Preparing Specimens


Small specimens

  • Place specimen in small jar filled 1/2 to 3/4 full with formalin​ (10% NBF)
  • Ideal amount of formalin is 10:1
    • 10 times the volume of formalin as the sample
  • Small samples are ready for shipping immediately. Formalin fixation occurs at a rate of 1 mm per hr for the first hr, and then slows to about 1 mm every 3 hours. A 1 cm thick tissue will fix completely in 12 hours in the correct volume of formalin.
  • Specimens should be no larger than 2-3 cm
  • Ensure the formalin jar is filled 1/2 to 3/4 full

Large specimens​​

  • Spleen, liver lobe etc​
  • Fix in 10% NBF; it is a good idea to obtain a supply for large samples (see here:
  • 10% NBF at 10:1 formalin:tissue  
  • Blood filled specimens fix more slowly
  • In general over night fixation is adequate for shipping purposes; in general large specimens take 1-2 weeks to fix completely
  • Include a small amount of formalin in the primary container with the sample


  • Makes sure all lids are leak proof​
  • Enclose cytology slides in air tight packaging if submitted with biopsies, because formalin vapors can cause artifacts in cytology smears.


  • In extreme cold specimens can freeze during transport​
  • To prevent artifacts that can occur through freezing a tissue we recommend that ethanol, or isopropyl alcohol (rubbing alcohol) be added to the formalin
  • Add 1 part alcohol to 9 parts formalin
  • For our standard 90ml jars which contain 50ml of formalin, this amounts to adding about 5.5 ml of alcohol


Aspirates/ Smears

  • Please (if possible) use glass slides with frosted ends so that information can be written on the slide. Even if you do not have frosted slides, use a permanent marker to identify the slides with owner and/or pet name as well as location (especially if more than one location is aspirated).
  • Slides from aspirates or smears should be submitted in plastic slide holders (which we will provide) to prevent breakage during transit.
  • If cytology preparations are submitted in the same package as formalin fixed tissue, please double bag the samples to prevent staining artifact on the slides.


  • Fluids should be sent in lavender/purple top tube (EDTA) and red top tube (no anticoagulant). They should be secured during shipping with packing (bubble wrap or paper towels) to prevent breakage. In very hot weather, a cold pack will prevent deterioration of the cells.
  • Please label tubes with owner/patient as well a source.
  • If possible, direct smears should be prepared from the fluid before shipping.


  • Cytology submissions can be shipped in your own packaging. It is not necessary to use the FedEx Clinical Pak. The billable stamp that we provide you for free shipping can be used on any box. Your FedEx driver can provide you with additional shipping materials if you need them.



  • All samples must be submitted in a primary and secondary container
    • Example: Formalin jar placed into plastic transport pack​
    • Example: Garbage bag sealed containing specimen, placed in plastic jar/bucket
  • Absorbent material must be placed within secondary container or around formalin jar
  • Small formalin filled sample jars and larger jars are available at no charge
  • Sample packs are available at no charge
  • Call with any questions 845-687-2850

Improperly packaged specimens may be subject to fines by FedEx and are the responsibility of the client

Things to avoid:

  • Plastic food containers: Even with tape these warp, bend, and leak. 
  • Glass containers: These are subject to breaking.
  • Single ziplock bags- multiple bags are needed because one will usually leak.

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