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 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 650 statutory regulations. To view the IATA statutory regulations on the government website click here (new window).
Fixed tissues for histopathology from cases where Mycobacteria is listed as a differential will be reported as normal, and additional special stains performed, if indicated.
If unfixed tissues are submitted for culture and sensitivity, which does not routinely include culture for Mycobacteria, those will be retained in the event referral for Mycobacterial culture is indicated. This may be free of charge in cases where the history, clinical signs and/or histopathological findings are suggestive of Mycobacterial infection.
For further information see:
All samples must include a submission form with relevant details including a synopsis of the clinical history. Computer printout’s usually contain too much irrelevant information, so please summarise the important information for samples submitted. A list of your clinical differential diagnoses for that case will be helpful . 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.
We prefer not to send formalin through the post. Formaldehyde is cheaply and easily available via NVS.
Where possible please send the whole lesion, and if more than 1cm in thickness make a deep cut into the tissue to aid penetration of the formalin. Samples should be sent in a sealed container (not glass) with a WIDE neck. Very large samples can be fixed for a few days in the practice and then submitted in damp cotton wool instead of in liquid formalin with appropriate package in an uncrushable container/box. It may be easier to submit small representative pieces of a large lesion by post while retaining the whole lesion at the practice until a diagnosis has been reached.
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 give better results than 3mm or 4mm biopsies. It is always best to take a number of biopsies from any skin case. 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 biopsy should if possible follow the line of the hair shaft. Any crusts/surface exudates should be carefully preserved.
Auto-immune Skin Disease
For a suspected auto-immune skin disease a recent lesion should be submitted wherever possible. Vesicles are fragile and often rupture clinically resulting in crusting. Such crusts should be carefully preserved. To biopsy an intact vesicle or bulla a wedge biopsy should be used as small biopsy punches tend to rupture vesicles. If only older ulcerated lesions are available the junction of the ulcer with normal tissue should be sampled.
Please note that steroid treatment 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 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 card or filter paper 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.. This allows orientation, prevents curl and it also allows marking of the card to identify individual sites. Be as gentle as possible and handle the sample as little as possible. Do not use pins. Endoscopic biopsies of gut should be immediately placed in formalin without handling.
Brain (and spinal cord)
Brain (including cerebellum and brain stem) should be fixed as soon after death as possible following removal 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 will provide sufficient detail for most intraocular conditions including common inflammatory lesions and neoplasia. If you are expecting subtle retinal injury then please contact us to discuss alternative fixatives.. DO NOT INCISE INTO THE EYE as this disrupts the tissue and making it difficult to prepare and orientate.
Tru-cut biopsies can be useful for investigating conditions of liver and kidney and 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.
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. All smears should be prepared and dried quickly (do not use external heat sources) to maintain cell morphology.
Please 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. Exposure 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 ideal when transport times are short. However cells can undergo autolysis in transit in EDTA. Submission of an extra plain sample with a few drops of formalin is also helpful if transport time is likely to be extendedthis sample should be labelled as containing 10% formalin.
Always 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 prior to sampling.
Swollen toes with areas of erythema often do not look swollen once they are removed from the body and fixed with formalin. With all toe lesions please indicate the site, either in the written description or with a marker pen or Indian ink. If there are underlying radiological bone changes we normally require the associated radiograph for diagnosis (this will be returned if a digital image is not available.)
Post Mortem Samples
In addition to any obvious specific lesions, samples of all of the major organs should be taken. Please indicate clearly where you believe the lesions are and we will process these tissues first. Remaining tissue will be processed if it required by a pathologist. It should be remembered that some cases may have more than one condition occurring at the same time.