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Equine biology > Parasites > Flashcards

Flashcards in Parasites Deck (25):
1

4 main parasites of intestines

-anoplocephala paranoplocephala, strongylus vulgaris, small strongyles, parascaris equorum

2

how parasites damage hosts

-competition for nutrients
-sucking blood
-tissue destruction
-physical obstruction
-immune mediated reactions
-abnormal migration patterns

3

degree of harm depends on...

pathogenic potential of parasite
-concentration of parasites
-immune status of host
-general health of host

4

cyathostomins or small strongyles

one of most common parasites
pre-patent period 2-3 months inside host, eggs come out in feces and ingested by horses
-can infect host after one week in ideal conditions
-mild unless have large numbers
-larvae undergo inhibited development in gut mucosa, remain as third stage larva until spring
-need access to pasture, cause GI disturbance

5

clinical signs of cyathostomins

diarrhea, dehydration, inappetance, wasting, edema, sometimes death

6

anoplocephala perfoliata tapeworm

pre-patent period 1-2 months
-immediately infective eggs; develop in host in 2-4 months
-can cause infection colic
-indirect lifecycle, infection occurs in infected mites
-needs pasture
-egg counting difficult due to egg shedding

7

parascaris equorum

worldwide distribution
-major pathogen in FOALS AND YEARLINGS
-pre-patent period of 10 weeks
-infective in 3 weeks
-infective in confiement and pasture
-deworming can cause acute small intestinal impaction
-can cause poor growth, airway inflammation, cough, and nasal discharge

8

parasite control aims to

-minimize risk of parasitic disease
-control parasite egg shedding
-maintain effective drugs and avoid resistance development
ultimate goal is to LIMIT parasite infections to keep animals healthy, not to eliminate parasites from individual

9

factors of horse to consider

-susceptibility to infection differs between individuals
-horses <3years are more susceptible
-increasing antihelmintic resistance
-refugia, ability to survive and stay in host, important

10

differing susceptibility

ie small strongyles
-20-30% of adult horses shed 80% of eggs, 90% are small strongyles

11

antihelmintic resistance

-ability for parasite to survive treatments
-resistance is inherited
-once resistant the population cannot lose it, resulting in more resistant parasites

12

refugia

portion of population that avoid treatment due to being larvae, encysted stages, free-living parasites on pasture, or simply weren't treated
-they DILUTE the population of resistant worms

13

preventing resistance

-prevent resistance from developing and reduce accumulation of resistant genes
-fecal egg count reduction test FECRT is only method used for detecting resistance
-fecal egg counts FEC also used for checking parasite loads on horses

14

drugs used

fenbendazole "panacur"
pyrantel "strongid"
ivermectin "eqvalan"
moxidectin "quest"
praziquantel (mix of the others)

15

do drugs kill larval stages? why is this a problem?

NO; and larval stages can cause most of the disease
-can prevent this by killing worms before pass large number of eggs into the environmen
-only necessary in spring or summer, where conditions are good for egg development

16

use praziquantel for...

anoplocehala

17

for parascaris larva use...

ivermectin and moxidectin

18

which parasite has no evidence of resistance in NA

large strongyles

19

tools for effective deworming

-fecal egg counts
-fecal egg count reduction test

20

fecal egg count

-measure amount of eggs of parasite in horse manure
-determine as low or high shedders
-used to evaluate deworming program effecacy
-target drug to parasite, esp in foals

21

limitations of FEC

-cannot tell the species, or large or small strongyles
-not accurate reflection of some parasites
-does not detect immature or larval stages including migrating large strongyles
-tapeworm egg shedding inaccurately detected
-pinworms rarely shed in feces

22

FECRT

-used to determine if strongyles or ascarids are resistant to given anthelmintic
steps: collect fecal sample prior to deworming
-administer anthelmintic
-collect fecal sample 14 days following
goal: 90-98% reduction

23

deworming strategies for adults

-treat every horse 1-2 times
-all other treatments target high shedders of strongyles; higher frequency of FEC and treatment
-treat during times with peak transmission (spring and fall) and when refugia present
-treat tapeworms in late fall/winter
-evaluate efficacy of dewormers at minimum every 3 years

24

deworming for foals

DO NOT USE FEC
=focus on Parascarus, which cause poor growth, colic, airway inflammation and nasal discharge
-2-3 months fenbendazole, note: ivermectin note for foals
-6months/weaning=FEC
9 and 12 months=strongyles and tapeworms

25

strategies via environment

proper composting of feces
-pasture rotation
-remove feces from pasture