Histopathology DiagnosticsHistopathology

Histopathology continues to be a powerful, yet inexpensive, part of veterinary diagnostics.

  1. Specimens should represent typical lesions, including active margins and adjacent (normal) tissue, rather than lesion cores or curetted debris. Autolysis, freezing, mutilation (forceps crushing or tearing), or removal of small samples by electrocautery will make samples unsuitable for proper evaluation.
  2. Specimens from different sites or types of lesions should be identified individually by size, suture tags, or separate containers. Samples thicker than 1/2 cm should be sliced to allow adequate fixation. Brain and eyes are exceptions; they should be fixed whole.
  3. Nearly all diagnostic histopathology can begin with tissue fixed in 10% buffered neutral formalin.
  4. Formula 
    37-40% formaldehyde100 ml
    distilled water900 ml
    sodium phosphate, monobasic4.0 gm
    sodium phosphate, dibasic6.5 gm

  5. Fixative volume should be 10-20 times specimen volume. After 12-24 hours, specimens can be transferred to just enough formalin to keep them moist during shipment. There is no need to pay for transport of excess fixative. Formalin will freeze at extremely low temperature, damaging the tissues. Adding 1 ml of ethanol to each 9 ml of 10% formalin will prevent such freezing.
  6. Wide-mouth bottles or Whirl-Paks are preferred containers. Narrow-mouth bottles often have to be broken or cut to release fixed tissues. Plastic bottles are better than glass; anticipate rough handling during shipment, and package accordingly. Most bottle lids will leak; if in doubt, tape the lid, or place the bottle and accession form in separate Whirl-Pak bags to avoid contamination or damage. Label container(s) adequately (owner, animal, veterinarian, site). Full interpretation of histopathologic findings hinges on complete clinical histories.
  7. Submit specimens from all major organs, including brain, if in doubt about which tissues to collect or if there are no gross lesions.
  8. Fresh tissue, handled gently and fixed adequately in 10% buffered neutral formalin will yield excellent results. Some pathologists, however, have advocated using Bouin's fixative for endometrial and endocrine specimens. The advantages, in our opinion, of Bouin's do not outweigh the disadvantages of extra reagents and processing steps. Tissues should be fixed in Bouin's no longer than 18 hours, as they become hard and brittle. Specimens must be washed 4-6 hours in several changes of alcohol to remove any picric acid (yellow), then stored/shipped in 70% alcohol. Over-fixation with Bouin's results in poor histologic staining.
  9. Cytologic examination of fluids, smears, or imprints is done by the Clinical Pathology Laboratory, Washington State University Veterinary Clinic, (509) 335-0745.
  10. Containers or formalin can be purchased from WADDL.
  11. Duplicate glass slides of specimens can be prepared for practitioner use and files. The cost of these slides is listed in the fee schedule.

Histology Slide Preparation

For those that only need slide preparation without interpretation, WADDL offers many staining and slide preparation options.

Turnaround times for slide preparation only cases depends upon the number of slides needed and our current caseload.

Instructions of how to submit samples: Samples need to be submitted fixed and placed in tissue cassettes. Paraffin blocks or pre-cut slides may also be submitted. Please fill out the accession form to be included with your samples. Samples can be mailed or dropped off at the WADDL office (Bustad 155N) or directly to the Histology lab, if submitting from another WSU department.

The shipping charge for the return of blocks & slides is $12.00 for within the State of Washington and $20.00 if sending to out-of-state.

Research cases have lower priority than diagnostic cases within the laboratory. Testing turn-around times expected for diagnostic cases do not necessarily apply to research work.

Samples for research projects should be fixed and submitted in tissue cassettes for processing.


Process and Embed (P&E)
Cutting fee (doesn't include stain cost.  See below for stain prices)
Frozen section: Cut unstained section per slide

Standard Stain

H&E Stain 4.00

Special Stains

Alcain Blue + PAS
Alcian Blue pH 1.0 & 2.5 & 0.4
Brown and Hopps Gram stain
Congo Red
Cresyl Echt Violet 8.00
Fite's Acid Fast
Fontana Masson
Giemsa 8.00
Hall's Bile Stain
Luxol Fast Blue
Masson's Trichrome
Melanin Bleach
Methyl Green Pyronin
Movat's Pentachrome25.00
Oil Red O8.00
PAMS-Periodic Acid-Methenamine Silver for Basement Membranes
Periodic acid schiff (PAS)
Perl's for Iron
Phosphotungstic Acid Hematoxylin (PTAH)
Rhodanine Method for Copper
Sudan Black B 8.00
Toluidine Blue 8.00
Trichrome, One Step 12.00
Urates, De Galantha's Method
Verhoff's Elastic Stain 8.00
Von Kossa for Calcium
Warthin Starry for Melanin
Warthin Starry (spirochetes) 8.00
Zeihl-Neelson's Acid Fast 8.50

Submission of Histology Research and Experimental Projects

Fill out the Accession Form Histology Research Services and bring it along with your samples to the WADDL Histology Section located on the 2nd floor in Bustad Hall, room 260.