Complete urinalysis

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A complete urinalysis includes assessment of both the physical and chemical properties of urine. It requires minimal specialized equipment and be routinely performed by trained individuals in general veterinary practice. With proper sample handling and appropriate testing, urinalysis can provide vital information about the urinary tract and can also be an indicator of disease states in the liver, peripheral blood or endocrine system.

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6.10 Application of urine to the urine dipstick pad. (a) Placement of individual drops of urine on to each test pad, breaking the surface tension of each drop after placement. (b) Careful removal of excess urine to avoid oversaturation of the test pads and intermingling of reagents between test pads.
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6.11 Interpretation of urine dipstick test reactions is based upon the colour change that develops within the specific amount of time designated by the manufacturer. Distilled water was placed on the top dipstick for comparison with the lower two dipsticks, to which urine from two different patients was applied. The middle dipstick exhibits a strongly positive reaction for glucose and haem and moderate reaction for protein. The bottom dipstick reveals a weakly positive reaction for haem and protein.
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6.14 Unstained and new methylene blue stained urine sediment wet mounts. If desired, both the unstained and stained wet mounts can be prepared on a single microscope slide.
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6.15 Humidified Petri dish to preserve wet mounts. If there is to be a significant delay between the time that the sediment wet mount is prepared and the time that it is examined, it can be preserved in a humidified Petri dish created by moistening absorbent material at the bottom of the dish. Details on its construction are provided in Figure 6.8 (Step 10).
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6.16 New methylene blue stained urine sediment wet mounts. (a) Two crystals are present: a calcium oxalate dihydrate crystal (left) and a contaminating crystal from the new methylene blue (right). When crystals are observed in a stained wet mount, they should be verified in the unstained preparation. Note the numerous pale orange erythrocytes in the background, which are swollen by water uptake within the relatively hypotonic, dilute urine. (New methylene blue stain; original magnification X500) (b) Numerous budding yeasts are observed as contaminants in a new methylene blue-stained wet mount. When microorganisms are observed in a stained wet mount, they should be verified in the unstained preparation. (New methylene blue stain; original magnification X400)
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6.21 Positive haem reaction indicating the presence of intact erythrocytes. The positive haem reaction in this case indicates the presence of intact erythrocytes by its speckled green appearance. Compare this colour change to the diffusely green 3+ positive haem reaction of the middle dipstick in Figure 6.11 , which could either be due to intact erythrocytes, free haemoglobin or free myoglobin.
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6.24 Sulphosalicylic acid precipitation of a serially diluted protein solution. Sulphosalicylic acid protein precipitation has been performed on solutions containing a known amount of protein, demonstrating the semiquantitative results obtained by sulphosalicylic acid protein precipitation. A white precipitate is formed in protein-containing solutions. The amount of precipitate formed is directly proportional to the protein concentration. Here, the amount of protein present in each tube is decreasing from 4+ in the leftmost tube to negative in the rightmost tube.
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6.28 (a) Magnesium ammonium phosphate (struvite) crystals in feline urine sediment. A casket cover form is present (lower left). (Unstained; original magnification X500.) (b) Calcium oxalate dihydrate crystals in canine urine sediment. (c) Calcium oxalate monohydrate in feline urine sediment. Two morphologies are present: most crystals resemble picket fence boards and a single dumbbell-shaped crystal is found near the centre of the field. The picket fence board morphology is highly suggestive of recent ethylene glycol ingestion. This form appears similar to magnesium ammonium phosphate crystals, but calcium oxalate monohydrate crystals are always flat, while magnesium ammonium phosphate crystals form three-dimensional prisms (a). (Unstained, original magnification X400) (d) Calcium carbonate crystals forming spheres with radial striations in equine urine sediment. These crystals have not been reported in dogs or cats. Sulphonamide crystals may form globules with radial striations and could be mistaken for calcium carbonate crystals. (e) Bilirubin crystals in canine urine sediment. Copious sheaves of needle-like, dark orange bilirubin crystals are found clumped within urine sediment from a dog with hepatobiliary disease. (f) Amorphous phosphate crystals in urine sediment from alkaline urine from a clinically normal dog. Compare with the amorphous urate crystals in Figure 6.40a . (g) Uric acid crystals in canine urine sediment. Several flat, six-sided, diamond-to-rectangular shaped uric acid crystals are present in acidic urine from a clinically normal Dalmatian. (h) Ammonium biurate crystals. Dark golden-brown spheroids and sarcoptic mange-like ammonium biurate crystals are identified in urine sediment from a patient with hepatoencephalopathy caused by portovascular malformation. (i) Cystine crystals in canine urine sediment. Cystine crystals, which are never a normal sediment finding, form flat hexagons with unequal sides in acidic urine. They most commonly occur in male dogs of certain breeds with proximal renal tubular disease and are a risk factor for cystine urolithiasis. Note the large number of sperm in the background. (j) Sulphonamide crystals in canine urine sediment after administration of sulpha-containing antibiotic. A sheaf of pale yellow needle-like sulphonamide crystals is seen surrounded by a few yellow globular forms. (b, d–j unstained; original magnification X100)
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6.29 Translucent hyaline renal tubular cast (arrowed) in canine urine sediment. Note the evenly separated, parallel sides and rounded end of the cast, which allows this cast to be distinguished from a mucus thread (see Figure 6.32c ). A transitional epithelial cell is touching the cast. A few smaller leucocytes are also seen in the background. (Unstained; original magnification X400)
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6.30 (a) Cellular renal tubular cast comprised desquamated renal tubular epithelial cells in the urine sediment of a dog with acute kidney injury. The cells within the cast are well preserved, suggesting that the cast had recently formed and was dislodged from the renal tubule before appreciable cellular degeneration occurred. (New methylene blue stain; original magnification X400) (b) Granular renal tubular cast in feline urine sediment. Although the cast is curvilinear, note the evenly separated parallel sides. Falling between intact cellular casts and aged waxy casts, granular casts represent an intermediate stage of cellular degeneration. A low number of granular casts are occasionally seen in urine from clinically normal animals. (c) Cholesterol-rich waxy renal tubular cast in feline urine sediment, indicating that a chronic renal tubular lesion is present. These casts have characteristic sharply broken, blunt ends and are less translucent than hyaline casts. (b–c unstained; original magnification X400)
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6.31 (a) Fatty renal tubular cast in feline urine sediment, consisting of granular cellular remnants admixed with non-staining spherical lipid droplets. Feline renal tubular epithelial cells are relatively lipid rich; therefore, these casts are more commonly seen in cats. (New methylene blue stain; original magnification X100) (b) Haemoglobin renal tubular cast (arrowed) in canine urine sediment. The haemoglobin content of the cast imparts a dark reddish-brown colour. When observed in patients with haemolytic disease, this finding specifically indicates intravascular haemolysis, rather than extravascular haemolysis. (c) Bright orange bilirubin-containing mixed granular and waxy renal tubular cast in canine urine sediment. The cellular material is more degenerated in the right portion of the cast. (b–c unstained; original magnification X400)
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6.32 (a) Curved hyaline renal tubular cast within an active canine urine sediment. The cast is surrounded by several pale orange erythrocytes and some leucocytes and transitional epithelial cells. There are also several bacteria and sperm in the background. Note the size of the cast relative to the surrounding cells and the difference in magnification of this image compared with (b). (Unstained; original magnification X400) (b) Large, synthetic fibre within an active canine urine sediment. The fibre, which could be mistaken for a cast, is surrounded by numerous cells that are much smaller than the fibre. Note the uneven irregular separation of the parallel sides, the repetitive internal structure and the dull blunt end of the fibre. (Unstained; original magnification X100) (c) Mucus thread in feline urine sediment. Mucus threads could be mistaken for hyaline casts, but are distinguished by their irregularly spaced twisting parallel sides and pointed wispy ends. (New methylene blue stain; original magnification X100)
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6.34 (a) Squamous epithelial cells in canine urine sediment. Note their angular borders, abundant translucent cytoplasm and single condensed nucleus. (Unstained; original magnification X400) (b) Mixed population of epithelial cells and leucocytes in canine urine sediment. Four transitional epithelial cells are visible (arrowed). Note their pleomorphism and relatively large nuclei. An angular squamous epithelial cell is present (arrowhead). Some leucocytes with segmented nuclei and fewer small round cells are scattered throughout the field. (SediStain™; original magnification X400)
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6.35 (a) Size comparison of cells in an active canine urine sediment. Erythrocytes are the smallest cells (black arrow), leucocytes are larger than erythrocytes (white arrow) and transitional epithelial cells are larger than leucocytes (arrowhead). Squamous epithelial cells are the largest cells (not pictured). (Unstained; original magnification X400) (b) Caudate transitional epithelial cells (top) exfoliated from the renal pelvis of a cat with pyelonephritis. Beneath the epithelial cells, two smaller neutrophils are found. (New methylene blue stain; original magnification X400)
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6.36 (a) Rounded renal tubular epithelial cell and bacteria in canine urine sediment. A small round cell is present (lower right) that can be presumptively identified as a renal tubular epithelial cell on the basis of the eccentric placement of its round nucleus. There are several bacilli in the background. (Unstained; original magnification x500) (b) A large number of cuboid to low columnar renal tubular epithelial cells in feline urine sediment. Most cells are cuboidal or low columnar with eccentric nuclei. Fewer cells are rounded. Though not identified within a cast, this large number of renal tubular epithelial cells is abnormal and suggests an active tubular lesion. (New methylene blue stain; original magnification x400)
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6.37 (a) A large number of neoplastic epithelial cells in canine urine sediment. It is apparent that the nuclear:cytoplasmic ratio is markedly increased, although a stained preparation would improve visualization of nuclear details. The arrow is pointing to a cohesive cell cluster. (Unstained; original magnification x400) (b) Neoplastic epithelial cells in a dry-mounted canine urine sediment prepared for routine cytology as described in Figure 6.33 . There is a cohesive sheet of neoplastic transitional epithelial cells. Note the absence of inflammation and the presence of morphological changes consistent with malignancy (i.e. variation in cell and nuclear sizes, very high nuclear:cytoplasmic ratio, open chromatin pattern and prominent, large nucleoli). Compare the morphology of these cells with the non-neoplastic transitional epithelial cell in Figure 6.41b . Several erythrocytes are also present in the background. (Diff Quikstain; original magnification x500)
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6.38 Seven lipid droplets from feline urine sediment, floating in different focal planes. Note their variable size, refractile, jewel-like appearance and greenish hue, all of which are features that distinguish them from erythrocytes (not pictured). (Unstained; original magnification x400)
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6.39 Variable erythrocyte morphology in canine urine sediment. Ten pale orange crenated erythrocytes (black arrows) are present along with three colourless erythrocyte ghosts (white arrow). Compare with Figures 6.16a and 6.35a . A single diamond-shaped calcium oxalate dihydrate crystal (arrowhead) is in the middle of the field. (Unstained; original magnification x500)
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6.40 (a) Pyuria, bacteriuria and amorphous urate crystalluria in urine sediment from a Dalmatian. A leucocyte that has a segmented nucleus is present (black arrow). Note that it is stippled grey and transmits less light than an erythrocyte (not pictured). There are several bacilli in the background (arrowhead) and two aggregates of brownish-black amorphous urate crystals (white arrows). Compare these with the amorphous phosphate crystals in Figure 6.28f . (Unstained; original magnification x500) (b) Pyuria and bacteriuria in canine urine sediment. Several leucocytes and bacilli are surrounding a bacterial microcolony (upper left corner) in urine sediment from a dog with bacterial cystitis. (Unstained; original magnification x400)
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6.41 Bacteriuria in urine sediment from a Miniature Schnauzer with glucosuria. The dog was isosthenuric (specific gravity 1.008) and mildly glucosuric (5.6 mmol/l). (a) A mixed population of bacteria (bacilli and cocci) is present near a transitional epithelial cell (arrowed). Note the absence of pyuria. (New methylene blue stain; original magnification x500) (b) Bacteriuria in dry-mounted urine sediment from the same dog. This slide was prepared using the method described in Figure 6.33 . Several cocci, small bacilli and large bacilli are present with a single transitional epithelial cell (arrowed). This method of slide preparation improves visualization of bacterial morphology and increases the sensitivity and specificity for the detection of bacteriuria. (Wright–Giemsa stain; original magnification x500)
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6.45 (a) Fungal hyphae, bacteriuria and pyuria in canine urine sediment. Septate branching fungal hyphae are present, surrounded by leucocytes and numerous bacteria. (SediStain™; original magnification x400) (b) Budding pseudohyphae of in canine urine sediment. (c) ovum in canine urine sediment. A single amber ovum is present surrounded by a few lipid droplets. Note the placement of the bipolar caps, which are slightly askew, and the granular texture of the outer shell, distinguishing this ovum from that of . (b–c unstained; original magnification x400)
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6.46 (a) Pyuria and sperm in the urine of a Persian cat with bilateral renomegaly. An aggregate of leucocytes (left) and a single sperm (right) are present. Sperm are a potential contaminant of voided samples. (Unstained; original magnification x1000) (b) Glass chip contaminants in canine urine sediment. Glass chips are common contaminants of urine sediments that may be mistaken for crystalluria. (Unstained; original magnification x500)
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