Endoparasites pt. 2

Question 1

give an example of a threadworm species and describe

Answer 1

strongyloide westeri; hair like parasites 8-9 mm (1/3 inch)

Question 2

in what animals are stongyloides westeri most common?

Answer 2

foals 4-47 days old (up to 4 months old)

Question 3

how do foals pick up strongyloides westeri? (2)

Answer 3

1. ingest from dam udder (larvae in the milk)
2. ingest from ground

Question 4

how do mares pick up strongyloides westeri?

Answer 4

when grazing, they penetrate the mare’s tissue

Question 5

can strongyloides westeri pass from one foal crop to another?

Answer 5

yes, somatic larvae can persis in the body tissue of a mare for years

Question 6

in terms of strongyloides westeri, what kind of threat do mares pose to foals?

Answer 6

they serve as a persistent, perennial source for contamination to each foal crop as long as conditions are not too harsh

Question 7

do mares carry open strongyloides infections that shed eggs?

Answer 7

nope; they just act as reservoirs

Question 8

how do mares pass on strongyloides westeri infections? (2)

Answer 8

1. can shed eggs in manure and pick up again while grazing
2. when lactating, larvae migrate to the udder and foals can pick them up

Question 9

what do ingested strongyloides westeri larvae stimulate in suckling foals? when does self cure begin and what can you do until then?

Answer 9

stimulate and immune response; self cure begins around 6 months of age but can manage infections with deworming until then

Question 10

what do the strongyloides westeri eggs shed by foals contain?

Answer 10

infective stage larvae under favorable environmental conditions

Question 11

what are favorable environmental conditions for strongyloides westeri larvae?

Answer 11

warm and damp

Question 12

once ingested, or inside the horse, where do strongyloides westeri larvae go? what is their final destination and what do they do when they get there?

Answer 12

migrate to the lungs, up the trachea, and then are swallowed to reach the small intestine, where they will continue to mature until the female starts laying eggs

Question 13

how long is the strongyloides westeri life cycle?

Answer 13

2 weeks

Question 14

what are the most common clinical signs of a strongyloides westeri infection in foals? (4)

Answer 14

diarrhea is most common, and then leads to weight loss, poor appetite, and dehydration

Question 15

how is a strongyloides westeri infection diagnosed? is this a reliable method?

Answer 15

diagnosed with fecal float, but not always reliable because foal might not be shedding at time of sample collection

Question 16

are stomach bots worms? if not what are they?

Answer 16

not worms, they are the larvae of the botfly Gasterophilus

Question 17

where is the larval stage of gasterophilus found?

Answer 17

in the horse stomach

Question 18

where/how do female gasterophilus botflies lay their eggs?

Answer 18

lay eggs by attaching them to the hairs of the horse, on the LEGS (mainly found), chest, barrel, and lip area

Question 19

what stimulates the botfly eggs on the legs and other areas of horses to hatch?

Answer 19

lip action and warm salive as the horse licks itself

Question 20

as the horse licks at the hatching eggs of botflies, what happens next?

Answer 20

larvae attach and burrow into the tongue and gums of the mouth

Question 21

where do botfly larvae incubate and for how long?

Answer 21

incubate in the tongue and gums of the mouth for 3-4 weeks for growth and development

Question 22

what happens after botfly larvae incubate in the tongue and gums of horses?

Answer 22

they are swallowed and attach to the lining of the stomach

Question 23

how long do botfly larvae spend attached to the stomach lining of a horse? what happens after this period?

Answer 23

spend 9-10 months attached to the stomach lining before passing out with manure

Question 24

what is caused by the attachment of botfly larvae to the stomach lining of horses? give general and then 4 specific

Answer 24

damage to stomach:
1. weakening of stomach lining
2. ulcers
3. abdominal distress and digestive disturbances
4. peritonitis if complete penetration

Question 25

what is the margoplicatus? how does it relate to botflies?

Answer 25

it is the demarcation between the glandular and nonglandular stomach, and sometimes botfly larvae like to hang out along this line when attached to the stomach lining

Question 26

what can happen as a result of botflies in the stomach lining relating to food?

Answer 26

can obstruct feed passage from stomach to the small intestine

Question 27

what happens after botfly larvae pass out in manure?

Answer 27

they spend about 3 weeks burrowed in manure or soil as larvae pupate into adult flies

Question 28

what does the length of the botfly life cycle depend on?

Answer 28

whether the parasite larvae are over-wintering in the stomach, and then passing out in the spring before developing into adult flies

Question 29

when are adult bot flies active?

Answer 29

from late spring to killing frost in the fall (May to October)

Question 30

when should you deworm against botflies?

Answer 30

when they are active: late spring to late fall

Question 31

how many generations of botflies are completed per year?

Answer 31

just one

Question 32

describe the life cycle of bot flies (3)

Answer 32

1. indirect 2. intermediate step outside of the host is required before reaching maturity (pregnant female depositing the eggs on the hair of the legs, chest, lips) 3. horse must ingest the botfly larvae somehow to continue the cycle

Question 33

what are 2 clinical signs of an outward/botfly egg infection?

Answer 33

1. yellowish egg cases attached to the horse in the summer and fall 2. may be sores/ulcers in the mouth that can impair feed intake

Question 34

what is the fancy name for tapeworms?

Answer 34

anoplocephala

Question 35

in what age horse are tapeworms found?

Answer 35

all ages

Question 36

how many types of tapeworms are there? which is most common in horse?

Answer 36

at least 3 types; anoplocephala perfoliata is most common in horses

Question 37

describe anoplocephala perfoliata tapeworms

Answer 37

pumpkin seed shaped with 4 suckers attached to the intestinal lining at the ileocecal junction

Question 38

how are tapeworm eggs passed? what are they then ingested by?

Answer 38

passed in manure; ingested by oribatid mites

Question 39

what is the intermediate host in the tapeworm life cycle?

Answer 39

oribatid mites

Question 40

describe oribatid mites (2)

Answer 40

1. ingest tapeworm eggs 2. serve as hosts to developing tapeworms until cysticercoids mature in 2-4 months

Question 41

how do horses pick up tapeworm-infected oribatid mites?

Answer 41

eat them while grazing

Question 42

what happens once tapeworm-infected oribatid mites are ingested while horses are grazing?

Answer 42

the larvae travel to the ileum, then attach at the ileocecal junction

Question 43

after traveling to the ileocecal junction, how long do tapeworm larave take to mature?

Answer 43

reach maturity in 6-10 weeks

Question 44

where are populations of oribatid mites found? where are they more common?

Answer 44

the mites are found in low-lying, wet pastures and are more common in areas that have been overgrazed

Question 45

what increases the potential for tapeworm transmission via oribatid mites?

Answer 45

wet weather and overgrazing

Question 46

other than a fecal float, what are 2 other methods for diagnosing tapeworms?

Answer 46

1. blood test for specific tapeworm protein antibodies 2. a saliva-based ELISA, which came out in 2016 and is used in the UK

Question 47

where are the highest levels of infestation/what horse populations are most susceptible to tapeworms? (2) why?

Answer 47

1. young horses between 6 months and 2 years old 2. horses older than 15 years; because these horses spend more time on pastures and have weaker immune systems

Question 48

what are small strongyles called? how many species are there? where are they found? do they migrate?

Answer 48

cyathostomes; over 40 species; reside in the intestines with no migratory path

Question 49

what is tricky about small strongyles and why is this?

Answer 49

they are difficult for the immune system to defend due to their encapsulation

Question 50

how do small strongyle larvae get into the horse?

Answer 50

the laarvae are swallowed from vegetation or grass

Question 51

what happens after small strongyles are ingested? (3)

Answer 51

1. they invade the mucose of the large intestine 2. then a tough capsule of scar tissue forms 3. these cysts protect larvae from immune system and most dewormers until a good time comes for them to emerge and continue their life cycle

Question 52

how long can small strongyles remain encysted? what does length of time depend on?

Answer 52

for years; depends on the environment and also how many other small strongyles are already present; if too many, may not encyst because not enough room

Question 53

when do small strongyle cysts typically emerge?

Answer 53

in the spring, can tell it's spring bc horse temp and diet change

Question 54

what do encysted small strongyles do? where are they mainly located?

Answer 54

enter a period of dormancy where they continue to develop, mainly in the large colon

Question 55

what will eventually happen to all small strongyles and where?

Answer 55

they will all eventually morph into adults in the lumen of the GI tract

Question 56

how many eggs can be produced in a horse per day by an entire small strongyle population? what is this due to?

Answer 56

can produce over several million eggs/day; due to synchronous emergence from many cysts

Question 57

what symptoms are caused by a population of small strongyles in a horse, generally/encysted state? (4)

Answer 57

1. irritate intestinal tissue 2. diarrhea 3. weight loss 4. anemia

Question 58

what is larval cyathostominosis? what symptoms can it cause? (5)

Answer 58

synchronous emergence of many small strongyle larvae 1. sudden onset diarrhea 2. impaired gut motility 3. weakness 4. muscle wasting 5. serious colic

Question 59

what is a fancy name for dewormers?

Answer 59

antihelmintics

Question 60

what are the 4 major classes of antihelmintics?

Answer 60

1. benzimidazoles 2. macrocylic lactones 3. tetrahydropurimidines 4. isoquinolines

Question 61

what aare the 2 ways in which antihelmintics must work?

Answer 61

either by 1. interfering with energy/nutrient metabolism 2. or nervous system of parasite

Question 62

what is one type of benzimidazole? give two brands

Answer 62

fenbendazole 1. panacur 2. safe-guard

Question 63

what are two types of macrocyclic lactones? give an example of each

Answer 63

1. avermectins: ivermectin 2. melbemycins: moxidectin (Quest)

Question 64

what is a type of tetrahydropurimidine? give an example

Answer 64

pyrantel pamoate; strongid

Question 65

what is a type of isoquinoline? give an example

Answer 65

praziquantel; zimecterin gold

Question 66

how do you deworm tapeworms? (2 methods)

Answer 66

1. double dose of pyrantel (Strongid) or 2. praziquantel

Question 67

how do you deworm bots? (2)

Answer 67

1. ivermectin or 2. moxidectin

Question 68

how do you deworm encysted small strongyles? (2)

Answer 68

1. moxidectin or 2. a 5 day panacur powerpack

Question 69

how often should you deworm your horse?

Answer 69

depends on the horse and the parasite load; use fecal egg count to determine highest shedders if you can