Page 1374 - Clinical Small Animal Internal Medicine

1312 Section 11 Oncologic Disease

The metastatic rate for seminomas and Sertoli tumors cell carcinoma, undifferentiated carcinoma, and sarco­
VetBooks.ir is approximately 10%. Metastasis occurs through lym­ mas are rarely found. In dogs, most prostatic carcinomas
are suspected to be ductal or urothelial in origin, rather
phatic invasion. Therefore, evaluation for regional
metastasis is warranted prior to surgery. There are
receptors in ductal epithelial cells suggests that canine
reports of aggressive seminomas in dogs with distant than acinar, as in humans. The absence of androgen
metastasis to the spleen, lungs, meninges, eyes, and skin. prostatic carcinoma formation is likely androgen inde­
Testicular ultrasound is recommended in dogs with clin­ pendent. Controversy still exists regarding the effects of
ical signs of testicular neoplasia and nonpalpable disease. castration on the development of canine prostatic
For dogs with signs of feminization, obtaining serum lev­ carcinoma. Regardless, three studies did reveal that cas­
els of estradiol‐17‐beta may help support a diagnosis of trated dogs were at increased risk for developing prostatic
functional testicular tumor. Paraneoplastic hypertrophic carcinoma with odds ratios ranging from 3.86 to 4.34.
osteopathy, although rare, has been reported in a dog
with a Sertoli cell tumor. Therefore, extremity radio­ Epidemiology
graphs should be performed in dogs with Sertoli cell
tumors with concomitant lameness. Prostate tumors are rare neoplasms in dogs, having a
prevalence of less than 1% of all canine cancers. These
tumors are extremely uncommon in cats with only a few
Therapy reported cases.
Castration, including scrotal ablation, is considered the
treatment of choice for testicular tumors and is curative Signalment
for dogs with nonmetastatic disease. However, when
metastatic disease is present, adjunctive chemotherapy There is no known breed predilection and prostatic car­
or radiation therapy is necessary. The use of cesium‐137 cinoma typically affects older dogs, median age 10 years.
external beam radiation therapy for regional lymph node Although exceedingly rare, prostatic carcinoma can
metastasis in four dogs with seminoma has been occur in older cats.
described and shown to be 100% effective. There is lim­
ited information regarding the usefulness of chemother­ History and Clinical Signs
apy, but there is suggested efficacy with both cisplatin
and bleomycin. There is recent evidence that seminomas The most common presenting clinical sign in a dog with
and Leydig cell tumors express kit (CD117), making the a prostate tumor is either tenesmus or dysuria, including
use of a tyrosine kinase inhibitor (such as Palladia™, or hematuria, stranguria or pollakiuria. Older, castrated,
Gleevec®) a reasonable treatment option for cases with male dogs presenting with any of the above clinical signs
metastatic disease. The use of metronomic chemother­ should be evaluated for urogenital cancer as few other
apy for high‐grade seminomas is also a valid treatment diseases cause such signs. Other possible presenting
option, as one study found that seminomas demon­ signs are anorexia, weight loss, acute lameness or back
strated increased angiogenesis. pain which may indicate metastasis to the pelvis or lum­
bar spine.
In cats, clinical signs vary but include dysuria, urethral
Prognosis obstruction, and obstipation. Physical exam findings and
The prognosis is excellent for nonmetastatic testicular diagnostics are similar to those for prostate tumors in
tumors and guarded for metastatic tumors or dogs that dogs.
have blood dyscrasia secondary to hyperestrogenism.
Also, seminomas with high mitotic index and increased Diagnosis
numbers of agyrophilic nucleolar organizer regions
(AgNORs) had increased risk of metastasis. Physical exam findings are variable but the most com­
mon abnormality is prostatomegaly that can be palpated
as irregular, firm, and painful and/or demonstrates loss of
Prostate Tumors the median raphe. Complete blood count and serum bio­
chemistry rarely reveal any specific changes. Urinalysis
often indicates pyuria or bacteriuria as secondary bacte­
Etiology/Pathophysiology
rial infection is commonly associated with this neoplasia.
Carcinomas are the most common prostatic tumor, with Many owners report improvement of clinical signs if
transitional cell carcinoma and adenocarcinoma being treated with antibiotic therapy, but this improvement is
the most frequent types. Other types such as squamous often short‐lived. Three‐view thoracic radiographs are