Exam I - Toxocara spp.

Question 1

What is the common name for Toxocara canis?

Answer 1

Common roundworm

Question 2

Toxocara canis adults measure about ___ cm

Answer 2

Toxocara canis adults measure about 10-15 cm

Question 3

In which organ would you expect to find Toxocara canis adults?

Answer 3

small intestine

Question 4

Describe the appearance of a Toxocara canis egg

Answer 4

dark brown, round, thick pitted shell 85 X 75 um

Question 5

List the possible modes of infection for Toxocara canis.

Answer 5

1. Per os
2. Transplacental (prenatal)
3. Transmammary
4. Paratenic hosts

Question 6

Describe the per os life cycle for Toxocara canis.

Answer 6

1. Eggs with L₂ are infective in the environment in 2-4 weeks.
2. Eggs are ingested, hatch in the small intestine, undergo hepatic-tracheal migration, & return to the small intestine where adults mature and eggs are laid after 4-5 weeks.

This is a common mode of infection in puppies (less than 5 weeks of age)

Question 7

Describe the transplacental life cycle for Toxocara canis.

Answer 7

1. In a pregnant bitch, the L₃ move across the placenta at week 6 of gestation, and are carried to the fetal liver via the circulatory system
2. After birth the nematodes migrate to the stomach and mature in the small intestine.
3. Once infected, the bitch will usually harbor sufficient larvae to infect all her subsequent litters.

THIS IS THE MOST COMMON ROUTE OF INFECTION IN PUPS

Question 8

Describe the transmammary life cycle for Toxocara canis.

Answer 8

During the first 3 weeks of lactation, the suckling pup may be infected by L₃. There is no migration in the pup following infection by this route,

Question 9

List some potential clinical signs associated with Toxocara canis.

Answer 9

Depends on the age of the dog, site of infection, & age of nematodes

• Pneumonia from larval migration through the lung
• Eosinophilia from chronic infection
• Vomition and diarrhea
• intestinal obstruction from large number of adults
• possible anemia
• pot belly appearance

Question 10

What would you recommend to a client to help prevent Toxocara canis?

Answer 10

management of environment & use of anthelminthics

Question 11

What might humans have to be worried about with regard to Toxocara canis?

Answer 11

Visceral Larval Migrans

Visceral larval migrans is invasion of visceral tissues in humans by parasites of animals. This condition occurs commonly in children. Limited to liver, eye, brain, heart, and lungs.

Question 12

How often should adult dogs be treated for Toxocara canis?

Answer 12

every 3 - 6 months

Question 13

Which diagnostic tool would you use to diagnose Toxocara canis?

Answer 13

fecal flotation

Question 14

What is the common name for Toxocara cati?

Answer 14

Common roundworm

Question 15

What is the final host forToxocara cati?

Answer 15

Cats.

Question 16

Is the Toxocara cati life cycle direct or indirect?

Answer 16

direct.

Question 17

List the possible modes of infection for Toxocara cati.

Which is most common?

Answer 17

Per os (most common)

Transmammary

paratenic hosts

Question 18

What is the site of infection for Toxocara cati?

Answer 18

small intestine.