Submission Tips

Packaging Samples | Submission Details | Fixative | Skin | Biopsies | Auto-immune Skin Disease | Gut | Brain (and spinal cord) | Eyes | Tru-cut Biopsies | Cytology Preparations | Bone Marrow | Toes | Post Mortem Samples

Packaging Samples

Samples should be submitted in 10% formalin in screw topped containers, sealed with tape to prevent leakage. The containers should be marked with at least the owner’s name. These should be wrapped in enough absorbent material to soak up the volume of liquid and placed in a sealable plastic bag before putting into a padded envelope or cardboard box.

Please try to ensure that cytology slides, whether or not submitted together with formalin-fixed specimens , are packaged in an airtight fashion to prevent formalin exposure to cytology slides. This significantly reduces the diagnostic usefulness of FNABs.

* It is a legal requirement that all specimens must be securely packaged. For further information click here to go to the Royal Mail website or here (pdf) for the IATA statutory regulations (IATA 650). To view the IATA statutory regulations on the goverments website go here.


All potential cases should be reported to the VLA. The VLA is currently willing to undertake mycobacterial culture free of charge in cases where the history, clinical signs and/or histopathological findings are suggestive of mycobacterial infection. Please contact Mr. Jahans prior to sending samples to ensure appropriate samples are submitted, and enclose case details when submitting samples. Please read one of our newsletter for further details: link

Submission Details

All samples must include a submission form with relevant details including a synopsis of the clinical history. Most importantly, where appropriate, a list of your clinical differential diagnoses for that case should be included. Where appropriate, please mark the animal outline with the site from which the tissue was removed. These details must be included, even if the case has been discussed on the telephone, as we discuss many cases each day and the information may be used (with consent) in the future for research purposes.

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We prefer not to send formalin through the post. Formaldehyde is cheaply and easily available through all of the wholesalers. Concentrated Formaldehyde (usually 40-50%) requires diluting 1 part of Formaldehyde with 9 parts water. Buffering is preferable, expecially in cases where bloody tissue is involved (i.e. spleen). It reduces the amount of formalin that is being sent through the postal system. If you wish to make up buffered formalin the following amounts of chemicals should be mixed together:

Buffered (ph 7.0) 10% formal saline:

Formalin (40% formaldehyde soln) 100 mls.
Distilled water 900 mls.
NaH2P04.2H20 (Sodium dihydrogen phosphate dihydrate) - 4.5 g
Na2HP04 (Sodium phosphate, (anhydrous)) - 6.5g

Where possible please send the whole lesion, and if more than 1cm in thickness make a deep cut into the substance to aid penetration of the formalin. Sample should be sent in a sealed container (not glass) with a WIDE neck and sample should be submitted with 10 times the volume of formalin to tissue. When handling large pieces of tissue it may be necessary to keep back parts of the organ(s) and submit small representative pieces. If these are not representative, submission of more tissue maybe indicated (postal regulation compliance).

If there are problems with this please contact us.

Skin Biopsies

Do not prepare skin biopsy sites in the normal way. They should not be rubbed, scrubbed or shaved. It is extremely rare for there to be any infectious complication from a biopsy site that has not been sterilised. As a general rule the larger the sample or the larger the number of samples submitted from one case the more information will be obtained.

For punch biopsies we find 6mm punch biopsies far superior to 3mm or 4mm. It is always best to take a number of biopsies from any skin case, including a biopsy from clinically normal skin. Lesions should be biopsied at a number of stages of development and if they are very discrete the junction between normal and abnormal tissue should be included. The charge for processing is the same no matter how many samples are submitted from an individual case. The biopsy should if possible follow the line of the hair shaft.

Auto-immune Skin Disease

For a suspected auto-immune skin disease a fresh lesion should be submitted wherever possible. To biopsy a vesicle or bulla a wedge biopsy should be used. Biopsy punches under these circumstances tend to rupture the vesicle. If older ulcerated lesions only are available the junction of the ulcer with normal tissue should be sampled.

Please note that steroid treatment obviously reduces the inflammatory process in skin disease. There is no set time for removal of steroids before carrying out surgical biopsy. We recommend, if possible, a withdrawal of steroids for at least 10 days but 2-3 weeks may be more preferable. However if steroids are given and the lesions are still continuing to develop, immediate biopsy without a withdrawal period will usually be acceptable.


Narrow strips of gut (and of other narrow samples such as skin, bladder and other tubular organs) should be adhered to slightly absorbent card to facilitate orientation and prevent curl. The fresh biopsy should be laid onto the card so that serum seeps into the card, left for 30 seconds and then placed into formalin. The absorbed serum then acts as a form of weak glue. This allows orientation, prevents curl and it also allows marking of the card to identify individual sites (wooden tongue depressors can also be used). Be as gentle as possible and handle the sample as little as possible. Do not use pins. Endoscopic biopsies of gut should be placed in formalin without handling.

Brain (and spinal cord)

Brain (including cerebellum and brain stem) should be fixed as soon after death as possible and should be removed from the skull. Small slits can be made into the lateral ventricles to aid penetration of formalin and the brain should be placed into a large volume of formalin and left, if possible, for 4 to 5 days to harden. It can then be submitted wrapped in formalin soaked cotton wool (rather than liquid formalin), in a plastic bag within a non-crushable container (NOT GLASS). The spinal cord is often difficult to extract. Care should be taken to dissect the cord from the vertebral column and should be loosely coiled and fixed in formalin in large container to prevent artefact.


Formalin does not penetrate eyes very well, but the recommended eye preservatives which are rapidly penetrating are also toxic and with COSHH regulation very serious consideration should be given as to whether the advantages of these fixatives are necessary. They are necessary if delicate retinal changes, including retinal separation, are to be examined. For all other intraocular conditions formalin is adequate. This includes tumours and inflammatory lesions in the eye, which are the most common lesions. DO NOT INCISE INTO THE EYE as this disrupts the tissue and makes it very difficult to cut in and orientate.

Tru-cut Biopsies

Tru-cut biopsies are very useful for investigating conditions of liver and kidney and also for external neoplasia, particularly where a full general anaesthetic is not appropriate. Always take more than one tru-cut biopsy sample and put them into formalin with the container filled to the top. This prevents significant shaking during the transportation in the post, and helps to prevent break-up of these tru-cuts, particularly if the tissue is friable.

Cytology Preparations

For body fluids, if possible please send the fluid sample and an air dried smear made at the time of sampling. Fine needle aspirate slides should also be air dried. Please do not stain slides. Ideally fluids should be submitted plain with a separate sample containing a few drops of formalin. These must be clearly labelled. All smears should be prepared and dried very quickly (do not use external heat sources) indeed to maintain cell morphology.

Please try to ensure that cytology slides, whether or not submitted together with formalin-fixed specimens , are packaged in an airtight fashion to prevent formalin exposure to cytology slides. This significantly reduces the diagnostic usefulness of FNABs.

Fluids are often submitted in EDTA (blood tubes) (i.e. tracheal/bronchial washes, pleural or abdominal fluid) which is usually indicated when transport times are short. Cells can undergo autolysis in transit in EDTA. Submission of an extra plain sample with one to a few drops of formalin solution (labelled formalin) is usually indicated. H&E stains are then performed on this sample and may help to preserve cell morphology.

Bone Marrow

Always if possible make smears of bone marrow and if possible include a small piece of fixed marrow to assess cellularity. These should be submitted with a concurrent air dried blood smear and any blood analysis result obtained previously. For those with little experience in bone marrow sampling techniques the descriptions that are given in the literature make this technique appear very easy. Probably less than 50% of bone marrow samples that we receive are suitable for full interpretation. If you have little or no experience in this type of sampling please ring us before embarking upon this.


Toes always present a problem. Swollen toes with areas of erythema do not look swollen once they are removed from the body where there is no other comparison, and erythema becomes a uniform grey with the formalin. With all toe lesions please indicate specifically the site, either in the written description or with a marker pen or Indian ink. If there are underlying radiological bone changes the radiograph would also be very useful. (This will be returned.)

Post Mortem Samples

In addition to obvious specific lesion samples, samples of all of the major organs should be taken. We may not process all of the tissues but they would be there should we wish to examine them. It should be remembered that some cases may have more than one condition occurring at the same time.