Canine prostate-specific esterase (CPSE) in dogs

What it shows

Canine prostate-specific esterase is an enzyme made by the cells of the prostate gland; more than 90% of the protein in prostatic fluid is CPSE. Its production depends on male hormones, which is why it is described as a marker of androgen stimulation of the prostate. Normally only a small amount leaks into the blood; when the gland grows or is damaged, the blood level rises.

The test is used mainly in intact male dogs to look for benign prostatic hyperplasia (BPH) — a hormone-driven enlargement of the prostate and the most common prostate disorder in intact males. Many dogs with BPH show no signs at all, or only blood in the semen or reduced fertility, so a blood test is a convenient first look. Dogs’ prostates do not make PSA, the marker used in people, so CPSE is a separate, dog-specific test.

Higher than reference — what it may be a sign of

• Benign prostatic hyperplasia — the main reason the test is ordered. In one study of 60 intact male dogs, a raised CPSE picked up 96.6% of dogs with BPH and stayed below the cut-off in 90.3% of dogs without it. CPSE also tended to be higher in older dogs and in dogs with larger prostates.
• Other prostate disease — serum CPSE rises with all forms of prostate disease, and the values do not differ clearly between BPH, prostatitis (inflammation or infection of the prostate) and prostate tumours. In the same study, two of the three dogs without BPH but with a high CPSE had prostatitis.

A high value therefore says “the prostate deserves a closer look”, not which disease it is. The diagnosis rests on examination, ultrasound and, when needed, cytology or a biopsy of the prostate.

Lower than reference

A value within the lab’s reference fits a prostate without marked enlargement. It does not rule out every prostate problem. CPSE production depends on male hormones, and after castration the prostate shrinks over weeks to months, so the test is meant for intact males. Prostate tumours, unlike BPH, occur more often in castrated dogs, and CPSE does not separate a tumour from other prostate disease.

Look at together with

• Prostate ultrasound — the best way to judge the size and structure of the gland.
• Urinalysis — blood in the urine and bacteria can come from the prostate; blood in the urine or from the prepuce is one of the signs of BPH.
• Complete blood count — white blood cells when infection of the prostate is suspected.
• Cytology of prostatic fluid or a fine-needle aspirate — the method used in the study above to confirm the diagnosis.

Units and conversion

CPSE is reported in ng/mL, and this is the only unit used for it, so values from different labs need no conversion. The method and the cut-off still depend on the test kit, so values from different laboratories are best compared with each laboratory’s own reference.

Reference range

The reference range is on your lab’s form. In the study above, values from 61 ng/mL upwards were counted as positive, following the manufacturer of the test kit; your laboratory may use a different limit. The vet reads the number together with the dog’s age, signs and ultrasound findings.

Cats and dogs

Sources

1. Prostatic Diseases in Small Animals. Merck Veterinary Manual, professional version.
2. Kutzler M. Benign Prostatic Hyperplasia in Dogs. Merck Veterinary Manual, professional version, reviewed September 2025.
3. Neoplasms of the Prostate in Dogs. Merck Veterinary Manual, professional version.
4. Pinheiro D et al. Evaluation of biomarker canine-prostate specific arginine esterase (CPSE) for the diagnosis of benign prostatic hyperplasia. BMC Vet Res 2017;13:76.
5. VCA Animal Hospitals. Prostatic Disease in Dogs.