Canis ISSN: 2398-2942

Ascaridosis

Introduction

• Cause: ascaridosis includes infection with Toxocara canis and Toxascaris leonina.
• T. canisis the ascarid most implicated as a zoonosis - cause of visceral larva migrans, ocular larva migrans and covert toxocarosis in humans.
• Signs: most likely in young pups with a heavy T. canis infection → pot-belly, thin.Occasional intestinal obstruction with heavy burdens.
• Intestinal ascarid burdens may be present in older dogs but unlikely to be associated with clinical signs.
• Diagnosis: signs, fecal egg counts.
• Treatment: anthelmintic.
• Prognosis: good if appropriate treatment.

Pathogenesis

Etiology

• Large intestinal burden ofT. canisin the small intestine of pups.

Predisposing factors

• Poor worm control.
• Endemic high level ofT. canisinfection in dogs and in the kennel environment.

Pathophysiology

• SeeToxocara canislife cycle .
• 3 main sources of infection for young pups:
  • Transmammary transmission of larvae that have been resting in the bitch's tissues as somatic larvae.
  • Transmission in the milk - normally a minor route accounting for less than 5% of infection unless the bitch was infected in late pregnancy.
  • Embryonated eggs containing L3 larvae (previously considered to be L2) in the nest/run environment.
• T. canislarvae carry out hepatotracheal migration in pups.
• Rapidly develop to adult worms in the small intestine.
• First worms mature by approximately 2.5 weeks of age.
• Small number of worms well-tolerated.
• Presence associated with villous atrophy, malabsorption, increased thickness of intestinal muscle layers Toxocara canis.
• Larger worm burden: pot-bellied appearance and more marked malabsorption, etc.
• The larger the worm burden the higher the risk of intestinal obstruction or death.

• Villous atrophy within the small intestine leading to malabsorption Malabsorption.

Timecourse

• Acute signs may be seen in pups from the time that substantial numbers ofT. canisenter and mature in the intestine.
• The higher the burden the earlier clinical signs will be seen.
• Normally unweaned pups (3-8 weeks approximately).
• Ill-thrift may be seen in pups particularly in this age range.

Epidemiology

• SeeToxocara canis Toxocara canis.

Diagnosis

Treatment

Prevention

Outcomes