From the December 2020 Newsletter:
A 22-year-old, miniature horse gelding was euthanized with a suspected strangulating lipoma and presented for postmortem examination. Due to neurologic signs, including circling and falling into his stall, rabies virus examination was requested.
Grossly, the right kidney contained multifocal to coalescing foci ranging in size up to 2 mm. On section, the foci bulged and were homogeneously white. No other gross lesions were appreciated. The white foci in the kidney corresponded to granulomas centered on small nematode larvae, microscopically. The nematode larvae were characterized by a rhabditiform esophagus composed of a corpus, isthmus, and bulb and a tapered tail. These are hallmark features of Halicephalobus gingivalis. Similar, though fewer, nematodes and inflammation were present in the cerebrum and brainstem.
H. gingivalis nematodes are free-living worms in the soil and decaying organic matter. They can infect both horses and people and, thus, are considered to have zoonotic potential. Clinical signs typically reflect the organs that are infected, which are most commonly kidney and brain, as well as lymph nodes, adrenal glands, and the oronasal cavity. As this is a disseminated infection, however, any organ can be affected. This is the first record of H. gingivalis diagnosed at the VDL. Travel history of the horse was not provided.