Microscopy

Eggs
Dipylidium caninum eggs are round to oval (average size 35 to 40 µm; range 31 to 50 µm by 27 to 48 µm) and contain an oncosphere that has 6 hooklets.  Proglottids of D. caninum contain characteristic egg packets that are round to ovoid and contain 5 to 15 or more eggs each.

A	B

A: D. caninum egg packet, containing 8 visible eggs, in a wet mount.
B: D. caninum eggs clumped together in a wet mount; image taken at 400× magnification.  Note that hooklets in the some of the eggs are visible.

Proglottids
Dipylidium caninum proglottids (average mature size 12 mm × 3 mm) have two genital pores, one in the middle of each lateral margin.  Proglottids may be passed singly or in chains, and occasionally may be seen dangling from the anus.  They are pumpkin seed-shaped when passed and often resemble rice grains when dried.

C	D

C: D. caninum proglottid under a dissecting microscope cleared with lactophenol.
D: D. caninum proglottid partially cleared with lactophenol, showing eggs and egg packets.

Scolex
The scolex of Dipylidium caninum is conical-shaped and has four suckers.  There is also a retractable rostellum armed with several rings of small spines, used for anchoring into the host’s tissue.

E

E: D. caninum scolex.

Macroscopic (Gross) Observations

F

F: Adult tapeworm of Dipylidium caninum; adults measure 10-70 cm long.  The scolex of the worm is very narrow and the proglottids get larger as they mature.