Tapeworms: rabbit as the definitive host

 

Esther van Praag, Ph.D.

 

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Warning: this file contains pictures that may be distressing for some persons.

Cestodes

Several species of flat-segmented worms, or tapeworms, have the capacity to infest wild or domestic rabbits and wild lagomorph species, including the American cottontail rabbit and hares. These worms can develop into mature, reproducing tapeworms.  These include:

ˇ     Monoecocestus americanus, the porcupine tapeworm;

ˇ     Ctenotaenia ctenoides;

ˇ     Cittotaenia variabilis, the rabbit tapeworm;

ˇ     Mosgovoyia pectinata americana or M. perplexa;

Tapeworm infestation is a rare condition in pet rabbits, primarily caused by Cittotaenia variabilis.

The life cycle of these worms is not well understood at present. It is believed that infected arthropods, such as oribatid mites (mites living in the soil), may act as vectors for the transmission of the rabbit tapeworm, Cittotaenia variabilis. The rabbit ingests the mites while grazing or consuming contaminated hay. The larval form will develop in the abdomen and the liver. Adult stages of the parasite are found in the intestine. Its dimensions are 1 cm in width and 20 cm in length. 

Cittotaenia variabilis is distinguished by a scolex (head) with four suckers that attach to the intestinal wall.

Clinical signs

If the number of tapeworms is small, no clinical signs will be observed. In the event of a severe infection, there may be indications of diarrhea, bloating, ileus, and severe pain. It is possible that the rabbit will grow slowly and appear abnormally thin despite having a normal appetite. 

Proglottis (reproductive segments) can be found in the feces:

This is a specimen of a flatworm, potentially Cittotaenia variabilis, that was discovered among the fecal matter of a pet rabbit.

This rabbit is fed a diet of fresh dandelion and broadleaf plantain, from the field, where wild cottontail rabbits can be observed.

Picture: Wei in Massachusets (USA)

In rare cases, the worm may be visible protruding from the anus.

A necropsy may reveal ulceration at the site of the worm's attachment to the intestinal wall.

Tapeworms affecting rabbits do not pose a zoonotic threat. Consequently, contact with contaminated fecal material or proglottids does not result in the transmission of these parasites to humans.

Treatment

Praziquantel

10 mg/kg

PO

5-10 mg/kg

SC, IM

Niclosamide

100 mg/kg

PO

Please consult the following list to understand the meaning of the abbreviations, click here.

Following treatment with praziquantel, the remaining portion of the tapeworm has been expelled.

The expelled worm is covered by fecal material and mucus. Picture: Wei

Good sanitation of the living environment of the rabbit is also necessary.

Acknowlegement

I would like to express our gratitude to Wei in Massachusetts, USA, for sharing this rare finding with her rabbit, Bunbun, and for granting me permission to use the pictures.

Further information:

Manning et al. The biology of the laboratory rabbit. 2nd ed. London, UK, 1994.

Sadler KC. Common diseases and Parasites of Cottontails, Missouri Dept. of Conservation.

Pinto RM, et al. Helminths of rabbits (Lagomorpha, Leporidae) deposited in the Helminthological Collection of the Oswaldo Cruz Institute. Rev. Bras. Zool. 2004, v. 21, n. 3, pp. 599-604.

Soltysiak Z, Bednarski M, Piekarska J. Wagrzyca watroby królika. Medycyna Wet. 2007, 63:1255-1257.

 

 

  

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