|
Veterinary oncology, the study and treatment of cancer in companion animals, has become a growing practice in recent years. Prior to the past decade, veterinary options for therapeutic management of cancer in the dog were limited, and prognosis for such patients was often dismal. Today, new combinations of drugs (chemotherapy), improvements in surgical techniques for removing tumors, radiation therapy, and novel cancer-targeting drugs are successfully prolonging and improving quality-of-life in many dogs diagnosed with neoplastic disease.
The success of treatment to cure cancer lies in early detection of the disease (10 common signs ). However, early detection is often one of the most challenging aspects of this disease. This is primarily because not all cancers present as tumor masses on the surface of the body where they may be easily noticed and examined for changes.
Lymphoma
Lymphoma is a common form of cancer in dogs and cats. It is characterized by enlargement of one or many lymph nodes in the body. Lymphoma is a common cancer of dogs with remarkable breed predisposition. Lymphoma accounts for approximately 20 percent of all canine tumors, and >80 percent of cancers originating from blood cells.
The presentation of lymphoma is highly variable as lymphocytes can be found in virtually any organ in the body. Nonetheless, the most common form (referred to as stages) of lymphoma causes a non-painful enlargement of one or more lymph nodes that can be seen or felt from the body surface. Other forms of lymphoma can involve the liver, spleen, bone marrow and gastrointestinal tract, skin or nervous system (and other organs) and the clinical signs will reflect the organ system involved (e.g. vomiting or diarrhea with gastrointestinal forms; weakness or pale mucous membranes and others that reflect impaired production of blood cells from the bone marrow). Many dogs will simply feel ill (lose appetite, become lethargic) with any of the different forms.
Lymphoma is one of the most chemotherapy-responsive tumors seen in veterinary medicine, and most dogs tolerate chemotherapy very well with minimal impact on their quality of life. There is usually better than an 80% incidence rate of remission. Lymphoma is not a curable disease and remission checks must occur throughout the remainder of the animal's life. If disease reoccurs, a new round of treatment must be initiated (rescue therapy). The best outcome is seen with early detection.
Hemangiosarcoma
Hemangiosarcoma is a malignant, rapidly growing, highly invasive variety of cancer. It is a blood-fed sarcoma; that is, blood vessels grow directly into the tumor and it is typically filled with blood. A frequent cause of death is the rupturing of this tumor, causing the victim to rapidly bleed to death.
Hemangiosarcoma is somewhat common in dogs, estimated at 5% of new cancers per year, and more so in certain breeds of dogs including Labradors, German Shepherds and Golden Retrievers. It also occurs in cats, but is much rarer. Dogs with hemangiosarcoma rarely show clinical signs until the tumor has become very large and has metastasized. Typically, clinical signs are due to hypovolaemia after the tumor ruptures, causing extensive bleeding. Owners of the affected dogs often discover that the dog has hemangiosarcoma only after the dog collapses. The tumor most often appears on the spleen, right heart base, or liver, although varieties also appear on the skin or in other locations.
Prognosis of advanced hemgiosarcoma is poor. Typically dogs present to the veterinarian as if they have a ruptured spleen. Treatment includes chemotherapy and, where practical, removal of the tumor with the affected organ, such as with a splenectomy. If the spleen is ruptured then immediate surgery is required to save the animal. The best outcome is with early detection.
VDxI TK canine
VDxI TK CANINE measures Thymidine Kinase (TK) type 1 activity. TK is a salvage enzyme involved in the synthesis of DNA precursors and therefore only present in anticipation of cell division. The enzyme is not set free from cells undergoing normal division where the cells have a special mechanism to degrade the proteins no longer needed after the cell division. Hence, in normal dogs the amount of serum TK is very low. Tumor cells release the TK enzyme to the circulation, probably in connection with the disruption of dead or dying tumor cells.
Use of VDxI TK canine
VDxI TK has been found to be an effective diagnostic test for canine lymphoma and hemagiosarcoma. While TK is not specific to a particular type of cancer, positive values indicate neoplastic activity. The use of TK in conjunction with the clinical picture provides the veterinarian with a new powerful tool in cancer detection and management. LSA Detection:
• Data: Published studies demonstrate TK has a sensitivity of 0.92, a specificity of 0.98, with a false positive rate of only 1.9%. Furthermore, TK levels begin to rise in early stages and steadily increases with advanced disease. Node palpation may not detect more elusive cases and will not detect non-nodal LSA. • Use: TK provides a confirmatory test for elusive cases and non-nodal LSA.
Prognosis:
• Data: Pretreatment values of TK demonstrate a greater survival rate when values are below 30U/L. In a study of 44 dogs, the 50% survival time was 1 month for high TK (>30U/L) and 9 months for low TK (<30U/L). • Use: TK testing can assist in your communication with pet owners about life expectancy.
Monitoring:
• Data: Lymphoma responds quite well to chemotherapy, however disease recurrence is common. As patients enter remission, TK values drop to normal levels, and rises again upon relapse. • Use: Periodic monitoring of TK can provide early warning of disease recurrence. Recommended intervals are 4-6 weeks.
HSA Detection:
• Data: Recently completed studies pending publication demonstrate TK has a high sensitivity and specificity with a low false positive rate in detecting HSA upon discovery of a mass in organs such as spleen, liver and heart. • Use: TK assists in the rule-in that the identified mass is associated with hemangiosarcoma.
 |
