Diagnosing Cancer in Pets
The diagnosis of cancer is not always as straightforward as it would seem. Some animals may exhibit clinical signs for months before the actual cancer can be found. However, several methods are available that can be used to pinpoint and diagnose neoplastic disease in pets:
1. Physical examination.
Many tumors can be diagnosed on physical examination alone using visual observation and/or manual palpation.
2. Radiography (X rays).
Both plain films and contrast techniques can be used to demonstrate tumors of the lung, gastrointestinal tract, bladder, and other internal organs. Sometimes a radiograph can be pathognomonic (completely typical) for a particular type of tumor, as in the case of bone tumors. Multiple nodular masses in the lung would suggest bloodborne metastasis of a malignant tumor somewhere else in the body. However, in most cases, a tumor visualized on a radiograph must be biopsied to rule in or rule out malignancy.
3. Ultrasonography.
The use of ultrasonic waves to visualize structures within the body is commonplace in modern veterinary medicine, and is a valuable tool for diagnosing internal cancers. Ultrasound is a very reliable method to help differentiate tumors from benign cysts. It is also useful in evaluating the sizes of internal organs. One area in which ultrasonography is not of much value is in the evaluation of the lungs, since ultrasound waves cannot effectively pass through air-filled structures.
4. Cytology.
Examination of cells pulled from body cavities, mammary gland secretions, nasal exudates, respiratory secretions, bone marrow, lymph nodes, or various “lumps and bumps” is a popular method of diagnosing neoplastic disease. Cytological examinations are especially effective in ruling out other causes of lumps and bumps, including abscesses, cysts, and granulomas.
5. Biopsy.
Biopsy is the most common and the most definitive way to make the diagnosis of cancer in animals. Gross and microscopic examination of a neoplasm by a competent veterinary pathologist can be expected to yield an accurate diagnosis 90 percent of the time. Mis diagnosis can occur if the sample of tissue submitted is too small or if an area of the tumor that was selected for biopsy does not contain viable cells. For example, osteosarcoma is frequently misdiagnosed because these tumors contain a great deal of dead tissue and reactive fibrous tissue. If these “benign” areas of the tumor are inadvertently biopsied, the pathologist will not find malignant cells.
6. Endoscopy or laparoscopy.
Fiberoptic endoscopes are valuable diagnostic tools in the fight against cancer. With these instruments, tumors in the esophagus, stomach, bronchi, liver, spleen, and other organs can be visualized without dangerous exploratory surgery. Biopsies of tumors can also be obtained with these instruments.
7. Nuclear medicine.
Nuclear scans of the liver, thyroid, lung, spleen, kidney, and bone are used in veterinary colleges and highly specialized veterinary hospitals to diagnose cancer. Radioisotopes with short half-lives are used, and anesthesia of the pet is rarely required. These scans have few adverse effects on the pet.
8. Blood tests.
The diagnosis of certain types of neoplastic disease can be assisted by results obtained through the microscopic and biochemical analysis of a pet’s blood. For example, an increase in serum cholesterol and the enzyme alkaline phosphatase is typically found in canine Cushing’s disease, which is caused by a tumor of the adrenal gland or pituitary gland. Similarly, cancer of the bone marrow (leukemia) can be diagnosed by finding tumor cells in the bloodstream. Finally, specific blood tests can be used to confirm or discount suspected cases of feline leukemia or feline immunodeficiency virus infections in sick cats.
( source vet-zone )
0 comments:
Subscribe to:
Post Comments (Atom)
