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Questions and Answers
What describes the larval migration pattern of Toxascaris leonina in host animals?
What describes the larval migration pattern of Toxascaris leonina in host animals?
Which of the following statements about the transmission routes of ascarids is accurate?
Which of the following statements about the transmission routes of ascarids is accurate?
What is the prepatent period for Toxocara leonina in dogs?
What is the prepatent period for Toxocara leonina in dogs?
How does somatic migration of larvae typically manifest in older pets?
How does somatic migration of larvae typically manifest in older pets?
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What impact does a heavy Ascarid infestation in puppies typically have?
What impact does a heavy Ascarid infestation in puppies typically have?
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What is a common consequence of Visceral Larva Migrans in the lungs?
What is a common consequence of Visceral Larva Migrans in the lungs?
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Which drug is most effective in killing adult ascarids in dogs and cats?
Which drug is most effective in killing adult ascarids in dogs and cats?
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In which organ might Ocular Larva Migrans lead to severe complications?
In which organ might Ocular Larva Migrans lead to severe complications?
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What is the recommended treatment for puppies starting at 2 weeks of age for ascarids?
What is the recommended treatment for puppies starting at 2 weeks of age for ascarids?
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What is the treatment regimen for pregnant bitches against larval ascarids?
What is the treatment regimen for pregnant bitches against larval ascarids?
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Which option describes the recommended frequency of treatment with Fenbendazole for larval ascarids?
Which option describes the recommended frequency of treatment with Fenbendazole for larval ascarids?
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What is a potential effect of somatic migration in older pets relating to fungal infections?
What is a potential effect of somatic migration in older pets relating to fungal infections?
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What is the primary aim of ensuring client education regarding ascarids?
What is the primary aim of ensuring client education regarding ascarids?
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What is the typical duration for ascarid ova to become infective in dogs?
What is the typical duration for ascarid ova to become infective in dogs?
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In which location do adult ascarid worms typically reside in their definitive hosts?
In which location do adult ascarid worms typically reside in their definitive hosts?
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What type of transmission occurs when larvae migrate to the fetus through the placenta?
What type of transmission occurs when larvae migrate to the fetus through the placenta?
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How do infective ascarid ova generally enter the body of a new definitive host?
How do infective ascarid ova generally enter the body of a new definitive host?
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Which ascarid transmission route is considered the primary method in puppies?
Which ascarid transmission route is considered the primary method in puppies?
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Which statement about the larvae of ascarids in older pets is true?
Which statement about the larvae of ascarids in older pets is true?
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What impact do ascarid infestations have on puppies?
What impact do ascarid infestations have on puppies?
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Which characteristic is NOT true regarding ascarid ova?
Which characteristic is NOT true regarding ascarid ova?
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What is the main method through which ascarids infect their next host after leaving the definitive host?
What is the main method through which ascarids infect their next host after leaving the definitive host?
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What type of environment do infective ascarid ova thrive in?
What type of environment do infective ascarid ova thrive in?
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Which stage of development follows the migration of larvae from the alveoli back to the small intestine?
Which stage of development follows the migration of larvae from the alveoli back to the small intestine?
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What method is primarily responsible for the transmission of ascarids in young kittens?
What method is primarily responsible for the transmission of ascarids in young kittens?
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What is the primary difference between tracheal and somatic migration of larvae?
What is the primary difference between tracheal and somatic migration of larvae?
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Which of the following species does NOT experience transplacental or transmammary transmission of ascarids?
Which of the following species does NOT experience transplacental or transmammary transmission of ascarids?
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What is the prepatent period for Toxocara cati?
What is the prepatent period for Toxocara cati?
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In which age group are encysted larvae reactivated in bitches?
In which age group are encysted larvae reactivated in bitches?
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What is the typical outcome of mucosal migration in larvae?
What is the typical outcome of mucosal migration in larvae?
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How long does it take for Toxocara canis ova to become infective?
How long does it take for Toxocara canis ova to become infective?
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What condition does somatic migration lead to in adult animals?
What condition does somatic migration lead to in adult animals?
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Which type of host is important in the life cycle of Toxascaris leonina?
Which type of host is important in the life cycle of Toxascaris leonina?
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What is the role of paratenic hosts in the transmission of Toxocara canis?
What is the role of paratenic hosts in the transmission of Toxocara canis?
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What occurs during the tracheal migration of Toxocara canis larvae?
What occurs during the tracheal migration of Toxocara canis larvae?
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Which age group of dogs is most commonly associated with the tracheal migration pattern of Toxocara canis?
Which age group of dogs is most commonly associated with the tracheal migration pattern of Toxocara canis?
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What is a consequence of somatic migration in older puppies and adult dogs?
What is a consequence of somatic migration in older puppies and adult dogs?
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Which aspect of ascarid infestations is crucial for the final maturation of ascarids?
Which aspect of ascarid infestations is crucial for the final maturation of ascarids?
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How long does it typically take for Toxocara canis eggs to appear in feces after infestation?
How long does it typically take for Toxocara canis eggs to appear in feces after infestation?
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Which transmission route of Toxocara canis is considered less common compared to transplacental transmission?
Which transmission route of Toxocara canis is considered less common compared to transplacental transmission?
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What is a significant impact of ascarid infestations in animals?
What is a significant impact of ascarid infestations in animals?
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Which of the following best describes the lifecycle completion of Toxocara canis?
Which of the following best describes the lifecycle completion of Toxocara canis?
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What triggers the mucosal migration to occur in Toxocara canis?
What triggers the mucosal migration to occur in Toxocara canis?
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Study Notes
General Ascarid Information
- Ascarids are large, common nematode parasites
- Their life cycle can be direct or involve a paratenic host (PH), leading to indirect transmission
- Host specificity varies
- Adult worms reside in the host's small intestine
Ascarid Ova
- Ova are passed in the feces of the definitive host (DH)
- Development to infectivity takes 2-4 weeks (Toxascaris leonina needs 1 week)
- Infective ova are environmentally resistant and can survive for years in soil
- Infective ova are ingested by a new DH or a PH (who is subsequently eaten by DH)
Transmission of Companion Animal Ascarids
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Transmission occurs between hosts through oral ingestion of infective ova
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Ova develop into larvae in the stomach/small intestine of a new host
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Larvae may migrate through the host's body
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Adult worms eventually lodge in the small intestine to reproduce
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The cycle repeats
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Transplacental transmission is a primary route for puppies, but not T. catti (cats)
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This transmission occurs in the pregnant host in approximately 42 days of gestation
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The puppy is born with the infection and adult worms lodge in their small intestine
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They begin to pass ova into feces at 21 days of age
Transmission Summary
- Oral transmission of ova from infected to new hosts
- Transplacental transmission in puppies, potentially in later stages of gestation
- Transmammary is less common than transplacental in puppies (and in kittens)
- Larvae in intermediate hosts (paratenic host) may support another transmission route
Migration of Ascarid Larvae
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Mucosal migration involves larvae burrowing into the small intestine, maturing, and then returning to the lumen
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Tracheal migration- larvae migrate through the liver, vena cava, heart to lungs, to trachea, and then intestines to mature
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Somatic migration- larvae enter circulatory system, migrating to various organs and tissues (commonly muscle and kidneys) which results in encysted larvae
Canine Ascarid (Toxocara canis)
- Definitive host is dogs
- Ova are slightly larger than Toxocara cati
- Zoonotic
- 2-4 weeks ovum infectivity period
- Transplacental transmission is the most important transmission route in puppies
- Various transmission types (oral, transplacental, transmammary, paratenic)
- Important that the species of infecting worm is known as this impacts treatment regimens
Feline Ascarid (Toxocara cati)
- Definitive host (DH) is cats
- Ova morphology is very similar to T. canis
- Zoonotic
- Transmammary is the most important transmission route in kittens
- Larval migration including mucosal, somatic, and tracheal
Toxascaris leonina
- Affects both dogs and cats.
- Oral transmission is common; ova become infective in 1 week.
- No major issue in placental/transmammary transmission pathways
- Mucosal migration only
- Adults form in intestines and then mature
- Not zoonotic
Clinical Signs of Ascarids
- Clinical signs vary greatly depending on the species of worm, the host, and intensity of infection
- Signs often include unthriftiness (poor body condition), pot-belly, diarrhea, or constipation, poor resistance to other diseases
- In newborn puppies, infections range from subclinical to severe, including intussusception, obstruction, and rupture of the GI tract
Diagnosis
- Adult worms may be present in vomitus or feces
- Definitive diagnosis requires microscopic examination of fecal samples to identify ova (not possible to distinguish T. cati and T. canis ova by microscopic exam alone)
Zoonotic Significance
- Some ascarid species are zoonotic and can infect humans
- Larval migration in humans can cause visceral or ocular larva migrans, leading to various health problems
- Prevention and control of ascarids in companion animals are important to prevent human exposure
Treatment
- Drugs specifically designed to kill adult ascarids (e.g., fenbendazole, milbemycin oxime, piperazine, pyrantel pamoate).
- Treatment regimens can vary based on the species and age of the animal
- Safe for use in pregnant/lactating animals (check with veterinarian regarding any precautions)
Care of Infested Puppies/Kittens
- Ensure good hygiene to prevent reinfection
- Provide proper nutrition and supplement with vitamins and minerals
- Proper housing and living conditions.
Environmental Control
- Fecal material should be removed regularly
- Soil/topsoil should be steam sterilized or treated (eg: prescribed fire) or removed; or consider other long-term solutions (e.g., replacement with concrete or asphalt)
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Description
Discover the key characteristics and transmission mechanisms of ascarid nematode parasites. This quiz covers their life cycle, ova development, and the specifics of transmission in companion animals. Understand how these parasites affect their hosts and the environmental resilience of their eggs.
