Adult can be up to 10 cm in length, with a very short prepatent period of 1 - 2 weeks.
Species which are pathogenic to dogs include:
- Toxascaris leonina
Dogs become infected by eating intermediate hosts (usually rodents) where encysted larvae reside within the intestinal epithelium. Larvae become proteolytically activated in the dog stomach. In the small intestine, they penetrate the mucosa and develop into adults, activatng a Th-2 helper cell response by the host. They finally return to the lumen of the intestine as adult, where they lay eggs.
The short life cycle enables this parasite to persist in even well-sanitized colonies of dogs. Fecal eggs can be detected in pups from 6 weeks of age in kennels endemically infected with this parasite.
Infections in young dogs normally result in characteristic underweight, pot-bellied puppies, which are often anemic. Deaths associated with heavy infestations in young dogs is uncommon, compared with Toxocara canis and Ancylostoma caninum.
Adult dogs are often asymptomatically infected, although poor coat, polyphagia and anemia can also occur.
Diagnosis is usually based on coprological examinations using fecal floatation devices.
Supportive diagnosis can be made with ELISA assays of feces and blood samples, and PCR assays can be used for accurate speciation of the parasite.
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