This prostate disease predominantly affects dogs1. The presence of a cyst of prostatic origin has been reported in one cat, whereas there are several reports of cysts deriving from Muller’s ducts (‘male uterus’).
PATHOGENESIS
Paraprostatic cysts are one or more encapsulated fluid collections which are found near the prostate, sometimes connected to it by a duct (patent or not) or adhesions. Most of these cysts do not communicate with the urethra.
The cysts can derive from the vestigial male uterus (Muller’s ducts) or directly from the prostate as a consequence of enlargement of an already existing cyst due to prostatic retention. In the former case the rest of the gland is normal, whereas in the latter, there is usually benign cystic hyperplasia. These cysts can differ greatly, with their walls being thin or thick and calcified or smooth.
CLINICAL ASPECTS
Depending on their size, paraprostatic cysts can compress the urethra or colon, causing tenesmus. The reported clinical signs include incontinence since partial obstruction of the urethra can lead to over-distension of the bladder. When particularly large cysts are present, there may be abdominal distension or swelling of the perineal region (perineococele).
Urinalysis is often normal, except for haematuria which can be present as a consequence of bleeding of a cyst communicating with the urethra; sometimes concomitant infections of the lower urinary tract may be found and, in these cases, the cysts are often infected. The contents of the cyst can by aspirated under ultrasound guidance and are usually sterile and serous, ranging from yellowish to blood-stained in colour. Radiographically two structures compatible with the bladder can be seen and cystography may be necessary to determine which of the two is the bladder and which is the cyst.
DIAGNOSIS
To make the diagnosis an exploratory laparotomy, with drainage of the cysts and excisional biopsy, is usually indicated.
TREATMENT
The treatment of choice is surgical excision; in those cases in which the cysts cannot be excised completely, omentalization is recommended. Contemporaneous orchidectomy is advised.
MONITORING THE PATIENT
The caudal part of the abdomen must be assessed by ultrasonography for several months.
Suggested readings
- Ettinger SJ, Feldman EC: “Textbook of Veterinary Internal Medicine, 6th edn”. Elsevier-Saunders, St. Louis 2005.
- Couto CG, Nelson WR: “Medicina interna del cane e del gatto”
- Elservier-Masson, 2010.
- BSAVA Manual of Canine and Feline Nephrology and Urology Second edition, Edited by Johnathan Elliot and Gregory F. Grauer, 2007.
- OsborneCA, Finco DR: Canine and feline nephrology and urology. Williams & Wilkins, Philadelphia, 1995
References
- Black GM, Ling GV, Nyland TG, Baker T.: “Prevalence of prostatic cysts in adult, large-breed dogs.”J Am Anim Hosp Assoc. 1998 Mar-Apr;34(2):177-80.