Abstract: The invention relates to an analysis method for the in vitro diagnosis of benign prostatic hyperplasia (BPH) in a dog, using the CPSE contained in biological fluid samples collected from the dog as well as biological molecules specifically binding CPSE. The invention is characterised in that it includes the following steps: a. collecting a biological fluid sample from a dog; b. measuring the canine prostate specific esterase (CPSE) of said sample; c. comparing said measured CPSE concentration with a reference value, said value being from around 34 ng/ml to around 102.4 ng/ml for serum or plasma, preferably around 61 ng/ml; d. using the CPSE concentration as a BPH marker; and e. diagnosing BPH in a dog when measured CPSE concentrations in said sample exceed said reference value.