Your pet's general health status is assessed to identify disease which may adversely affect prognosis, and limit or alter therapy. After a thorough physical examination the screening laboratory evaluation generally includes a complete blood cell count, serum biochemistry panel, and urinalysis. Other general diagnostic tests are performed as indicated. Survey radiographs are indicated to detect metastasis, determine potential bone involvement, evaluate orthopedic soundness prior to amputation or limb-sparing in dogs with osteosarcoma, localize oral or nasal masses, etc. Contrast radiographic studies can determine the extent of gastrointestinal and genitourinary neoplasia. Computed axial tomographic (CAT) scanning or magnetic resonance imaging (MR) are becoming more available and defines the invasive characteristics of deep seated tumors much more clearly than survey radiographs.
CAT or MR imaging procedures are particularly helpful when planning involved surgical procedures. Ultrasonography can be used to determine the proximity of a tumor to large blood vessels, to determine the cystic nature of masses, to evaluate possible intra-abdominal metastases to lymph nodes or organs, and to assess the initial and post-treatment tumor volume.
DIAGNOSIS: The diagnostic plan for a suspected tumor involves the clinical evaluation described above as well as characterizing the tumor, the surrounding area and the rest of the body where cancer may have spread with x-rays, ultrasound or other imaging. The keystone of the diagnosis is a cytologic or histologic confirmation of malignancy.
CYTOLOGIC ASSESSMENT: Cytologic examinations of bone marrow aspirates, buffy coat preparations of peripheral blood samples and fine needle aspiration biopsies of accessible tumors and regional lymph nodes are important diagnostic procedures. Fine needle aspiration can be accomplished on any accessible mass. Often, a rapid, inexpensive diagnosis can be made for certain tumor types (lipomas, sebaceous adenomas, mast cell tumors). However, cytologic evaluation of fine needle aspirates or bone marrow specimens must not be over-interpreted. Treatment decisions should be based on a cytologic diagnosis only when a definitive diagnosis can be made such as with lymphosarcoma, mast cell tumors, etc.
TUMOR BIOPSY: Many techniques are available for tissue biopsy. The method selected should safely and simply procure adequate tissue samples to provide an accurate diagnosis without compromising treatment. Biopsies can be excisional (complete removal of the tumor) or nonexcisional (removal of only a portion of the tumor). Nonexcisional techniques include: a) cytology from a fine-needle aspirate, brush samples, impression smears or effusions, b) histopathology of cutting forcep biopsies, cutting needle biopsies, punch biopsies, and incisional biopsies. continued