Equine Internal Parasites

What are the nematodes?

roundworm, strongyles, pinworm, threadworm, horse/stomach bot, stomach worm

What is the common name for Parascaris equorum?

Ascarid/roundworm

What are the nematodes?

roundworm, strongyles, pinworm, threadworm, horse/stomach bot, stomach worm

What is the common name for Parascaris equorum?

Ascarid/roundworm

What is the definitive host for Parascaris equorum?

horse and donkey

What is the intermediate host for Parascaris equorum?

none

Where do Parascaris equorum larvae migrate?

liver and lungs

Where do Parascaris equorum adults stay?

small intestine

What is the infective stage of Parascaris equorum?

2nd stage larva

Who is mostly affected by Parascaris equorum?

foals 2-6 months old, horses develop immunity by 6 months

What can Parascaris equorum cause?

obstruction or perforation of the intestine/bile duct

What are clinical signs of Parascaris equorum?

during migration: frequent coughing, grayish nasal discharge

heavy infections: poor coat, pot bellied, weight loss w good appetite

How is Parascaris equorum diagnosed?

centrifuge BEST, fecal float

What is the common name for strongylus spp.

large strongyles

What are the definitive host for Strongylus spp.?

equines

What are the intermediate host for Strongylus spp.?

none

Where can you find Strongylus spp. larvae?

mesentric artery

Where can you find adult Strongylus spp.?

cecum and large intestine

What are the species of Strongylus?

Strongylus vulgaris

Strongylus edentatus

Strongylus equinus

What is one of the most important parasites in the U.S?

Strongylus spp.

Who is most affected by Strongylus spp.?

young up to 2-3 and older, seriously affects development and performance

What is the infective stage of Strongylus spp.?

3rd stage larvae

What stage of Strongylus spp. causes the most significant damage?

larvae

What are clinical signs of Strongylus spp.?

failure to thrive, poor coat, anemia, colic

What are signs of colic?

rolling, stretching, pawing, excessive sweating, not eating, kicking stomach

How is Strongylus spp. diagnosed?

centrifuge, fecal float, necropsy

What is the common name for Cyathostomes?

small strongyles

Who is the definitive host for Cyathostomes?

equines

Who is the intermediate host for Cyathostomes?

none

What is the infection site for Cyathostomes?

cecum and large intestine

What larvae is unaffected by many anthelmintics?

Cyathostomes

What is the common name for Oxyuris equi?

pinworm

Who is the definitive host for Oxyuris equi?

equines

What is the intermediate host for Oxyuris equi?

none

Where do you find Oxyuris equi?

cecum/large intestine, eggs around rectum

What parasite does not migrate through tissues?

Oxyuris equi

What are signs of Oxyuris equi?

irritation, rat tail

How do you diagnose Oxyuris equi?

observing scratching, scotch tape collection

How can you identify Oxyuris equi egg?

mucosal plug

What is the common name for Strongyloides westeri?

threadworm

What is the definitive host for Strongyloides westeri?

horse and donkeys

What is the intermediate host of Strongyloides westeri?

none

Where do you find Strongyloides westeri larva?

skin and lungs

Where do you find adult Strongyloides westeri?

adult horses do not harbor, can only transfer through prenatal infection

small intestines in foals

What stage is parasitic in Strongyloides westeri?

FEMALES ONLY, L3 and L4

How can a horse be infected by Strongyloides westeri?

ingestion, trandermal, transmammary

What are clinical signs of Strongyloides westeri?

diarrhea in the 5-15th day of life. diarrhea is not respondent to treatment

How is Strongyloides westeri diagnosed?

mucosal scrapings, fecal float, FOALS ONLY

has zoonotic potential

How is Strongyloides westeri treated?

treat mares within 24 hours of foal birth

What is the common name for Gasterophilus intestinalis/nasalis?

horse/stomach bot

What is the definitive host for Gasterophilus intestinalis/nasalis?

equines

What is the intermediate host for Gasterophilus intestinalis/nasalis?

horse bot fly

Where do you find Gasterophilus intestinalis/nasalis larva?

stomach and stomach lining

How many generations do Gasterophilus intestinalis/nasalis have per year?

one

Where can Gasterophilus intestinalis/nasalis be laid?

intestinalis (shoulders and skin)

nasalis (around jaws and lips)

How long until Gasterophilus intestinalis/nasalis larva are passed in the feces?

8-10 months

What is the pathogenesis of Gasterophilus intestinalis/nasalis?

irritation, interference with digestion, obstruction to small intestine opening

What are clinical signs of Gasterophilus intestinalis/nasalis?

worry factor (flies annoy the horse)

How are Gasterophilus intestinalis/nasalis diagnosed?

yellow eggs, visualized bot fly, larvae in feces

How can Gasterophilus intestinalis/nasalis be treated?

remove eggs as soon as they are laid, ivermectin

How can Gasterophilus intestinalis/nasalis be prevented?

fly control, medication, keep horses stabled during the day, flies arent active at night

What is the common name for Habronema spp.?

stomach worm

What is the definitive host for Habronema spp.?

equine

What is the intermediate host for Habronema spp.?

house/stable flies

Where can you find Habronema spp. larvae?

cutaneous lesions “summer sores”

Where are adult Habronema spp. seen?

stomach

What stage of Habronema spp. parasitizes the skin?

larval NEVER adults

How do horses get Habronema spp. ?

ingesting infected flies in food or water, larvae can be deposited on wounds

How is Habronema spp. diagnosed?

rarely found in fecals, cutaneous infections gross exam/biopsy

How is Habronema spp. treated?

stomach infection: moxidectin, ivermectin

cutaneous infection: ivermectin, surgery

What is the common name for Anoplocephala perfoliata?

equine tapeworm

What is the common name for Anoplocephala magna?

equine tapeworm

What is the common name for Paranoplocephala mamillana?

equine tapeworm

What is the definitive host for Anoplocephala spp. / Paranoplocephala mamillana

equine

What is the intermediate host for Anoplocephala spp. / Paranoplocephala mamillana

orbatid mite

Where do you find Anoplocephala spp. / Paranoplocephala mamillana

small and large intestine/cecum

How are horses infected with Anoplocephala spp. / Paranoplocephala mamillana

accidental ingestion of oribatid mite

What are clinical signs of Anoplocephala spp. / Paranoplocephala mamillana

colic, enteritis, perforation of the intestine

How is Anoplocephala spp. / Paranoplocephala mamillana diagnosed?

54% of horses have been exposed to tapeworms

gross exam

What is the common name for Theileria equi (Babesia equi)

equine piroplasm, equine theileriosis

Who is the definitive host for Theileria equi (Babesia equi)?

equine

Who is the intermediate host for Theileria equi (Babesia equi)?

dermacentor tick, blood transfer

Where can Theileria equi (Babesia equi) be found?

red blood cells

Theileria equi (Babesia equi) is considered a…

reportable disease

What are clinical signs of Theileria equi (Babesia equi)

anemia, icterus, hemoglobinuria, loss of condition, poor exercise tolerance

How is Theileria equi (Babesia equi) diagnosed?

blood smear, necropsy

How is Theileria equi (Babesia equi) treated?

slaughtering infected animals, vector control, quarantine infected

What is the common name for Sarcocystis neurona?

sarcocystis

What does Sarcocystis neurona cause in horses?

equine protozoal myeloencephalitis (EPM)

Who is the definitive host for Sarcocystis neurona?

opossum

Who is the intermediate host for Sarcocystis neurona?

armadillo, domestic cat, skunk, raccoon

What host is an equine for Sarcocystis neurona?

accidental

What is the infection site for Sarcocystis neurona?

CNS

How do horses get infected with Sarcocystis neurona?

accidental ingestion of opossum feces

What are clinical signs of Equine Protozoal Myeloencephalitis (EPM)

abnormal gait, ataxia, cranial nerve function issues, muscle atrophy

How do you diagnose Equine Protozoal Myeloencephalitis (EPM)?

rule out other neurologic disease, exam, lab test

only 100% is post-mortem

How is Equine Protozoal Myeloencephalitis (EPM) treated?

NSAIDS, diet supplements, Marquis (ponazuril), Protazil (diclazuril), Rebalance (sulfadiazine and pyrimethamine)

Treatment must be continued for many months. Some horses respond completely to treatment while others have permanent neurological deficits

Can you prevent Equine Protozoal Myeloencephalitis (EPM)?

remove opossums

pressure wash and scrub infected areas

keep bins tightly covered

bury dead cats, skunks, raccoons found in/around yard

EPM vaccine (effectiveness hasnt been established)

How can you work to prevent parasites w/o dewormers?

proper pasture cleanliness and management

rotating grazing

remove bot eggs

feed above ground

routine fecal exams

quarantine new horses

What is it recommended to do since worms often become resistant to de-wormers

regular rotation

How often should you treat foals?

at 4 weeks and repeat every 6 weeks until the foal is 2 years old

What should you keep your horse feed from touching?

bedding