 |
|
Get a PDF version of Newsletter here If
you need Acrobat Reader click the image THIS
MONTH
Fine
Needle Aspirates of Internal Organs - are they any use?
Before taking FNA's of internal organs, it is important to consider the nature of the disease. It is important to remember when sampling an organ that unless there is diffuse involvement an FNA may not sample an affected area. Focal lesions are best sampled with ultrasound guidance. The structure of the organ should also be considered. For example, liver function is dependant on a lobular structure. An FNA will not help assess tissue architecture and will give no information about possible fibrosis. For assessing architecture a wedge biopsy or Tru-cut biopsy are needed. FNAs are however very useful for assessing diffuse cellular infiltrates such as lymphoma and diffuse cellular changes e.g. hepatic lipidosis. Deep FNA of any organ should not be attempted if there is any bleeding disorder or haemangiosarcoma is suspected. A coagulation screen should be performed including a platelet count, prothrombin time (OSPT) and activated partial thromboplastin time (APTT). von Willebrands factor concentration should be measured in breeds at risk. Lung: Transthoracic FNAs are most useful when there is diffuse parenchymal disease or a discrete mass or masses. A specific diagnosis may not be possible but an FNA can be useful to differentiate between inflammation and neoplasia. After aspiration the patients respiratory and cardiac function should be checked frequently for the first few hours. A thoracic radiograph should be examined 1 hour after aspiration or at any time if there is increased respiratory distress to look for evidence of pneumothorax. Liver:
Hepatic cytology is useful for the initial evaluation of hepatomegaly.
Ultrasound guided FNAs are useful for focal lesions. FNAs are not helpful
where hepatic architecture is important such as in chronic active hepatitis,
nodular hyperplasia or fibrosis. The patient should be carefully monitored
for 24hrs after liver FNA.
Prostate: This is the most common deep FNA. It is useful for investigation of enlargement of the prostate whether due to hyperplasia or neoplasia. Squamous metaplasia can also be identified. If there is asymmetrical enlargement, the FNA should be directed to the enlarged area. Aspirated material should be expressed onto clean microscope slides and spread either with another slide as a blood smear or by gently placing another slide on top and gently drawing the slides apart, both slides being submitted. Smears should be air dried before packing in slide mailers. Do not use coverslips. Jane
Miller BVetMed MRCVS FRCPath
Test Name: Cytology: Cellular morphology Top Don’t Judge a Book by its Cover - Urolith Analysis “Integrated analysis of uroliths brings together a range of analytical techniques to provide as accurate an analysis of the stone as possible.” Does anyone remember the good old days of transitional metal chemistry and growing a `crystal garden,’ or am I just showing my age? Crystals formed around a nidus, often a hair, suspended in a solution maintained in a state of super-saturation. Our chemistry group used to run competitions to see who could grow the largest and most even specimens. When considering urolith
formation in dogs and cats, the principles are exactly the same. There
must be a nidus around which precipitation begins, and then, if the urine
is a supersaturated solution, growth continues, slowly but surely, layer
by layer. If the solute changes, for example due to dietary manipulation
or alteration in the pH, a pre-existing crystal may function as a new `nidus
‘and a urolith of mixed composition is the result.
Size, shape, colour and location of the uroliths should be established; in addition, the species and breed may be relevant. The composition of the outer layers and the nidus should be analysed separately. The nature of the nidus may be crystalline, organic, artefact, drug or drug-metabolite based, but often produces vital information as regards the pathogenesis of the disease, and is likely to influence management of the case whether attempting to dissolve stones or prevent their recurrence post surgery. METHODS
OF ANALYSIS
Prior to analysis the calculus is ground to a fine powder, which is then tested with various chemical reagents. Limited information is provided as regards the composition of the calculus but obviously no information is gained about the structure. This highlights a major disadvantage in that nothing is learned about the nature of the nidus. Other problems include the inability to identify matrix or certain organic materials that may be present. Chemical analysis is widely
used by laboratories employing complex integrated analysis techniques,
but as a stand alone method is certainly of limited use.
Integrated analysis
X-ray diffraction is of limited use in identifying amorphous material and constituents present in very small quantities. Infra-red spectroscopy is particularly useful when it comes to the identification of non-crystalline materials. Amorphous or fatty calculus constituents will be revealed and drug or drug metabolites and artefacts which may be present can be readily identified. Fluorescence is exhibited
by many organic compounds when excited by light of specific wavelength,
and this can be invaluable when attempting to detect or measure compounds
present in extremely low concentrations.
Until now the real and possibly only drawback of this integrated approach has been the limited availability of diagnostic laboratories able to perform these highly sophisticated techniques, making the process unacceptably time consuming and potentially expensive. We are now in a position to offer our clients this `state of the art’ service at a reasonable cost and with a realistic turn around time of between 7 and 10 days. The test code is UCA. A dry calculus should be submitted. Chemical analysis will still be available if specifically requested by the practice, however, comprehensive integrated analysis will surely be the method of choice when dealing with most cases of canine and feline uroliths. Susan F Beck BVMS MRCVS Next issue: Part 2 The Composition of Uroliths Top
Next Meeting: Thurs 14th November 2002 Venue: Swallow Hotel, Samlesbury, Preston New Road, Preston. (Leave M6 J31, follow A59 signs to Blackburn, hotel just before 1st traffic lights) Speaker: Dr A Coughlan BVSc Cert VA DSAS (Orth) PhD FRCVS Working up the lame dog "Tricks and Traps" Case book studies: If you would like to present an interesting case please contact Jane Miller on 01253 899215 or e-mail To book your place, request further information or a location map call Joanne Kenyon on 01253 899215 or e-mail Top
Quote “An excellent way to top up your CPD" Interpreting
Proteinuria
A trace or 1+ reaction is usually considered normal with a specific gravity of 1.035 or greater although the guidelines have to be approximate, as the test is so sensitive. As a rough guide, 2+ or more of protein in urine with specific gravity of 1.035 or more. In a urine with a specific gravity less than 1.035 any amount of protein is significant and warrants a further investigation. Urine sediment examination is the first consideration when there is proteinuria. Inflammation or infection of the lower tract, or haematuria will affect protein levels. If there is no haemorrhage or inflammation then proceed to check a urine protein:creatinine ratio (UPCR). The UPCR has superseded the 24-hour urine measurement test for purely practical reasons but has shown to be well correlated as a measure of protein excretion. Normal UPCR in dogs and cats is less than 0.4. Ratios higher than 1.0 are abnormal. The range is higher in dogs treated with prednisolone. Occasionally there will appear to be a discrepancy between the dipstick and UPCR tests. The UPCR is more accurate. Significantly raised UPCR can indicate glomerulonephritis and amyloidosis. Renal biopsy will be required to distinguish between the two. Bence Jones proteins are free light chains, which are produced in myelomas. These do not cause a positive dipstick reaction but are positive on precipitation testing. Protein electrophoresis is indicated in these patients and most of the urinary protein will be found in a monoclonal spike in the beta or gamma regions. Dr Geraldine Hale BVM&S PhD CertPM MRCVS
Test Name: Urine Protein Creatinine Ratio Test Name: Urine Protein Electrophoresis Top Rabies Blood Test Reminder During last summer we were
frequently presented with demands for urgent rabies blood test results
because “the client was going on holidays in a few days”. It is important
to remember that there needs to be a 6 month gap between the blood test
and the animals RETURN to the UK.
A phobia is an irrational,
uncontrollable fear of a specific object or situation.
Zoophobia, the fear of animals, is one of the most common. These are just some of the specific zoophobias:- ailurophobia: cats
|
|
Test Protocols || Disease Investigation Protocols || Sampling Guides || Newsletters || Interesting Links NationWide
Laboratories
Lancefield House, 23 Mains Lane, Poulton-le-Fylde, Lancashire, FY6 7LJ, England Telephone +44 (0) 1253 899215 Fax +44 (0) 1253 891934 |
