DWR Diagnostics Laboratory

Histopathology Sample Submission Guidelines

The following guidelines are recommended to ensure both the health and safety of submitting veterinary staff and those in the laboratory.

Following these guidelines will also ensure our laboratory technical team and pathologists have the required information to provide you with as useful a histopathology report as possible.

Please do not hesitate to contact the laboratory team with any questions at any time. 

We look forward to working with you and helping to provide the highest standard of care to your patients and clients. 

Turnaround Times

The vast majority of histopathology reports will be issued within 1-2 working days following receipt of a sample in the laboratory.

If samples require additional fixation or decalcification this will prolong the reporting time. We will endeavour to notify you if this is the case following receipt of the sample.

Sample Labelling

All sample pots should be clearly labelled and correspond with information provided on the submission form.

Minimum details on the sample pot should include the following:

  • Patients name and owners name or a patient identification number
  • The site/source of the sample.

Completion Of The Submission Form

A complete and thorough submission form will aid more appropriate interpretation of the sample by our pathologists, enabling us to provide you with more relevant and useful information.

Please ensure patient signalment and practice details are included in full in the boxes provided.

The submission form should also include the following where relevant:

  • Site/location of the sample provided
  • Macroscopic description of the lesion, including duration, progression, distribution
  • Any previous relevant pathology results. E.g., prior cytological diagnosis/ previous histopathology report
  • Any response to treatment
  • Appropriate adjunctive findings. E.g., imaging characteristics, particularly for bony or oral lesions
  • Any particular clinical questions can be included, or suspected differential diagnoses listed
  • Nature of the sample. E.g., endoscopic/ incisional/ excisional biopsy
  • If clinical photographs are available, these can be submitted to histology@dwr.co.uk.

Tissue Margin Assessment

  • Tissue margin assessment will be provided when appropriate and does not incur an additional fee
  • Please indicate the nature of the sample submitted (eg. incisional/excisional biopsy) to help determine when evaluation of tissue margins is appropriate
  • Tissue ink can be applied to a specimen on the surgical margins prior to fixation. To do this effectively blot the tissue dry, apply ink and blot the tissue again prior to placing in formalin. If possible, please avoid blue and red ink
  • If there are particular areas of concern regarding a tissue margin, these can be indicated by either placement of a suture or application of tissue ink. This will ensure assessment of the tissue in this region
  • Orientation of the tissue can be indicated prior to submission, either by suture application or tissue ink. Please identify two directions on the tissue. e.g. Cranial and dorsal
  • Please do not incise the tissue through a surgical cut margin to allow for accurate evaluation.

Fixation Guidelines

Samples for histopathological evaluation should be placed in 10% neutral buffered formalin as soon as possible after collection.

For optimum fixation a ratio of approximately 10:1 formalin to tissue should be used when practically possible.  

Tissue samples in formalin should NOT be refrigerated.


  • Ideally the entire intact lesion, with any adjacent normal tissue, should be submitted for evaluation
  • For larger samples, when the ratio of 10:1 formalin to tissue cannot be practically achieved, ensure the sample is fully covered by formalin which can later be replaced or added to following receipt in the laboratory
  • Larger samples can be partially incised (bread loafing technique), to a depth of 1cm, prior to submission to aid formalin penetration. Ensure the tissue remains in one piece to allow orientation. Avoid incising through surgical margins and instead slice through a visceral or epidermal surface. Photographs can also be taken prior to fixation
  • Hollow or tubular organs should be partially opened to allow for optimum formalin penetration
  • If preferable, large samples can be fixed in the practice for a period of 1-3 days, following which the sample can be sent to the laboratory covered in a formalin-moistened gauze swab.


  • Small samples, such as tru-cut biopsies, bone marrow cores or endoscopic biopsies, can be submitted in microcassettes, or cassettes and sponges, to prevent disintegration and loss of the sample(s) during transportation. Please contact the laboratory if you would like these provided.

Sample Packaging and Postage


Please submit histopathological samples in a receptacle appropriate for this purpose.

Pre-filled sample pots can be provided by the laboratory upon request to practices who utilise our courier service. Empty sample pots can be provided to those practices who send using alternative delivery systems.

The sample pot should be approved for the use of formalin, shatterproof and of adequate size to allow for the appropriate volumes of formalin and tissue. Tissue should, at the minimum, be fully covered by formalin and free floating/moveable in the pot.

  • Lesions from separate sites or with clinically distinguishable features should be submitted in separate and individually identified pots
  • Do not use narrow necked pots as tissue may not be easily removed following fixation
  • Please do not use pots with lockable lids (e.g. sharps containers) as it may not be possible to safely remove the sample following receipt in the laboratory
  • Lids should be completely sealed and leakproof to prevent spillage of formalin.

Pots of varying sizes (60mL, 250mL, 1L, 2.5L) can be provided by the laboratory, please contact the laboratory if you would like to request these.


The receptacle containing the tissue specimen (either pre-fixed or in formalin) should be placed in a secondary completely sealed, shatterproof and leak proof bag or container, containing sufficient absorbent material for the volume of formalin.

  • Samples from separate patients should be packaged separately
  • The submission form should be placed outside of the container and bag to prevent contamination
  • Cytological samples/slides should be packaged separately to prevent exposure to formalin forms.


Diagnostic histopathology samples are typically categorised as Biological Substances, Category B or Exempt Biological Samples.

It is advised that samples are submitted in outer packaging labelled with ‘UN3373’. This is indicated on our self-addressed postage bags and postage labels.

Packaging should comply with P650 packaging regulations.

General Enquiries

For any queries related to the submission of histopathology samples please contact the laboratory.

Email: lab@dwr.co.uk or histology@dwr.co.uk

Telephone: 01638 572900