Hepatic coccidiosis, caused by Eimeria stiedae.  Some rabbits are asymptomatic; however, the disease can be fatal, especially in young rabbits. Heavily infected rabbits show signs related to decreased hepatic function and bile duct obstruction. Anorexia, debilitation and diarrhea or constipation can occur. The abdomen might be enlarged, and the animal may be icteric. Infection results from ingesting sporulated oocysts that undergo excystation in the duodenum.
Enlargement of the liver, gall bladder, and bile duct may be seen at necropsy with multi-focal nodules caused by hyperplasia and cystic enlargement of the bile duct epithelium. Various life cycle stages of the organism may be seen histopathologically with oocysts in bile duct lumina.

Opisthorchids are trematodes residing in the gall bladder and bile duct of many vertebrates. The eggs (22-35µm X 11-19 µm) are thin-shelled and operculated with a yellowish-brown color. The presence of a prominent lip around the rim of the operculum and the adjacent shell is a distinguishing feature of these eggs.
In cats, Metorchis conjunctus, M. albidus, and Amphimerus pseudofelineus are the Opisthorchids reported from parts of the United States and Canada. Parasites belonging to the family Opisthorchiidae have an indirect life cycle involving two intermediate hosts- mollusks and freshwater fish.  Opisthorchid infection is not known to create severe health effects in the definitive host.  Nevertheless, there have been occasional reports of clinically significant liver damage.  Eggs can be recovered using centrifugal fecal flotation, but sedimentation tests are preferred.

​Caparinia tripilis are Psoroptid mites that infest hedgehogs as well as other mammals.  The mites feed on skin cells and epidermal debris.  Two species are known to infest hedgehogs, C. tripilis and C. erinacei, with the first one being more pathogenic and forming clusters on its host.   Caparinia tripilis has a posterior end of the abdomen with trilobate laminate projection on either side and contain a long seta (Image 3) while C. erinacei has two bilobate laminate projections. 
The mites burrow into the skin of ears, head, and sides of the legs causing irritation, pruritus, and self-trauma that can lead to infection.   On this case, the mucoid diarrhea was not caused by the mite infestation.

Hypoderma lineatum, also called heel flies or gadflies. The adult flies deposit eggs on the hair of cattle, deer and sometimes horses. The eggs hatch within a week and migrate through the connective tissues of the host. The larva of H. lineatum accumulate in the esophagus during migration and remain there for about 3 months. After, they migrate to the subcutaneous tissues of the back, forming lumps or warbles and cutting breathing holes in the skin of the host. When the larva emerges from the warble they measure approximately 25 mm long with a light brown color.

​Ornithonyssus bacoti. Known as the “tropical rate mite” is a bloodsucking mesostigmatid mite. They can be distinguished from Liponyssoides sanguineus, another mite that typically parasitizes rodents, by observing an anterior anus within the anal plate compared to a centrally located anus in Liponyssoides. Liponyssoides also has long whip-like chelicerae whereas Ornithonyssus have well-developed chelicerae that are the same in diameter throughout. Ornithonyssus is zoonotic and results in “Tropical Rat Dermatitis” in humans. It also harbors other pathogenic agents such as Francisella tularensis, Yersenia pestis, Borrelia burgdorferi and Rickettsia typhi.