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.