Ocular mycobacterial lesions in cats

Area of Science:

• Veterinary Pathology
• Ophthalmology
• Infectious Diseases

Background:

• Ocular mycobacterial infections are an under-recognized cause of feline morbidity.
• These infections can lead to significant ocular lesions and visual impairment.

Purpose of the Study:

• To investigate the distribution, histopathology, and immune cell response in feline ocular mycobacteriosis.
• To characterize the primary site of lesion development and associated inflammatory patterns.

Main Methods:

• Histological examination (H&E, Masson's trichrome) and inflammation scoring.
• Acid-fast bacilli detection (Ziehl-Neelsen) and immunohistochemistry (Iba1, calprotectin, CD3, Pax5).
• Analysis of 24 feline cases with ocular mycobacteriosis.

Main Results:

• Posterior/panuveitis with retinitis (83%) and retinal detachment (80%) were common.
• Choroidal lesions showed the highest inflammation scores and the most acid-fast bacilli.
• Inflammation was granulomatous/pyogranulomatous (macrophages, granulocytes, monocytes) or lymphoplasmacytic in iritis cases.

Conclusions:

• The choroid is a primary site for feline ocular mycobacterial lesion development.
• Inflammatory changes correlate with mycobacterial presence in ocular tissues.
• Tuberculosis is the predominant diagnosis (91%), emphasizing the zoonotic potential and need for veterinary vigilance.