Clinical findings and treatment of disseminated ‘Mycobacterium avium subspecies hominissuis’ infection in a domestic cat

KANEGI, Ryoji; YASUGI, Mayo; NABETANI, Tomoyo; TANAKA, Toshiyuki; WADA, Yusuke; HIRAI, Kotaro; SUGIURA, Kikuya; HATOYA, Shingo

M. avium infection in cats is usually caused by ingestion of the organism via the environment or contaminated food. Our case was completely kept indoors; therefore, we suspected inapparent infection in youth or infection from polluted water or food. After ingestion, M. avium is phagocytosed by intestinal macrophages and eventually causes diseases due to stress or acquired or inborn immunosuppression [8] . In human and veterinary medicine, some cases of M. avium infection have been diagnosed with blood culture; therefore, hematogenous dissemination of M. avium has been considered [1, 5, 19] . Previously reported clinical findings of MAH infection in cats are lymphadenopathy, skin abscesses, skin granulomas, meningoencephalitis, and lung nodules [3, 15, 20] . In the present study, diffuse parenchymal lung diseases and granulomatous inflammation of the lymph node and liver were observed. We suspected that our case was infected via ingestion of polluted water or food and MAH disseminated to the jejunum lymph nodes, liver, and lungs. MAH infection should therefore be considered a differential diagnosis for lung diseases or granulomatous inflammation of uncertain cause. A previous study identified the same clinical findings and splenomegaly in cats with M. avium infection, though potential subspecies were not analyzed [2] . In the present study, no spleen abnormalities were found with ultrasound imaging or CT scan. However, as we did not perform cytology of the spleen, we should consider the possibility that minute spleen lesions were formed. Further studies will be required to elucidate the relationship between clinical findings and M. avium subspecies.