How to detect a tumor in a rat? - briefly
Apply non‑invasive imaging (high‑resolution ultrasound or MRI) together with manual palpation under anesthesia, then verify any suspect mass by biopsy and histopathological examination.
How to detect a tumor in a rat? - in detail
Detecting neoplastic lesions in laboratory rats requires a systematic approach that combines visual inspection, imaging, and histopathological confirmation.
First, perform a thorough physical examination. Palpate the abdomen, subcutaneous tissues, and any accessible organ surfaces. Record any masses, asymmetry, or skin changes. Document size, consistency, mobility, and tenderness.
Second, apply non‑invasive imaging techniques:
- Ultrasound – high‑frequency probes (30–40 MHz) provide real‑time images of soft‑tissue masses; measure dimensions and vascular flow with Doppler.
- Magnetic Resonance Imaging (MRI) – T1‑ and T2‑weighted sequences differentiate tumor tissue from surrounding structures; contrast agents (gadolinium) enhance vascular lesions.
- Computed Tomography (CT) – thin‑slice scans identify calcifications, bone involvement, and lung metastases; intravenous iodine contrast improves soft‑tissue contrast.
Third, collect biological samples:
- Blood – assess complete blood count, serum chemistry, and tumor markers (e.g., carcinoembryonic antigen, alpha‑fetoprotein) relevant to the suspected tumor type.
- Urine – screen for metabolic by‑products that may indicate renal or bladder neoplasia.
Fourth, obtain tissue for definitive diagnosis:
- Perform a surgical or needle biopsy under aseptic conditions. Use a 16‑gauge core needle for solid tumors; excise the entire lesion when feasible.
- Fix specimens in 10 % neutral‑buffered formalin, embed in paraffin, and cut 4‑µm sections.
- Stain with hematoxylin‑eosin for morphological assessment.
- Apply immunohistochemical panels tailored to the tumor lineage (e.g., cytokeratin for epithelial tumors, vimentin for mesenchymal, Ki‑67 for proliferative index).
Finally, integrate data:
- Correlate imaging dimensions with palpation findings.
- Compare histopathology with clinical signs and laboratory results.
- Classify the tumor according to the International Agency for Research on Cancer (IARC) guidelines for rodent neoplasms.
Adhering to this protocol ensures accurate detection, characterization, and documentation of tumors in rat models, supporting reliable experimental outcomes.