Mycoplasma-associated polyarthritis in raccoons (Procyon lotor) from the southeastern United States

Arthritis in humans and animals can be caused by various infectious agents some of which are zoonotic so studying them in a One Health context is critical. This report describes four cases of Mycoplasma-associated arthritis in raccoons (Procyon lotor) from the southeastern United States. The cases were submitted between March 2023 and March 2024 from two states (Louisiana and Georgia). Raccoons had lesions of variable severity but included joints with purulent material, pockets of purulent material overlying joints and extending into adjacent subcutis, and abscesses through the subcutis. Three of the four raccoons had co-morbidities that may have contributed to their risk of development of Mycoplasma-associated disease including canine distemper infection, amyloidosis, dental disease, and schistosomiasis, although amyloidosis may have developed secondarily to mycoplasmal disease. Two unique Mycoplasma sequences were detected. Phylogenetically, the two Mycoplasma sequences were most similar to M. phocimorsus which has been associated with human disease after exposure to seals and brown bears and abscesses in domestic cats. However, it is unknown if the two raccoon Mycoplasma represent strains of M. phocimorsus, are M. phocimorsus and a novel species, or are two novel species. Mycoplasma-associated polyarthritis was previously reported in juvenile raccoons in Canada undergoing rehabilitation, but the Mycoplasma sp. was not determined. Collectively, these data suggest Mycoplasma-associated arthritis occurs across a broad range and in both juvenile and adult raccoons. Further work is needed to determine if underlying conditions or coinfections are associated with the development of Mycoplasma-associated disease in raccoons and if the raccoon-infecting Mycoplasma are zoonotic.