Internal Parasites Flashcards by Emily Cottenden

what age is most susceptible to parasites?
what are the most common parasites?

young horses are most susceptible

most common is roundworms(ascarids) and strongyles

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issues caused by high parasite load

anemia
diarrhea
weight loss
poor condition
general debility
permanently stunt growth in young horses

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2 groups of strongyles
which is more damaging?

large and small
large is more damaging

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where do large vs small strongyles stay in the body

large: migrate through circulation and damage blood vessels

small: stay in the wall of the gut

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what is the most harmful large strongyle

vulgaris

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3 species of large strongyles(smallest to largest)

vulgaris
endentes
equninus

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infection rate of large strongyles in adult horses

70-100%

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effects of s. vulgaris on arteries

causes damage that leads to thrombosis clotting and aneurisms

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what are aneurisms

-sack-like enlargement of the artery
-can rupture and cause internal bleeding
-can cause embolism(arteries blocked by clotting)

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how may thromboembolism be diagnosed

rectal palpation

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what is the main cause of colic and abdominal pain from strongyles

thrombosis and embolism

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at what age do S. vulgaris return to intestines and develop into adult worms

5 months

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pros and cons of strategic deworming

Pros: targets specific parasites based on fecal egg counts, decreases risk of parasites developing resistance

Cons: more labor intensive to take fecal egg counts

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pros and cons of routine deworming

Pros: less labor to determine specific parasites

cons: generally more expensive, more possibility of parasites becoming resistant

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where are S. edantus and S. equinus located in the body

-liver
-perineal tissue(between anus and scrotum/vulva)
-retroperitoneal tissue
-pancreas

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T/F edantus and equinus produce lesions inthe mesenteric arteries

FALSE

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what is the most common internal parasite in adult horses

small strongyles

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main locations in body preferred by small strongyles

cecum and colon

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what issues do small strongyles cause when they encyst(enclose in a cyst)

colic
bleeding
anemia
protein loss
intestinal malabsorption

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what time of year do larvae of small strongyles rapidly emerge from the gut wall

spring

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how long does it take for eggs of strongyles to appear in the feces after the start of infestation

9-12 months

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what type of dewormer works on S. vulgaris

avermectins

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what type of dewormer have small strongyles developed resistance to

benzimidazoles

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what is the most harmful species of ascarid? what age is it the biggest issue in

parascaris equorum

biggest issue in nursing and weanling foals

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how large can P. equorum get

up to 12 inches

path of ascarids after ingestion? how long does this process take?

larvae migrate through liver and into the lungs in the SI they mature into adult worms this process takes 10-12 weeks

adverse effects of ascarids

malnutrition stunted growth diarrhea cough and nasal discharge when in lungs

why do you not want to use a rapid acting dewormer on a horse with a heavy parasite load

rapidly killing parasites will lead to them building up in the intestines and causing colic

what is a good slow acting dewormer for the treatment of ascarids

oxibendazole

what species of ascarids doesnt develop resistance towards dewormers

P. equorum

general deworming schedule of newborn foals to prevent ascarids

start at 8 weeks continue every 2 months until one year of age

what is the major threadworm of concern

strongyloids westeri

how do foals acquire parasites

through dams milk or eating feces

what is the first intestinal parasite to mature in young foals? how quickly do they mature?

strongyloides westeri can mature in less than 2 weeks

what dewormers should be used to treat threadworms

oxibendazole or ivermectin

symptoms of threadworms in foals

worssened foal heat diarrhea

how to prevent threadworms in areas where they are a bigger problem

deworm foal at 3 weeks and deworm mare 12 hours after birth

three species of bot fly and where they deposit their eggs

G. nasalis-deposit beneath jaw and on throat G. hemorrhoidalis-deposit on shot hair of lips G. intestinalis- deposits on chest, shoulders, and forelegs

most common bot fly

gastrophilus intestinalis

life cycle of bot flys

enter as larvae and spend 10 months attached to wall of stomach. in spring they release and pass with manure. they burrow into the ground in pupal stage for 3-5 weeks and emerge as adults

signs of bots

-larval ulcerations in mouth -colic -ulcers -perforation of stomach lining

dewormers to treat bots

organophosphates or ivermectins

prevention of bots

-sponge arras bots lay eggs to reduce amount that enter the mouth -insectisides on areas bots lay their eggs

what type of horse are pinworms most common in

stabled horses

where do adult pinworms live? where does the female lay eggs

adults live in colon female lays eggs around anus or vulva

how can pinworm eggs be found

applying clear tape to perinium then examining the tape under a microscope

how to prevent/treat pinworms

-clean anal area with warm soapy water daily -use disposable towels to avoid transmitting eggs -anthelmintics are preventative

what parasite was believed to not be a big deal in horses for a long time

tapeworms

how many cases of spasmodic colic an ileocecal impactions were found in horses with tapeworms

spasmodic: 1/5 ileocecal: 3/4

percentage of horses with tapeworm in the midwest? what age of horses have higher rates of tapeworms

95% in midwest under 2 and above 15 have higher rates

how are tapeworms discovered

blood test to screen for antigen specific to tapeworm protein

theories to why middle aged horses have lower rates of tapeworm

-they have better immunity to tapeworms specific protein antigen -they may not be pastured as much due to their high performance

how do horses get tapeworms

eating infected mite while grazing

what do tapeworm eggs look like

kernels of rice capable of movement

how big can tapeworms get

up to 12 inches(though they rarely get that big)

tapeworm treatment

praziquantel with an avermectin(ivermectin or moxidectrin)

what are lungworm infestations related to

contact with burros or donkeys

how big can lungworms be? how quickly do eggs hatch?

can be 4 inches larvae hatch within hours

signs of lungworms

-persistent cough for months -labored breathing -loss of weight and appetite -wheezes

what non parasite issue has symptoms similar to lungworms and is more common

recurrent airway obstruction

what are habronema

stomach worms that live in colonies of the wall of the stomach

how does habronema invade

feed on wounds or around eyes or male genetalia

symptoms of stomach worms

generally asymptomatic, severe cases can cause gastritis(inflammation of stomach lining)

secondary effects of stomach worms

summer sores and conjunctivitis

treatment of stomach worms

fly control ivermectin