Sample taking and basic clinical pathology

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In birds, clinical examination and history taking are rarely sufficient to result in a complete diagnosis. Many diseases present with similar clinical signs, so it is therefore necessary in most investigations to take clinical samples for laboratory analysis. There are many options available to clinicians and this chapter describes some of the more commonly performed tests. : Blood sampling – jugular vein; Blood sampling – brachial vein; Blood sampling – caudal tibial vein; Crop wash.

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12.1 Typical sample: two x 1.3 ml heparinized blood samples and two air-dried smears. This is sufficient to allow electrolyte analysis plus a full profile and electrophoresis. (© John Chitty)
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12.2 A good quality air-dried blood smear greatly assists the haematologist. (© John Chitty)
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12.7 Right jugular vein in a Cockatiel. A modified ringer’s grip allows access to the jugular vein in this Greenfinch. (© John Chitty)
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12.8 Ulnar (basilic) vein in a Senegal Parrot. (© John Chitty)
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12.9 Caudal tibial vein. King Vulture. The same region in a King Vulture before vigorous cleaning. (Note the urates on the skin: this is a feature of New World vultures and the skin must be cleaned before venepuncture.) Conure. The vein is short and tortuous, and hard to utilize. (Note: green staining on the feet is from perch pigment.) (© John Chitty)
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12.10 Arterial blood sampling in parrots. The arrows indicate the brachial artery. (Courtesy of A Montesinos)
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12.11 Avian blood smear stained with Diff-Quik (original magnification X400). Heterophil (left) and monocyte (right) in a blood smear (original magnification X1000). Avian lymphocyte (original magnification X1000). Avian eosinophil (original magnification X1000). Avian basophil (original magnification X1000). Clump of thrombocytes with normal morphology (original magnification X1000). (a, d, © John Chitty; b, c, e, f, © Nick Carmichael)
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12.12 Haematocrit tube. This test allows packed cell volume measurement, analysis of total solids from the plasma, and assessment of the buffy layer (between red cells and plasma) which gives a rough estimation of white cells. (© John Chitty)
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12.15 Cloacal swabbing is more likely to give meaningful cytology and culture results than use of voided samples. (© John Chitty)
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12.16 Normal parrot faecal Gram stain. Note the mixture of mainly Gram-positive cocci and rods. (© John Chitty)
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12.17 Abnormal parrot faecal Gram stains (original magnification X100). Budding yeast cell indicates active yeast growth. This is a significant finding even if found in small numbers, as is development of pseudohyphae. Overgrowth of Gram-negative rods is usually a sign of gut imbalance and is normally only seen in parrots with enteritis (it is normal in raptors). Avian gastric yeast (, previously known as ‘Megabacterium’). A few may be found in normal birds. However, large numbers in thin birds are likely very significant. Gram-positive sporulating rods are likely to be spp. and are not a normal finding. This parrot had acute enteritis. (© John Chitty)
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12.18 Faecal smear. It is important that the smears are not too thick. (© John Chitty)
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12.19 A drop of clear fluid is extruded from the tip of a feather. The initial blood-tinged portion is discarded and the second drop used to make a smear. (© John Chitty)
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12.20 Collection of feather pulp from a blood feather. (© John Chitty)
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12.21 Fresh skin biopsy specimen placed on paper. Paper and biopsy sample in formal saline pot for submission. (© John Chitty)
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12.22 Aspirates taken from feather pulp showing large numbers of mixed inflammatory cells (heterophils and monocytes) in a case of pulpitis. (© John Chitty)
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12.23 Trichomonads from a Budgerigar crop wash. These parasites may also be found in faecal samples. (© John Chitty)
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12.24 When sampling the upper respiratory tract, use of the cranial portion of the choana is less likely to result in contamination than use of the nostril. However, screening of healthy birds via choanal swabbing is unlikely to achieve meaningful results. (© John Chitty)
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12.25 Plain preparation of a joint aspirate showing urate crystals (gout) (original magnification X400). The stained preparation. Staining will wash out crystals, though ‘negative staining’ may remain (original magnification X1000). Therefore joint aspirates should always be air-dried and examined as plain preparations before staining. (© John Chitty)
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12.27 Large numbers of coccal bacteria and inflammatory cells indicate septic peritonitis and coccal infection. (© John Chitty)
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12.28 Joint aspirate in septic arthritis. Note the highly proteinaceous background and inflammatory cells. (© John Chitty)
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