Parascaris equorum Overview
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Questions and Answers

What is the prepatent period for Parascaris equorum?

  • 4 months
  • 2 months
  • 3 months (correct)
  • 5 months

    • Which age group is primarily affected by Parascaris equorum?

  • Adults over 1 year
  • Foals over 1 year
  • Nursing and weaned foals under 1 year (correct)
  • All ages equally

    • What is a key clinical sign of a patent infestation of Parascaris equorum?

  • Cough
  • Weight gain
  • Reduced weight gain or actual weight loss (correct)
  • Increased appetite

    • Where do adult Parascaris equorum worms primarily reside in the horse?

    <p>Small intestine</p> Signup and view all the answers

    What can result from a heavy burden of Parascaris equorum in foals?

    <p>Intestinal rupture and fatal peritonitis</p> Signup and view all the answers

    How does the infective stage of P.equorum reach the next definitive host?

    <p>Ingestion of infective ova</p> Signup and view all the answers

    Which diagnostic method is used to identify migrating larvae of P.equorum?

    <p>Tracheal wash</p> Signup and view all the answers

    What type of transmission is primarily involved in the life cycle of Parascaris equorum?

    <p>Fecal-oral transmission</p> Signup and view all the answers

    What effect do migrating larvae of P.equorum have on host tissue?

    <p>Cause tissue damage</p> Signup and view all the answers

    Which treatment is effective against Parascaris equorum?

    <p>Ivermectin</p> Signup and view all the answers

    What is the recommended age to begin treatment for foals with anthelmintics?

    <p>8 weeks</p> Signup and view all the answers

    What can happen if anthelmintics that paralyze ascarids are administered to heavily infested foals?

    <p>Impaction and/or complete obstruction may occur</p> Signup and view all the answers

    Why is prevention of P.equorum infestations difficult?

    <p>Ova are highly resistant and can survive for years</p> Signup and view all the answers

    What is one of the recommended sanitation practices before foaling?

    <p>Steam-clean the foaling stall</p> Signup and view all the answers

    At what age do infestation rates in foals significantly decline?

    <p>6 months</p> Signup and view all the answers

    What is the role of high-pressure steam-cleaning regarding P.equorum ova?

    <p>It effectively kills the ova</p> Signup and view all the answers

    What does coprophagic behavior in foals primarily help with?

    <p>Seeding the cecum and colon with necessary bacteria</p> Signup and view all the answers

    What is a common characteristic of female P.equorum in terms of egg laying?

    <p>They can lay millions of eggs daily</p> Signup and view all the answers

    What should be done to a mare just before she gives birth?

    <p>Deworm her the day she foals</p> Signup and view all the answers

    Which statement correctly reflects the longevity of immunity in horses?

    <p>Immunity lasts throughout adult lives</p> Signup and view all the answers

    What is the consequence of larvae migration through the liver and lungs caused by Parascaris equorum?

    <p>It leads to tissue damage and inflammatory reactions.</p> Signup and view all the answers

    What are the characteristic ova of Parascaris equorum important for diagnosing patent infestation?

    <p>Thick-shelled, larger ova.</p> Signup and view all the answers

    What is a clinical sign associated with prepatent infestation of Parascaris equorum?

    <p>Cough and nasal discharge.</p> Signup and view all the answers

    What is a potential severe consequence of heavy infestations of Parascaris equorum in foals?

    <p>Rupture of the intestine and death.</p> Signup and view all the answers

    What role does the tracheal migration of the larvae play in the life cycle of Parascaris equorum?

    <p>It aids in the maturation of larvae into adults.</p> Signup and view all the answers

    During what time frame after ingestion do the ova of Parascaris equorum become infective?

    <p>In approximately 10 days.</p> Signup and view all the answers

    How does the age of the horse influence the immune response to Parascaris equorum?

    <p>Younger horses exhibit a weaker immune response.</p> Signup and view all the answers

    What is an effective method for empirical treatment of suspected prepatent infestation of Parascaris equorum?

    <p>Treatment with anthelmintics and monitoring for improvement.</p> Signup and view all the answers

    What are the expected health effects of patently infested foals from Parascaris equorum?

    <p>They exhibit poor growth and lethargy.</p> Signup and view all the answers

    What timeframe should foals begin treatment with anthelmintics after birth?

    <p>8 weeks of age</p> Signup and view all the answers

    Why is it important to administer lower doses of benzimidazoles to heavily infested foals?

    <p>To reduce the risk of impaction</p> Signup and view all the answers

    What is a significant challenge in preventing Parascaris equorum infestation in foals?

    <p>Ova are unaffected by chemical treatments</p> Signup and view all the answers

    What environmental measures are recommended to reduce the risk of P.equorum infestations?

    <p>Implementing high-pressure steam cleaning</p> Signup and view all the answers

    What is a common behavior of foals that contributes to the spread of Parascaris equorum?

    <p>Coprophagy</p> Signup and view all the answers

    At what age does the infestation rate in foals typically see a significant decline?

    <p>6 months</p> Signup and view all the answers

    What happens to the immunity against P.equorum as horses mature?

    <p>It improves significantly</p> Signup and view all the answers

    What should be done to the mare immediately before she gives birth to manage P.equorum?

    <p>Deworm her on the day of foaling</p> Signup and view all the answers

    Which method is ineffective in eliminating P.equorum ova from the environment?

    <p>Chemical disinfectants</p> Signup and view all the answers

    What is a significant outcome of a heavy infestation of Parascaris equorum in foals when treated improperly?

    <p>Risk of intestinal obstruction</p> Signup and view all the answers

    Study Notes

    Parascaris equorum

    • Largest equine parasite, up to 10 inches long
    • Direct life cycle
    • Prepatent period: 3 months
    • Primarily infects nursing and weaned foals under 1 year old
    • Adults reside in the small intestine
    • Can occupy significant space, potentially causing obstruction and rupture
    • Age-related immunity develops against P. equorum

    P. equorum Life Cycle

    • Highly resistant, sticky eggs passed in feces
    • Eggs become infective within approximately 10 days
    • Fecal-oral transmission (ingestion of infective eggs)
    • Larvae hatch in the small intestine, migrate through the intestinal wall to the liver
    • Larvae then travel to the lungs, across into the alveoli
    • Larvae crawl up the trachea, are swallowed, and migrate to the small intestine
    • Mature into adults
    • Prepatent period: 3 months

    Pathology

    • Migrating larvae cause tissue damage
    • Inflammatory tracts form in the liver
    • Inflammatory nodules form in the lungs
    • Lesions eventually heal, but functional capacity can be reduced, particularly in the lungs

    Clinical Signs

    • Prepatent infestation (larvae): Foals infested at birth may display clinical signs within 4–6 weeks (cough, nasal discharge, "verminous pneumonia")
    • Patent infestation (adults): Older foals present with diarrhea, flatulence, lethargy, poor body condition ("poor doer"), rough hair coat, and enlarged abdomens; reduced weight gain or loss; colic
    • Death can result from impaction and intestinal rupture causing fatal peritonitis

    Diagnosis

    • Prepatent infestation: Foals displaying coughing, nasal discharge; tracheal wash to collect migrating larvae; empirical treatment with anthelmintics and monitoring for improvement; diagnosis sometimes made at necropsy
    • Patent infestation: Fecal float with characteristic (thick shelled, small/smooth shelled) ova

    Treatment

    • Many effective deworming agents (ivermectin, moxidectin, fenbendazole, oxibendazole, pyrantel)
    • Treatment in foals older than 8 weeks, administer at 2-month intervals during their first year of life
    • Treatment warning: Anthelmintics causing paralysis in adult worms can cause impaction. Administer lower doses and repeat after 10-14 days if needed

    Prevention

    • Difficult to prevent due to resistance of ova, longevity, and frequent environmental presence.
    • Female worms lay millions of eggs daily in feces
    • Eggs resist freezing and drying, survive various environmental factors and remain infective for extended periods
    • Chemical disinfectants do not always kill the ova
    • Steam cleaning is effective for destroying ova
    • Wash mares' udder and teats before parturition (birth) to prevent contamination of neonates
    • Infestation rates in foals decrease significantly by 6 months due to age-related resistance and a potent immune response
    • By 12 months, apparent infestations in horses are not common
    • Immunity lasts throughout their adult lives

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    Description

    This quiz covers the essential aspects of the largest equine parasite, Parascaris equorum. Learn about its life cycle, pathology, and the impact on young horses. Test your knowledge of this significant parasite affecting foals under one year old.

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