Histopathology

Fix specimens in 10% buffered formalin and submit in wide-mouth, leak-proof containers or double-bagged, leak-proof, sealed plastic bags. Tissues must be fixed immediately following collection. Place 5 mm thin tissues (1/4 inch or about the thickness of a wooden pencil) in 10% formalin. The ratio of tissue to formalin should be 1 volume tissue to 10 volumes of formalin. Neutral buffered formalin is available from commercial sources. Do not freeze formalin-fixed tissues, as the tissue will be sufficiently damaged to preclude critical histopathological examination.

Label containers (not the lids) with names of veterinarian, owner, and animal. This allows clinic and laboratory personnel to verify specimen identity. Improper handling or fixation of tissue can induce artifacts that may result in nondiagnostic or unsuitable specimens.

Provide a complete history and summary of surgical or necropsy findings. When submitting multiple tumors, package them individually and note each tumor location. For tissues other than tumors, one container may be used.

Practitioner necropsy. The clinical history and findings can help to target tissues for histopathologic examination. In cases with no history or sudden death, a complete set of tissues should be collected. When in doubt as to which specimens and tissues to collect, please call the laboratory. The following is a guide to routine tissue collection during necropsy.

• Bacteriology and Virology: fresh liver, kidney, lung, spleen, large and small intestine (ligated segments), and brain. Keep refrigerated and ship with cold packs.
• Histopathology:  affected tissues with lesions, brain, heart, lung, liver, spleen, kidney, stomach, small intestine, large intestine, lymph node, urinary bladder, skeletal muscle, bone marrow and thymus on young animals. Fix tissue in neutral-buffered formalin.
• Toxicology:  stomach content, liver and kidney. Keep refrigerated and ship with cold packs.

See additional information under related sections, and refer to shipping instructions.

Dermatologic cases.  Skin biopsies should be obtained from multiple sites. Pertinent history should be submitted including results from any prior antibiotic or corticosteroid therapy, endocrine assays, skin scrapes and any other clinical data. The distribution of lesions should be drawn on the figure included on the biopsy form.