This study describes clinical and histopathological features, treatment and outcome of cats diagnosed with ocular mycobacteriosis. Cases diagnosed from 2012 to 2017 were reviewed for a) histopathological evidence of ocular (pyo)granulomatous inflammation containing acid-fast bacilli with mycobacterial morphology b) positive mycobacterial culture and/or mycobacterial DNA identified by PCR of ocular tissue or c) presumed mycobacteriosis based on ophthalmic examination and positive interferon-gamma release assay. Twenty-five cats (31 eyes) were included; 14 cats (17/31 eyes, 55%) were blind at presentation (unilateral: n=12 cats; bilateral: n=2 cats); one unilaterally affected cat later became bilaterally blind. Another five cats (7/31 eyes, 23%) became blind after initially being bilaterally visual (unilateral: n=3 cats; bilateral: n=2 cats). The commonest ocular finding was uveitis (87%). The main histopathological features were granulomatous to pyogranulomatous chorioretinitis with retinal detachment, anterior uveitis, optic neuritis, episcleritis, scleritis and/or retrobulbar cellulitis. Nineteen cats (76%) had systemic signs, with disseminated disease being diagnosed in nine; defined by interstitial pulmonary disease, generalized lymphadenopathy and/or non-ocular infection. Nine cats were diagnosed with Mycobacterium bovis, two with M. microti, one with M. tuberculosis complex and one with M. avium-intracellulare complex. The infecting species was unknown in the remaining cats. Combined surgery (enucleation: n=5 cats; biopsy: n=3 cats) and systemic treatment with two or three appropriate antibiotics for two to seven months resulted in remission in eight of the 10 cats treated; however, the cat treated with dual therapy relapsed after eight months. A total of sixteen cats (64%) were euthanized; two were lost follow up.
- Eye diseases
- Interferon gamma release assay
- mycobacterial culture
- retinal detachment