• Taenia hydatigena
• Taenia multiceps
• Taenia ovis
• Taenia pisiformis

Taenia hydatigena (synonym: Taenia marginata )

General Description: Taenia hydatigena is a large tapeworm, 75 to 500cm in length. Gravid proglottids are wider than long, measuring 10 to 14mm by 4 to 7mm. This species is difficult to distinguish from other taenid tapeworms.

Life Cycle: This tapeworm has an indirect life cycle, with sheep, goats, cattle, pigs or other mammals as intermediate hosts. Hexacanth embryos develop in eggs on pasture and are ingested by intermediate hosts. In these animals the metacestode known as Cysticercus tenuicollis matures in the peritoneal (abdominal) cavity and occupies a cyst 5cm or more in diameter. These metacestodes are infective for about 2 to 3 months after entering the intermediate host. Dogs are infected by ingesting tissue containing metacestodes. Digestion releases the immature scolex, which grows and produces the adult tapeworm. The prepatent period is about 7 to 8 weeks.

Location: Small intestine.

Significance: The disease produced in dogs by this tapeworm is less severe than that produced in sheep, goats and cattle, which may be killed by metacestodes. Carcasses may be condemned at slaughter because of the presence of Cysticercus tenuicollis.

Effect on Host: Parasite loads of these tapeworms in the dog are usually harmless, but large numbers may cause gastrointestinal inflammation which causes diarrhoea.

Diagnostic Information: Proglottids containing eggs appear in faeces. If any segments have decomposed or been broken, Taenia -type eggs may be found.

Control: Dogs should be prevented from eating wild ruminants. Many anthelmintics effective against adult tapeworms are available. Uncooked sheep meat should be deep frozen for at least 10 days before feeding to dogs.

Taenia multiceps (Synonym: Multiceps multiceps )

General Description: Taenia -like tapeworm, 40-100cm long. Gravid proglottides are 8-12mm wide and 3-4mm long.

Life Cycle: Indirect. Intermediate hosts are sheep, goats, cattle horses, other ungulates, rodents and rarely man. In sheep and goats, following ingestion of the infective hexacanth embryo, metacestodes (Coenurus cerebralis ) develop in the brain causing the nervous disease known as "gid", "sturdy" or "staggers". Metacestodes develop in the muscles of rodent intermediate hosts. Ingestion of tissue from intermediate hosts by dogs results in the development of adult tapeworms.

Location: Small intestine.

Significance: The significance of this tapeworm is from the serious nervous complications it produces in the livestock intermediate hosts.

Effect on Host: Similar to Taenia hydatigena.

Diagnostic Information: Similar to Taenia hydatigena.

Control: Ingestion of brains from infected sheep, goats, cattle or other possible intermediate hosts should be avoided. Effective anthelmintics are available to treat infected dogs.

Taenia mulitceps – adults attached to wall of small intestine		Taenia multiceps – cysts on liver of mouse		Larval stage (Coernurus) in sheep brain. Adult worm in dog

Taenia ovis (sheep measles)

General Description: Another large tapeworm which can grow up to 1m in length.

Life Cycle: Indirect, similar to that of Taenia hydatigena. The metacestode, cysticencus ovis is found under the epicardium, and the pleura of the diaphragm but also in other organs and muscle.

Location: Small intestine.

Significance: Mostly harmless to the sheep but as with Taenia hydatigena the presence of cysts in the carcass may lead to condemnation at slaughter.

Effect on Host: Of little significance to the dog.

Diagnostic Information: Proglottids containing eggs appear in faeces.

Control: Dogs should be prevented from eating uncooked sheep meat or meat should be deep frozen for at least 10 days.

Taenia pisiformis

General Description: This is a large tapeworm, up to 220cm long. The gravid proglottides are 8 to 10mm wide and 4 to 5mm long.

Life Cycle: Indirect, similar to Taenia hydatigena except that the intermediate hosts are rodents, mainly rabbits and hares. Metacestode cysts in these animals are pea-sized and located in the peritoneal cavity.

Location: Small intestine.

Significance: Taenia pisiformis is not often a threat to dogs; only intermediate hosts are seriously compromised. However, when present in large numbers they can cause intestinal obstruction.

Effect on Host: Similar to that of Taenia hydatigena.

Diagnostic Information: Proglottides appear in faeces; if any segments have decomposed in faeces, Taenia -type eggs may be found.

Control: Dogs should be prevented from eating rodents, especially rabbits and hares. Anthelmintics will cure infections with tapeworms.

Scanning electron microscope photo – scolex – T. pisiformis		Cysticercus		Cysticercus in rabbit – adult occurs in dog