Assessment of menace response in neurologically and ophthalmologically healthy cats

Assessment and interpretation of menace response (MeR) in cats can be challenging. The prevalence of abnormal MeR in healthy cats is unknown. The aim of this study was to prospectively evaluate MeR in visually healthy cats.

Fifty cats without history or clinical evidence of neurological or ophthalmological disease were assessed by two examiners: standing behind the cat (mode A), in front of the cat (mode B), and in front of the cat, covering the contralateral eye (mode C). MeR was scored from 1-5 (absent, weak, moderate, strong, complete). Examination modes were compared concerning presence and score (descriptive statistic, 95% confidence interval, χ² test). This was compared to a three-level scoring system (negative, reduced, positive). Score reproducibility between the two examiners was assessed (Cohen's kappa [κ] test). Video footage allowed self-re-evaluation and evaluation of the second examiner (κ analysis). Learning/tiring effect (McNemar test), influence of age, body weight (Spearman's rho test), skull type (χ² test) and being an indoor or outdoor cat (Mann-Whitney U-test) were evaluated.

MeR was always elicited with at least one technique. Comparable results were obtained with the five- and three-level scoring systems. Mode A achieved strong/complete (positive) MeR in 84.5%, mode B in 82% and mode C in 60%. Exact score reproducibility between the two examiners was slight to fair (κ = 0.208-0.281). Intrarater agreement for video self-assessment (κ = 0.544-0.639), as well as inter-rater agreement (extrinsic video assessment), was moderate to substantial (κ = 0.584-0.645). No learning/tiring effect ( P = 0.530) or association with body weight ( P = 0.897), age ( P = 0.724), skull type ( P >0.05) and being an indoor/outdoor cat ( P = 0.511) were evident.

The majority of visually healthy cats revealed a strong/complete MeR when the contralateral eye remained uncovered, but 40% failed when the contralateral eye was covered. The most reliable examination mode was achieved standing behind the cat.