What is the preferred method for diagnosing malignant tumors in small animals?

The preferred method for diagnosing malignant tumors in small animals is a biopsy. This technique involves obtaining a sample of tissue from the suspected tumor, which allows for histopathological examination. A biopsy provides definitive information about the presence of cancerous cells, as well as details about the type of tumor and its characteristics. This level of specificity is crucial for determining the appropriate treatment plan and prognosis.

While ultrasound and radiography are valuable imaging tools, and they can help in assessing the extent of a tumor or identifying abnormalities, they do not provide tissue samples. Consequently, these methods may only suggest the presence of a tumor but cannot confirm malignancy. Blood tests can offer supportive data regarding an animal's overall health and may indicate the presence of certain tumors indirectly (e.g., by evaluating tumor markers), but they are not sufficient for a definitive diagnosis of malignancy.

In summary, biopsy is the gold standard for accurately diagnosing malignant tumors due to its ability to provide detailed histological information critical for effective management and treatment planning.