Pinworms

Rabbit pinworms (Passalurus ambiguus or Oxyuris ambigua) are a common cosmopolitan intestinal parasite that infects wild and pet rabbits and hares. In the USA, the presence of P. nonanulatus has also sometimes been observed in rabbits.

About the parasite

Passalurus ambiguus is species- and host-specific and only lives in rabbits. They do not pose a public health danger.

Infection is common when the eggs are ingested with food. The larvae develop in the mucus layer of the small intestine and cecum, where they develop into mature adults. They molt twice at 24 hours and on the 3rd day. Female worms deposit their eggs around the anus, which can cause itching and skin inflammation. The worms live around 106 days.

Symptoms

The parasite is often asymptomatic, even in severe infestations. Eggs and occasionally live adult worms can be observed in freshly excreted feces. Once out of the rabbit body, the worms will dry quickly and cannot be seen anymore after 5 minutes.

Rabbits may also scratch and bite at their rear end due to intense irritation.

Diagnosis

Pinworms can be diagnosed by a fecal flotation test. Rarely, the test of a heavily infested rabbit can return negative, but the presence can still be observed in droppings.

Treatment

Drugs that can treat pinworms in rabbits include the following:

• Piperazine adipate: orally for two doses 14 days apart
• Fenbendazole: orally for two doses 10-14 days apart
• Thiabendazole: orally for a single dose
• Mebendazole: orally for a single dose
• Oxibendazole: orally for a single dose

Ivermectin is ineffective against pinworms.

Experiences

• East Coast Rabbit Rescue. (2019). Chloe's story - RIP (Graphic)

Further reading

• Esther van Praag. Passalurus ambiguus
• Dr. Laurie Hess and Dr. Rick Axelson. Pinworms in Rabbits

See also

• Parasites