Answer to Quiz Question

Back to Lab 4 Demos


A.     Left egg is Toxocara canis     Right eggs are Toxascaris leonina


B.  Toxocara canis may have entered the puppy in utero.   The larvae crossed the placenta and arrested in the liver of the fetus.  After the pup was born the larvae resumed their migration from the liver, through the heart to the lungs where they broke out of the capillaries and into the alveoli, causing symptoms of pneumonia.  However since the other eggs belong to T. leonina which has a 11 week pre-patent period, it is likely that if the T. canis caused the respiratory symptoms 2 weeks ago, then the dog was infected orally with infectious eggs (with L2 in them) at about that time.

Toxascaris leonina would have (most likely) entered as an infectious egg (with L2 in it).  There is no tracheal migration in the pup due to Toxascaris leonina.

So, the answer to "B" is Toxocara canis.

                                               RETURN TO LAB 4