Rater agreement on gait assessment during neurologic examination of horses.

Abstract

BACKGROUND: Reproducible and accurate recognition of presence and severity of ataxia in horses with neurologic disease is important when establishing a diagnosis, assessing response to treatment, and making recommendations that might influence rider safety or a decision for euthanasia. OBJECTIVES: To determine the reproducibility and validity of the gait assessment component in the neurologic examination of horses. ANIMALS: Twenty-five horses referred to the Royal Veterinary College Equine Referral Hospital for neurological assessment (n = 15), purchased (without a history of gait abnormalities) for an unrelated study (n = 5), or donated because of perceived ataxia (n = 5). METHODS: Utilizing a prospective study design; a group of board-certified medicine (n = 2) and surgery (n = 2) clinicians and residents (n = 2) assessed components of the equine neurologic examination (live and video recorded) and assigned individual and overall neurologic gait deficit grades (0-4). Inter-rater agreement and assessment-reassessment reliability were quantified using intraclass correlation coefficients (ICC). RESULTS: The ICCs of the selected components of the neurologic examination ranged from 0 to 0.69. "Backing up" and "recognition of mistakes over obstacle" were the only components with an ICC > 0.6. Assessment-reassessment agreement was poor to fair. The agreement on gait grading was good overall (ICC = 0.74), but poor for grades ≤ 1 (ICC = 0.08) and fair for ataxia grades ≥ 2 (ICC = 0.43). Clinicians with prior knowledge of a possible gait abnormality were more likely to assign a grade higher than the median grade. CONCLUSION AND CLINICAL IMPORTANCE: Clinicians should be aware of poor agreement even between skilled observers of equine gait abnormalities, especially when the clinical signs are subtle.