Internal Parasites Flashcards
What issues do internal parasites cause in horses
Gastrointestinal lesions, oral lesions, liver damage, stomach and intestinal lining issues, telescoping intestines, impactions, colic
What are the largest concerns in adult horses
Small strongyles and tapeworms
Ascarids are most likely to be found where?
In foals and weanlings
What are the three species of large strongyles that affect horses.
Strongyles vulgaris, strongylus edentates, and strongylus equinus
How do horses get large strongyles?
By ingesting them in the mouth while the horse grazes.
What does strongylus vulgaris do once ingested?
Migrate to the large intestine and they can then migrate to the blood vessels and burrow through the walls of arteries and disrupt blood flow.
S. Vulgaris is aka
Blood worms
What is the most damaging type of large strongyle
S. Vulgaris
What do S. Edentates and S. Equinus do once they are ingested?
Migrate from the digestive tract to the liver and back to the large intestines
Currently large strongyles are not a large concern for domestic horses because…
Treatment strategies from decades ago substantially reduced their presence
Small strongyles aka
Cyathostomes
How is the life cycle of the small strongyle similar to the large strongyle
They are found on pasture grasses, ingested as larvae, and the. Move through the digestive system.
Once the small strongyle reach large intestine…
They do not migrate to other organs and tissues
What is unique about small strongyles
They often burrow into the walls of the large colon and cecum, becoming encysted
What makes management of small strongyles difficult?
While encysted they can remain in the body for up to 2 years and are not affected by most dewormer treatments
Small strongyles wait until conditions are ideal and then…
Emerge from intestinal wall to mature and produce eggs.
What is the scientific names of ascarids? Aka…
Parascaris equorum…round worms
What type of horses do ascarids most commonly affect?
Younger foals and weanlings(most horses develope immunity by the time they are yearlings)
Name three surfaces ascarids are found on.
Pasture grass, buckets, troughs, and a mare’s udders
What happens to ascarids once they are ingested?
1)they develop into larvae in the small intestine
2)the hatched larvae migrate through tissues moving from liver to the lungs
3) the parasites are coughed up swallowed and migrated back to the SI for maturation
What is the most common species of tape worms found in horses?
Anoplocephala perfoliata
What makes tape worms unique?
They have 2 hosts in their life cycle the first is the probated mite and the second is the horse
Horses consume the tape worm carrieing mites…
While grazing
After injestion the the mites release the tapeworms in the…
Small intestine
Once in the ileocecal junction what do the tapeworms do?
Attach to the guy wall and may cause inflammation of the DT
Along with colic obstruction ulceration or thickening of the intestines
What is the scientific name for pinworms?
Oxyruris equi
What do pin worms do
Cause irritation around the anus and induce hair loss from scratching
What is unique about pinworms?
They do not cause much internal damage.
What makes bits unique?
They are both internal and external parasites
What is the most common species of bot fly?
Gasterophilius intestinalis
What stimulates bot eggs to hatch?
Horse saliva
Bot eggs burrow in a horses gums for
About 4 weeks
How long do bots stay in the stomach lining?
9 months and then are passed through manure
What is the scientific name for thread worms?
Strongyloides westeri
What are the three ways foals become infected by threadworms
- Through mare milk
- By the larvae penetrating the foal’s skin
- From the environment
Infestation of thread worms can cause
Diarrhea and dehydration
