Tapeworms in Rabbits

Tapeworms (taenia or cestodes) is one of the endoparasites that can affect rabbits. These ribbon-like, flat, segmented worms (with exception of the head) can affect, domestic and wild rabbits as well as the American cottontail, the hare and other leporid species. Their segments are often known as proglottids and are nothing besides the parasite’s eggs.

These segmented worms can occur as adults in the rabbit’s intestine (if they are species that affect this animal) or occur in the subcutaneous tissues, liver, and abdominal cavity, among other places if they occur in larvae or infective form and a bunny is only an intermediary host and not their principal host.  

Also, note that the “adult forms are very rare in hutch‑raised rabbits, but larval forms occasionally are observed” [1]

Furthermore, depending on their specific species, some adult tapeworms can be as short as a centimeter long (such as the Echinococcus multilocularis) while others can be about 10 meters (such as Taenia saginata).

Finally, their proglottids often break off and are passed through feces or move by themselves. This is how they are transmitted.

Rabbit or leporid tapeworm

There are about five species of these cestodes that can live inside a rabbit’s intestinal tract, i.e., the “Cittoiaenia variabilis, Mosgovoyia pectinate Americana, M. perplexa, Monoecocetus Americana, and Ctenotaenia ctenoides.”[2]

Although all these species can potentially affect these pets, the C. variabilis are the most common type found in domesticated rabbits both in Europe and America.

Also, note that the above species of cestodes are not zoonotic and they cannot affect human beings, i.e., they cannot affect human beings even after contact. 

While inside the intestines, their four suckers found on their head attaches to the intestine walls and suck blood from their hosts.

Signs and symptoms 

If they exist in a small population, your pet may not show any clinical signs. However, if they exist in large numbers, you may not the following signs:

• Diarrhea
• Ileus
• Severe pain signs
• Slow growth and emaciation (abnormally thin) despite having their normal appetite.
• Presence of the worm’s segments (which are their reproductive units) in feces (the eggs of tapeworms in rabbit’s poop). Also, although it is rare, these worms may be found stuck on your pet’s anus
• Intestinal wall ulceration on the place of attachment in case of necropsy (tissue death)

Treatment of rabbit tapeworms

For the gastrointestinal tapeworms, treatment is done orally by giving your rabbit a dose of praziquantel (Droncit) of 10mg/kg of body weight. Alternatively, you can go for 100mg/kg of the niclosamide.

A healthy bunny should be able to resist these cestodes and they are usually in small populations and they occur rarely.

Intermediary tapeworm and lifecycle

This involves species that do not affect these pets but use them as their intermediary hosts. They are mainly the species that affect dogs, cats, human beings, and foxes (often considered as their definitive hosts).

Common examples include the Taenia pisiformis (can grow up to 2 meters long) and Taenia serialis (this is a fox and dog tapeworm- definitive hosts). These endoparasites are transmitted to your bunnies when they eat contaminated food or grazes on areas with the worm’s eggs.

Common ones include the following:

The Taenia pisiformis

Bunnies get them by ingesting their eggs. Once ingested, the Taenia pisiformis eggs hatch inside the rabbit’s intestines, into the Cysticercus pisiformis larvae which migrate to the liver before going to the abdominal cavity where they form fluid-filled cystic structures that are oval-shaped.

While in the liver, they can cause “granulomatous hepatitis: inflammation, local necrosis of liver cells, infiltration of white blood cells and scaring.”[3]

In terms of their appearance, the Cysticercus pisiformis, usually appear white in color and they may be noted outside lungs, liver, intestines or body cavity including peritoneal serous liquid in eyes, and they may be calcified inside the brains causing seizures, meningitis, and hydrocephalus.

These cysts are often 2-3 cm in diameter. Although rare, they can sometimes reach up to 8 centimeters or more in diameter. However, they should not be confused with tularemia characterized by white spots on the liver of wild lagomorphs and rodents.

The Taenia serialis

The second type is the Taenia serialis hatches into Coenurus serialis which “migrate to the subcutaneous tissues where they form cysts under the skin.” [4] They will feel like fluctuant swellings that are soft during a palpation test. These cysts will appear white with a head of an immature tapeworm.

The Echinococcus granulosus

This is another cestode whose definitive host is canids as well as any other carnivorous animals. This parasitic cestode requires an intermediary herbivore, which could be a rabbit. Its size is between 2-11cm and has about 2-7 segments, but it can produce about 1000 eggs weekly.

Like the others, once ingested, it hatches in the intestines, crosses the intestinal walls and the “larvae migrate via the blood or lymphatic circulation to organs such as the lungs and liver, but also to the nervous system, brain, spleen, kidney or bone marrow.”[5]

Some clinical signs of these cysts include an increase in kidney size, urination abnormalities, the presence of protein and blood in urine, compression of liver tissues, and respiratory issues in case it affects the lungs.

These cysts can be treated using mebendazole, praziquantel, niclosamide, and albendazole whose results are not guaranteed but can kill up to 65-85% of the cysts

Their lifecycle

The cysts have embryonic tapeworms that can only develop to adult form if inside their definitive host. Should a dog or cats eat carcasses of an infected rabbit, they will begin developing to a mature tapeworm inside the dog’s intestine.  

Risk factors

Heavy infection of the larval stage of tapeworms can “cause liver damage, slowed growth, an enlarged abdomen, and can hinder the movement of infected rabbits, making them more vulnerable to predation.” [6]

During the migration to the liver, the Taenia pisiformis larvae may cause “inflammation of the liver, local hepatocellular necrosis, and hepatic scaring if the condition becomes chronic” [7]. A severe infestation may result in chronic weakness as well as sudden death. If they occupy the pulmonary cavity, they will cause an acute respiratory problem.

Prevention

Deworm your dogs and cats that access the rabbit grazing areas at least three times a year and ensure you properly pick and dispose of your dog’s or cat’s feces if they are not litter trained.

Also, consider rotation grazing of rabbits, and keep their hutches clean and ensure your bunny’s food is not contaminated in any way by feces from dogs or cats.

Additionally, ensure your dogs do not eat any rabbit carcasses as they will complete the lifecycle and your dog will again be infected.

Finally, careful cleaning and proper cooking can get rid of the tapeworm cysts from rabbit meat that has them and avoid feeding hunted bunnies to your dogs, cats or any other carnivorous pet.

Treatment

Since rabbits are only an intermediary host, treatments of the larval stages while inside their hosts are not practical. We emphasize on putting in place preventive measures.

Conclusion

Depending on which exact species of the larvae stages that your bunny has, some may be transmitted to human beings if you eat poorly cooked bunny meat or ingest their eggs.