Page 1377 - Clinical Small Animal Internal Medicine

147 Tumors of the Male Reproductive System 1315

2
0.7 mg/m IV once weekly for 3–6 treatments elicits a
VetBooks.ir complete response in over 90% of dogs. Other protocols
involving cyclophosphamide, vinblastine, doxorubicin,
and methotrexate have been used with less success.
However, for vincristine‐resistant tumors, doxorubicin
2
given at 30 mg/m IV every three weeks can be effective.
Radiation therapy is an effective treatment modality
for TVT. Orthovoltage radiation was evaluated in 18
dogs with solitary primary genital and cutaneous lesions.
All lesions were treated with a total dose of 10–30 Gy.
Seven dogs had a complete response to a single fraction
of 10 Gy. The remaining patients required an additional
2–3 fractions to achieve a complete response. In a sepa­
rate study, 15 dogs with primary genital TVT received
cobalt irradiation. A 100% complete response rate was
reported.
Figure 147.1 Fine needle aspirate of a canine TVT. Note the
homogeneous population of discrete round cells with mild Surgery can be used in cases of primary or metastatic
anisocytosis and anisokaryosis. The cells have a moderate amount lesions, but it is not typically recommended as the recur­
of cytoplasm with multiple discrete clear cytoplasmic vacuoles. rence rate can be up to 70%.
Lastly, the use of immunotherapy with intralesional
Any dog with suspected TVT should undergo full bacillus Calmette–Guérin (BCG) has been shown to be
staging, including urinalysis, as there is evidence that effective as a single agent and in combination with
dogs with TVT are at high risk of developing urinary vincristine therapy.
tract infections. Although metastatic disease occurs in
less than 10% of reported cases, evaluating for local Prognosis
metastasis with abdominal ultrasound and three‐view
thoracic radiographs is recommended. A differential for The prognosis for TVT is good to excellent as some dogs
suspected metastasis is transplantation (autologous or can experience spontaneous regression. The majority of
allogeneic) of TVT from the primary genital lesion. dogs that receive single‐agent vincristine therapy or radi­
ation therapy will be cured of their disease. The progno­
sis is, however, guarded for dogs that have ocular or
Therapy
central nervous system invasion or evidence of dissemi­
There are multiple treatment options for TVT. The least nated metastasis. An increase in the AgNOR area in the
invasive, least expensive and most effective option is nucleus was found to be a negative prognostic indicator
the use of single‐agent vincristine chemotherapy. Admin­ in dogs with TVT.
istering vincristine at the recommended dose of 0.5–

Further Reading

Ganguly B, Das U, Das AK. Canine transmissible venereal for carcinoma of the prostate in dogs. Int J Appl Res Vet
tumor: a review. Vet Compar Oncol 2016; 14(1): 1–12. Med 2013; 11(1): 16–24.
Grieco V, Riccardi E, Greppi GF, Teruzzi F, Iermanò V, Nødtvedt A, Gamlem H, Gunnes G, Grotmol T, Indrebø A,
Finazzi M. Canine testicular tumours: a study on 232 Moe L. Breed differences in the proportional morbidity
dogs. J Compar Pathol 2008; 138(2‐3): 86–9. of testicular tumours and distribution of histopathlogic
Hazzah T, Kass P, Brodsky E, et al. Evaluation of types in a population‐based canine cancer registry. Vet
mitoxantrone with piroxicam as first line chemotherapy Compar Oncol 2011; 9(1): 45–54.