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Squamous metaplasia of the prostate in the dog

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Category: Schede
Hits: 10
  • Disciplina: Urologia
  • Specie: Cane

Squamous metaplasia of the prostate is a prostatic disorder that occurs in sexually intact dogs secondary to a state of excessively high levels of oestrogens of exogenous or endogenous provenance.1-6  The most important endogenous cause is a hormone-secreting Sertoli cell tumour. Independently of the cause, the hyperoestrogenism leads to stasis of secretions; this, together with the concomitant metaplasia, predisposes to the development of cysts, prostatitis and abscesses.7-9 Ectopia and cryptorchidism predispose indirectly to squamous metaplasia of the prostate.

 

CLINICAL FEATURES

Features compatible with a syndrome of feminisation of the male dog are a history of other male dogs showing sexual interest in the affected animal, the gradual appearance of bilateral, symmetrical alopecia, an increase in the volume of the mammary glands (gynaecomastia) and a pendulous prepuce. During the clinical examination it is important to inspect and palpate the testicles to exclude the presence of a cryptorchid or ectopic testis; the presence of bilateral atrophic testes is compatible with exogenous hyperoestrogenism while the presence of a single atrophied testis with a mass in the contralateral one is an indicator of endogenous hyperoestrogenism.

Transrectal palpation can detect enlargement of the prostate gland. Blood tests may show signs of oestrogen toxicity6 while numerous squamous cells may be found in the prostate fluid.

 

DIAGNOSIS

The definitive diagnosis can only be made from studying a biopsy sample. A presumptive diagnosis is based on the history (any treatment with oestrogens) or on the identification of a Sertoli cell tumour associated with prostatic enlargement.

 

TREATMENT

Depending on the source of the oestrogens, the treatment may be withdrawal of hormone therapy or castration. All the effects of oestrogens, except those on the bone marrow, are potentially reversible. In the case of stud dogs with a Sertoli cell tumour, unilateral castration is possible; however, a certain period of time is necessary before the normal hypothalamic-pituitary-gonadal axis is restored.

 

MONITORING THE PATIENT

Sterile prostatic cysts, if present, should be re-evaluated by ultrasonography about 1 month after treatment.

 

 

References

  1. Huggins C, Clark PJ:  “Quantitative studies of prostatic secretion: II. The effect of castration and of estrogen injection on the normal and on the hyperplastic prostate glands of dogs.” J Exp Med. 1940 Nov 30;72(6):747-62.
  2. Barrak ER. Berry SJ.: “DNA synthesis in the canine prostate: effects of androgen and estrogen tratment.”Prostate. 1987;10(1):45-56.
  3. Berg OA.: “Effect of stilboestrol on the prostate gland in normal puppies and adult dogs.” Acta Endocrinol (Copenh). 1958 Feb;27(2):155-69.
  4. MulliganRM.: “Femilization in Male Dogs: A syndrome associated with carcinoma of the testis and mimicked by the administration of estrogens.” Am J Pathol. 1944 Sep;20(5):865-75.
  5. O’Shea JD.: “Studies on the canine prostate gland. II. Prostatic neoplasm.”J Comp Pathol. 1963 Jul;73:244-52.
  6. Sherding RG, Wilson G 3rd, Kociba GJ.: “Bone marrow hypoplasia in eight dogs with Sertoli cell tumor.” J Am Vet Med Assoc. 1981 Mar 1;178(5):497-501.
  7. Jacobs G, Bersanti J, Prasse K, Selcer B.: “Colliculus seminali as a cause of a urethral filling defect in two dogs with Sertoli cell testicular neoplasm.”J Am Vet Med Assoc. 1988 Jun 15;192(12):1748-50.
  8. Lindberg R, Jonsson OJ, Kasstrom H.: “Sertoli cell tumours associated with feminization, prostatitis and squamous metaplasia of the renal tubular epithelium in a dog.” J Small Anim Pract. 1976 Jul;17(7):451-8.
  9. Spackman CJ, Roth L. “Prostatic cyst and concurrent Sertoli cell tumor in a dog.” J Am Vet Med Assoc. 1988 Apr 15;192(8):1096-8.

 

 

Suggested readings

  1. Ettinger SJ, Feldman EC. Textbook of Veterinary Internal Medicine. 6th edition. Elsevier-Saunders, St. Louis 2005.
  2. Couto CG, Nelson WR. Medicina Interna del Cane e del Gatto. Elsevier-Masson, 2010.
  3. BSAVA Manual of Canine and Feline Nephrology and Urology. 2nd edition. Editor: Johnathan Elliot and Gregory F. Grauer, 2007.
  4. OsborneCA, Finco DR. Canine and Feline Nephrology and Urology. Williams & Wilkins, Philadelphia, 1995