Large language models demonstrate variable diagnostic performance and a systematic risk of undertriage in surgical triage of feline metacarpal and metatarsal fractures.
Objective To evaluate the diagnostic performance of multiple large language models (LLMs) against expert consensus in determining surgical intervention needs for feline metacarpal and metatarsal fractures. Methods In this retrospective study (December 2023 to February 2025), 73 clinical cases of feline metacarpal and metatarsal fractures were evaluated. Two board-certified veterinary orthopedic surgeons established a reference standard for surgical versus conservative management. Five LLMs (ChatGPT, version 5.2 [OpenAI Inc]; Gemini, version 3 Pro [Alphabet Inc]; Grok, version 4.1 [SpaceXAI]; Qwen, version 3.5 [Alibaba Cloud]; and Claude Sonnet, version 4.5 [Anthropic PBC]; and Claude Sonnet, version 4.5 [Anthropic PBC]) assessed anonymized case summaries using a standardized zero-shot prompt. Model recommendations were compared with the reference standard to calculate accuracy, sensitivity, specificity, and the Cohen κ. Results The reference standard classified 49 cases (67.1%) as surgical and 24 (32.9%) as conservative. ChatGPT achieved the highest performance (accuracy, 84.9%; sensitivity, 79.6%; specificity, 95.8%; κ = 0.69). Other models showed lower performance; Qwen and Claude Sonnet failed to identify any surgical cases (0% sensitivity). A systematic bias toward conservative management was observed across all models, causing high false-negative rates (undertriage). Conclusions LLMs demonstrate highly variable diagnostic performance and a systematic risk of undertriage in feline fracture assessment. While top-performing models approach expert-level agreement, others fail in critical clinical scenarios. Clinical Relevance Independent LLM use for surgical decision-making in feline orthopedics is not recommended due to undertriage risks. These tools require strict clinician oversight for preliminary triage.