Enlarged, mineralised prostate in a neutered dog
11-year-old crossbreed neutered at 2 years old, with tenesmus, stranguria and weight loss. On the lateral radiograph, the prostate is enlarged with foci of mineralisation, and there is a palisading periosteal reaction on the ventral aspect of L6 and L7.
What is the most likely diagnosis?
chevron_right Show answer and explanation
A. Benign prostatic hyperplasia
Benign hyperplasia is androgen-dependent: after castration the prostate involutes. A dog neutered years ago should not have it.
B. Prostatic neoplasia (carcinoma) with probable metastasis to medial iliac lymph nodes or lumbar vertebrae
Correct. In neutered dogs the prostate should be small: prostatomegaly and, above all, prostatic mineralisation are highly suggestive of neoplasia. The ventral periosteal reaction at L6–L7 suggests metastasis or regional spread.
C. Paraprostatic cysts of no clinical importance
Paraprostatic cysts may have mineralised walls, but they occur mainly in intact dogs and do not explain the vertebral periosteal reaction.
D. Acute bacterial prostatitis, which is the most common cause of mineralisation
Prostatitis is more common in intact dogs and rarely mineralises; in a neutered dog with mineralisation, neoplasia must be ruled out first.
lightbulb Key takeaway
Castration does not protect against prostatic carcinoma. In a neutered dog, any prostatomegaly or prostatic mineralisation requires neoplasia to be ruled out (ultrasound, cytology by wash or aspiration, thoracic staging). Always check the sublumbar lymph nodes and the ventral aspect of the last lumbar vertebrae.
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Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.