Comparison between Ki‐67 index and mitotic index for predicting outcome in canine mast cell tumours

Correlation between Ki67 and mitotic index is moderate. High mitotic index accurately predicted death, but many dogs with low mitotic index also died. Low Ki67 accurately predicted survival, but high Ki67 should not be considered a poor prognostic indicator. A three-tier mitotic index assessment may more accurately predict death due to mast cell tumour.