)

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18
Q

where are stronglye larvae found? how hardy are they?

A

on vegetation and surroundings; very resistant to adverse weather conditions and eclosed in a sheath so super hardy and may survive winter or drought

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19
Q

what happens to strongyle larvae under favorable conditions? (2)

A
  1. become active
  2. migrate up and down blades of grass in pastures
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20
Q

when is the infection stage of strongyles swallowed (3) also give two other places these can be picked up by horses

A
  1. when horse grazes or
  2. eats off the ground or
  3. drinks water from a contaminated sources
    can also be picked up if a horse licks stall walls or mangers
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21
Q

what happens once strongyles are ingested? (2)

A
  1. they lose their sheath
  2. then enter the wall of the terminal protion on the small intestine, cecum, and large intestine and form cysts/capsules
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22
Q

following a short period of encapsulation, what do strongylus vulgaris do?

A

larvae burrow into small artery walls and migrate to the anterior mesenteric artery, which is the main supply of blood to small and large intestines

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23
Q

what does the migration of strongylus vulgaris larvae to the mesenteric artery cause? (3)

A
  1. disruption of blood flow
  2. formation of blood clots in the artery
  3. irritation to artery walls, causing them to thicken and reducing the amount of blood flowing to the small intestine, colon, and cecum
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24
Q

what happens as the mesenteric artery becomes more restricted due to migration of strongylus vulgaris larvae? (2)

A
  1. blood pressure causes the wall to balloon out
  2. thrombi in the vessel are released and lodge within the arteries of the intestine, heart, kidney, liver, and legs (are called embolisms while mobile; when go to legs can cause lameness)
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25
Q

how long do strongylus vulgaris larvae remain in the anterior mesenteric artery and why?

A

about 120 days (4 months) while they grow

26
Q

what happens once strongylus vulgaris larvae in the anterior mesenteric artery are fully grown?

A

the begin a migration down the arteries to the lumen of the large intestines to finish maturation and begin to lay several thousand eggs each day

27
Q

what do adult large strongyles do?

A

attach to the mucose of the cecum and large colon and suck blooad, causing inflammation and small bleeding ulcers in the intestinal lining

28
Q

what happens to the eggs laid by adult large strongyles?

A

they are passed in manure and the life cycle starts again

29
Q

how long is the entire life cycle of a large strongyle?

A

6-7 months

30
Q

compare the other two large strongyles (edentatus and equinis) to vulgaris (4)

A
  1. similar life cycles
  2. migratory pathways not as destructive
  3. migrate to and through the liver, causing damage and then return to the large intestine
  4. life cycle take 8-11 months
31
Q

how long is the life cycle of small strongyles?

A

about 8 weeks

32
Q

what 7 symptoms are observed in horses acutely affected with strongyles?

A
  1. fever
  2. poor appetite
  3. rapid weight loss
  4. depression
  5. lethargy
  6. abdominal distress (colic)
  7. possibly death
33
Q

other than the classic symptoms, what MAY occur in horses acutely affected with strongyles? (2)

A
  1. may have episodes of diarrhea and intermittent bouts of constipation
  2. may have phlebitis (inflammation of vein)
34
Q

what may appear with exercise in horses acutely affected with strongyles?

A

lameness from emobli in legs

35
Q

describe the general body condition of horses acutely affected with stronglyes (3)

A
  1. unthrifty
  2. dull or roughened hair coat (due to nutrients rerouting to affected vital organs)
  3. impaired performance even with adequate nutrition
36
Q

what is the fancy name for roundworms?

37
Q

give an ascarid (roundworm) that affects horses

A

parascaris equorum

38
Q

describe parascaris equorum

A

very large (females up to 15in long) yellowish-white worms

39
Q

where are parascaris equorum passed?

A

may be passed in the manure of young foals and horses

40
Q

what kind of horses are pirmarily affected by parascaris equorum? give general and then two

A

young horses:
1. sucklings and weanlings
2. less than 2 years old

41
Q

can you deworm foals?

A

yes,but not with super harsh chemical

42
Q

what may horses develop in response to parascaris equorum?

43
Q

what kind of life cycle does parascaris equorum have?

44
Q

how long is the parascaris equorum life cycle from egg to egg-producing adult?

A

10-12 weeks

45
Q

how are infected eggs (containing larvae) swallowed by horses? (5)

A
  1. by eating infested grass
  2. through feed
  3. through water
  4. licking stall walls
  5. licking udders
46
Q

what happens once parascaris equorum eggs are swallowed?

A

eggs hatch and larvae burrow into the wall of the small intestine where they migrate into veins

47
Q

once in the veins, what happens to parascaris equorum larvae?

A

they are carried to the liver by the portal vein, where they remain for 1 week

48
Q

after living in the liver for one week, what happens to parascaris equorum larvae?

A

they travel to the lungs, where they move to alveoli, and are coughed up and then swallowed, allowing them to return to the small intestine to mature in the duodenum

49
Q

what happens to the eggs laid by adult parascaris equorum?

A

pass into the feces, where they can develop into infective stage in 2 weeks in a favorable environment, or survive for a while since the eggs are hardy

50
Q

when does the damage caused by parascaris equorum begin? what does it cause?

A

during migration, which causes:
1. physical damage
2. inflammation
3. scarring of the liver and lung tissue

51
Q

what is the worst danger from a parascaris equorum infection?

A

perotonitis, or rupture of the small intestine

52
Q

what does a large number of parascaris equorum eggs cause in the gut?

A

decreased gut motility, which may trigger intussusception, which is where one part of the intestine slides back into another part, decreasing surface area

53
Q

what do parascaris equorum most commonly interfere with? (2)

A
  1. proper digestion
  2. absorption of feed
54
Q

what can large numbers of parascaris equorum cause?

A

blockage, or colic

55
Q

when do eggs start appearing in foal manure?

A

in foals 10-13 weeks old

56
Q

how many eggs can a female parascaris equorum worm lay per day? how many eggs may an infected foal pass per day?

A

female worm: up to 200,000 eggs per day
infected foal: can pass 50 million eggs/day

57
Q

describe the hardiness of parascaris equorum eggs

A

very resistant to adverse conditions; may remain infective for years in pastures and stalls

58
Q

can parascaris equorum infection be passed from one foal crop to the next? why or why not?

A

yes; due to lingering eggs

59
Q

what are 5 clinical signs of a parascaris equorum infection?

A
  1. unthriftiness
  2. pot belly
  3. rough hair coat
  4. slow growth
  5. depression
60
Q

what do some foals develop when infected with parascaris equorum?

A

some foals develop a cough and nasal discharge that can be mistaken for a respiratory infection, but will not respond to antibiotics

61
Q

how is a parascaris equorum infection diagnosed? what is a drawback of this diagnostic method?

A

microscopic fecal exam; use egg count to determine deworming frequency; drawback is that a horse may not be passing eggs when sampled

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