Page 1645 - Cote clinical veterinary advisor dogs and cats 4th

Prostatic Neoplasia 829

RISK FACTORS with a large, irregular prostate on rectal exam. • Reports describing definitive therapy for dogs
The effects of reproductive status on the Castrated dogs with radiographic and/or with localized prostate tumors are limited.
VetBooks.ir understood. Exposure to endogenous androgens very likely to have prostatic neoplasia. Intact ○ External beam radiotherapy to prostate Diseases and Disorders
ultrasonographic prostatic mineralization are
The following treatments can be considered:
development of prostate tumors are not fully
± regional lymph nodes
dogs are unlikely to have prostatic neoplasia
has been associated with development of
prostatic adenocarcinoma in dogs. Castration
the urethra (animals with focal prostatic
of prostatic neoplasia requires cytologic or
at a young age appears to increase the risk of if no mineralization is found. Confirmation ○ Partial prostatectomy with preservation of
other types of prostate tumors. histopathologic evaluation. lesions)
○ Complete prostatectomy with urethral
ASSOCIATED DISORDERS Differential Diagnosis resection/permanent cystostomy tube
Secondary bacterial cystitis (p. 232) • Other prostatic disorders (largely limited to placement
intact dogs) ○ Given the high metastatic rate, chemo-
Clinical Presentation ○ Benign prostatic hyperplasia (BPH) therapy (e.g., doxorubicin, mitoxantrone,
DISEASE FORMS/SUBTYPES ○ Paraprostatic cyst carboplatin, cisplatin) is indicated in
Histologic types include adenocarcinoma, ○ Prostatic abscess definitively treated animals. The efficacy
urothelial carcinoma (i.e., prostatic exten- ○ Prostatitis of chemotherapy has not been established
sion of urethral transitional cell carcinoma), • Locally invasive transitional cell tumor of conclusively.
and undifferentiated carcinoma. The natural the urinary bladder ○ COX2 inhibition with piroxicam 0.3 mg/
behavior of and diagnostic approach to each kg PO q 24-48h (or possibly other selec-
subtype are identical. Initial Database tive COX2 inhibitors) can be beneficial in
• CBC, serum biochemistry profile, urinalysis, animals with prostatic adenocarcinoma or
HISTORY, CHIEF COMPLAINT ± urine culture. Midstream catch or cath- prostatic carcinoma of urothelial origin.
Clinical signs are often chronic, linked to the eterized (culture) samples preferred; avoid
urinary tract, and most commonly include cystocentesis Chronic Treatment
hematuria, incontinence, and stranguria. Rarely, • Thoracic and abdominal radiographs Palliative therapy:
patients may present with complete urethral (including evaluation of bony structures • Palliative care should be considered in
obstruction. Animals with large masses may for metastasis; sublumbar lymph node) animals with metastatic disease and those
present with tenesmus and/or altered stool shape • Abdominal ultrasound (see Videos) with advanced localized disease not amenable
(flattened stools) caused by compression of the • Aspirates of regional lymph nodes if indicated to definitive therapy. The efficacy of pal-
colon by the tumor. Local invasion into the to identify the presence of metastatic disease liative treatments has not been established
lumbar vertebrae or bone metastasis may cause conclusively.
signs of pain and/or lameness. Advanced or Confirmatory Testing • Palliative radiotherapy may provide short-
• Cytologic evaluation of a prostatic aspirate term relief from urinary obstruction or
PHYSICAL EXAM FINDINGS or wash may aid in establishing a diagnosis other clinical signs resulting from local
External physical exam is often unremarkable. A (p. 1153). Transdermal aspiration or biopsy disease.
large, irregular mass that may be firmly adhered of the prostate may be associated with a • Placement of a urethral stent may provide
to surrounding pelvic structures is typically risk of tumor seeding. However, the need similar short-term relief from obstruction.
found on rectal palpation. Animals with bone to establish a definitive diagnosis usually • Permanent cystostomy tube placement/
metastases may display evidence of pain during supersedes the risk. urinary bladder marsupialization may provide
orthopedic exam of the spine, pelvis, and/or • Histopathologic confirmation should be relief from urinary obstruction.
hindlimbs (p. 1143). The sublumbar lymph obtained before a patient undergoes defini- • Electrosurgical transurethral resection may
node may be enlarged. tive therapy. Traumatic catheterization under result in significant palliation of clinical signs.
ultrasound guidance or digital palpation from • Castration may provide alleviation of signs
Etiology and Pathophysiology the rectum is useful to obtain sample for in intact dogs with concurrent prostatic
Intact and castrated dogs develop prostatic cytologic and histopathologic evaluation hyperplasia.
carcinoma. Tumor location often precludes early with minimal risk of urethral obstruction • Systemic treatment with chemotherapy and/
diagnosis; most tumors are consequently locally or tumor seeding. or piroxicam
advanced and have metastasized (70%-80%) • CT for surgical or radiation treatment • Use of stool softeners may be helpful in dogs
at the time of diagnosis: planning. with tenesmus.
• The ultimate metastatic rate for prostate • Detection of BRAF mutation in urine DNA
tumors is 85%-100%. may be helpful for making a diagnosis of Drug Interactions
• The most common sites for metastasis include canine urothelial and prostatic carcinoma Patients receiving piroxicam therapy should not
lungs (50%), lymph node (>30%), and bone (https://www.sentinelbiomedical.com/ be given corticosteroids or other nonsteroidal
(15%-45%). The pelvis and lumbosacral braf-vets/). antiinflammatory medications.
spine are the most common sites of bony
metastasis. TREATMENT Possible Complications
Cyclooxygenase 2 (COX2) expression may play Potential complications of chemotherapy
a role in tumor development and progression Treatment Overview (e.g., gastrointestinal toxicity, bone marrow
because 75% of prostatic carcinomas have been Long-term disease control is the ultimate goal suppression) and radiation treatment (e.g.,
shown to express COX2 protein, whereas such but is often not possible due to extensive local tissue irritation) are similar to those observed
expression is not evident in normal prostatic or metastatic disease. For patients with lesions for other tumors. Piroxicam therapy may be
tissue. not amenable to definitive therapy, palliation associated with gastrointestinal ulceration and
of clinical signs is the primary goal. kidney injury.
DIAGNOSIS
Acute General Treatment Recommended Monitoring
Diagnostic Overview Definitive therapy: After treatment, recommended monitoring
The diagnosis is suspected based on the pres- • Curative therapy should be considered only includes routine physical exam, abdominal
ence of lower urinary tract signs in a patient for dogs with no evidence of metastases. ultrasound, and thoracic radiographs. For

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