Ford W. Bell

Prostatic intraepithelial neoplasia in dogs with spontaneous prostate cancer

Prostatic intraepithelial neoplasia (PIN) is the most likely precursor of human prostate cancer. The prevalence and immunophenotype of PIN in dogs with spontaneous prostate cancer has not been previously described. To investigate the association between PIN and prostate cancer, we evaluated the prostates of dogs with spontaneous prostate carcinoma. The prevalence of PIN was determined in formalin‐fixed prostates from 29 dogs with spontaneous prostate cancer. Using immunoperoxidase techniques, we compared basal cell layer integrity (high molecular weight keratin 34 beta‐E12), proliferative index (MIB‐1), and microvessel density (Factor VIII‐related antigen) in 14 prostates which contained benign epithelium, PIN, and carcinoma. PIN was present in 19 of 29 (66%) prostates from dogs with spontaneous prostate cancer. The basal cell layer was intact in benign epithelium, disrupted in 72% of acini with PIN, and absent in carcinoma. The mean proliferative index was 17%, 25%, and 40% for benign epithelium, PIN, and carcinoma, respectively, and these differences were significant. The mean microvessel density in foci of PIN and carcinoma (32 and 39 vessels per mm2, respectively) was greater than in benign epithelium (23 vessels per mm2). High‐grade PIN is common in the prostates of dogs with spontaneous carcinoma. The basal cell layer is partially disrupted in PIN, whereas it is absent in prostate cancer. The proliferative index and microvessel density of PIN are intermediate between benign epithelium and cancer. These results are similar to those reported for human PIN and prostate cancer, and indicate that PIN is part of a morphologic continuum in the progression of prostate cancer. To our knowledge, this is the first description of high‐grade PIN spontaneously occurring in animals. The canine prostate may serve as a useful model for examining factors that modulate PIN and prostate cancer progression. Prostate 30:92–97, 1997.

Prostatic Hemangiosarcoma in a Dog: Clinical and Pathologic Findings:

Prostatic hemangiosarcoma (HS) appears to be rare in the dog. In 3 of 4 previously reported cases, the prostate was involved via metastasis. For 1 dog, the primary tumor presumably was located in the prostate gland, but no details were given. The present report documents what we believe is a primary HS of the prostate in a dog that presented with clinical signs of urinary tract disease. The prostate tumor and metastases had microscopic features of a poorly differentiated HS, and the diagnosis was confirmed by immunohistochemistry. An 11-year-old male Miniature poodle was admitted to a veterinary hospital because of straining to urinate and defecate and passing “ribbon-like” feces for approximately 1 month. Physical examination revealed prostatomegaly. The dog was castrated and given an injection of 0.25 mg of estradiol cypionate intramuscularly. Clinical signs persisted, and the dog was referred to the University of Minnesota Veterinary Teaching Hospital (UMVTH) 6 days after castration. Physical examination revealed a thin dog with prostatomegaly and a very distended urinary bladder. A complete blood count revealed a normochromic normocytic anemia (PCV = 23%, normal > 37%) without significant regenerative response. The dog was catheterized without difficulty, and 225 ml of yellow urine were removed. A urinalysis was consistent with urinary tract infection, and a urine culture revealed Klebsiella pneumoniae and Proteus mirabilis (> 10 colony forming units/ml). Prostatomegaly was identified on abdominal radiographs. A sonogram revealed diffuse prostatic hyperechogenicity with irregular multifocal hypoechoic masses. A prostatic biopsy was performed with a Tru-Cut biopsy needle via a perineal approach. Microscopic examination revealed neoplastic polyhedral and spindle cells of uncertain tissue type. Following a course of radiation therapy, which failed to shrink the prostate, the dog was euthanized. At necropsy, the prostate gland protruded from the cranial rim of the pelvis and was tightly adhered to the pelvic canal, especially on the right side. Although both lobes of the prostate were enlarged, the right lobe was more severely affected. The prostate was 10.5 x 6.0 x 4.0 cm and weighed 125 g. Transverse sections of the prostate revealed a large yellow core encircled by a rim of red tissue. Reddish-yellow tissue was present within the right obturator foramen. Soft red and white nodules 0.7 cm and 4 cm in diameter were found in the left and right medial thigh muscles, respectively.

Canine Distal Renal Tubular Acidosis and Urolithiasis

Distal RTA is characterized by decreased distal renal tubular hydrogen ion secretion, decreased ability to acidify urine, hypercalciuria, hyperphosphaturia, hypocitraturia, and metabolic acidosis. Because of the resulting alterations in urine composition and pH, patients with distal RTA are predisposed to urolithiasis and renal calcification. Diagnosis of distal RTA is important because it is a potentially reversible disorder that, left untreated, may cause nephrocalcinosis, recurrent urolith formation, moderate to severe metabolic acidosis, and renal failure.

Neoplastic diseases of the thorax.

Thoracic neoplasia comprises a heterogeneous group of diseases, many of which are distinctly uncommon in veterinary medicine. These diseases often present the clinician with diagnostic and therapeutic challenges. Careful diagnostic work-up and staging are essential for consideration of therapeutic options and formulation of prognosis. Neoplastic diseases of the thorax are classified here as tracheal tumors, primary lung tumors, nonrespiratory intrathoracic tumors, and thoracic wall tumors.