Dipylidium caninum: Common dog tapeworm.

General Description: This cestode grows up to 50 cm long and is usually light reddish-yellow. The proglottids are elongate and when gravid resemble cucumber seeds. The scolex has 3 to 4 rows of small hooks around its front end.

Life Cycle: Dipylidium caninum infects dogs and cats, and has an indirect life cycle. Intermediate hosts are the dog and cat fleas (Ctenocephalides canis, Ctenocephalides felis), and human fleas (Pulex irritans). The dog louse, Trichodectes canis, may also serve as an intermediate host. These arthropods are infected by eating Dipylidium eggs. The cysticercoid larval form inside the insect infects dogs when ingested during grooming. The prepatent period is 2 to 3 weeks.

Location: Small intestine.

Significance: Dipylidium caninum is the most common tapeworm in dogs and cats, but is not very pathogenic.

Effect on Host: No disease is caused by light infections. Heavier worm burdens compete with the host for ingested food and cause chronic inflammation of the intestine. Animals may lose weight and have rough hair coats. Gravid proglottids that break off from the tapeworm are motile and may cause intense itching of the anal region.

Diagnostic Information: Proglottids may be seen around the anus or in the faeces. Eggs occur in packets and are found in proglottids or occasionally in faeces when some proglottids break down.

Control: Reduction of flea and louse populations reduces Dipylidium infections. Many different effective anthelmintics are available.

Dipylidium, adults attached to wall of small intestine		D. caninum, egg packets
D. Caninum – whole mount
Dipylidium – proglottids in dog faeces		Close up of proglottids