Table 5.2 Main prostatic disorders in old dogs.

  Hypertrophy Neoplasia Prostatitis
Average age 90% over 5 years 90% over 8 years chronic form
common in older dogs
Rectal palpation Bilateral enlargement
Often very large
Usually smooth surfaced
Often painful - but not in uncomplicated cases
Usually unilateral but may be bilateral
Not usually as large as hypertrophy
Usually firm and nodular
Treatment Oestrogen therapy - temporary regression
Prostatectomy - difficult but can be very successful (morbidity 30%, mortality 10%)
Antibiosis based on culture and sensitivity (erythromycin, trimethoprim,lincomycin and chloramphenicol achieve good tissue penetration)
?Surgical drainage and flushing
Other comments If oestrogen therapy does not induce regression - biopsy
An age-related hormonal imbalance has been suggested as the cause*
Must radiograph and/or use ultrasound to establish whether or not there is a local metastatis (e.g. to the pelvis) or widespread metastatis (e.g. to the lungs or liver) Attempts at surgical drainage can lead to pertionitis
Prostatic hypertrophy may predispose old dogs to develop prostatis

* Dihydrotestosterone accumulates in hypertrophic canine (and human) prostates and dihydrotesterone snd testosterone do not induce hvpertrophy whereas 3 a-androstanediol and 17b-estradiol (both secreted by the testis) do produce hypertrophy. Furthermore antioestrogen drugs (e.g. tamoxifen) or antiandrogens (e.g. cyproterone) cause glandular atrophy in both spontaneous and experimental canine prostatic hypertrophy.