Page 69 - Zoo Animal Learning and Training

Chapter 6: Minimum Database: Spinal Surgery 63

• genetic disease testing; • Proteinuria: suggests urinary tract hemorrhage or inflammation,
• specific assays for infectious agents or immune‐mediated dis- or renal disease due to glomerular or tubular dysfunction.
eases (serology, PCR). Transient proteinuria can be associated with strenuous exercise
or fever.
• Glucosuria: usually due to diabetes mellitus or stress‐associated
Urinalysis hyperglycemia (in cats), although can also be the result of acute
Although not routinely included in the MDB for most surgical can- renal failure or Fanconi syndrome.
didates, urinalysis is an essential component of the initial evalua- • Ketonuria: associated diabetic ketoacidosis, starvation, or fasting.
tion as an easy and inexpensive diagnostic and monitoring test. • Bilirubinuria: caused by hepatic disease, posthepatic bile duct
There are many parameters on the biochemistry profile that cannot obstruction, or hemolysis.
be interpreted without a urinalysis, especially when evaluating • Hematuria: suggests urinary tract infection (UTI), urolithiasis,
renal, hepatic and endocrine functions, as well as the acid-base sta- coagulopathies, trauma, or neoplasia.
tus. Urine is preferably collected by cystocentesis and is submitted
fresh along with the blood samples. The complete urinalysis Sediment Evaluation
includes the evaluation of the physical, chemical, and formed ele- To assess for the presence of erythrocytes, white blood cells,
ment characteristics of urine. More specifically, the routine urinaly- epithelial cells, casts, crystals, and microorganisms (bacteria,
sis consists of a visual inspection to determine color and clarity/ fungi, parasites).
turbidity, measurement of urine specific gravity, chemical evalua- • Pyuria: suggests UTI. Discospondylitis, prostatic disease, and
tion using a urine reagent strip (routine) or a chemical analyzer, and pyometra are frequently associated with UTI.
microscopic analysis of the sediment to assess mostly for the pres- • Hematuria: UTI, urolithiasis, coagulopathies, trauma, or
ence of cells and crystalluria [13]. Additional tests can be performed neoplasia.
on urine to evaluate changes in glomerular filtration (determina- • Microorganisms: support UTI or pyelonephritis in the presence
tion of microalbumin level and urine protein/creatinine ratio), of pyuria.
endocrine abnormalities (urine cortisol/creatinine ratio), presence • Crystalluria: ammonium biurate crystals are indicative of high
of Bence Jones proteinuria (associated with multiple myeloma), serum ammonia levels, frequently associated with portosystemic
urate crystals (seen with portosystemic shunts), urine organic acids shunting, but can also develop secondary to severe primary
levels, or fungal hyphae (associated with systemic aspergillosis). hepatic disease and naturally in Dalmatians.
• Casts: can suggest chronic renal disease or renal tubular
Visual Inspection necrosis.
Normal urine is clear with a light yellow to amber color. Possible
alterations include the following [13].
• Yellow–orange discoloration: presence of bilirubin, fluorescein, Hemostasis Assays
concentrated urine. Spinal surgery complications due to excessive bleeding are not
• Brown–black discoloration: bile pigments, myoglobin, uncommon. Surgical bleeding can be exacerbated by acquired or
methemoglobin. congenital hemostatic disorders as a result of a defect in one or
• Green–blue discoloration: presence of biliverdin, methylene more of the three major components of hemostasis: (i) vascular wall
blue. integrity, (ii) platelets (numbers or function), and (iii) coagulation
• Red: blood, myoglobin. cascade. The necessity for a presurgical hemostatic assessment is
• Milky: pyuria, lipiduria, phosphate crystalluria. indicated by patient‐associated and procedure‐associated factors
[18]. The potential risk of the presence of a hemostatic disorder in a
Urine Specific Gravity specific patient together with the expected risks of bleeding for the
Normal gravity should be greater than 1.030 in dogs and greater specific surgical procedure should be taken into account. Patient‐
than 1.035 in cats with normal renal function and normally hydrated associated risk factors are evaluated based on medical history, phys-
or dehydrated. Urine specific gravity is an essential value for deter- ical examination (for any evidence of bleeding), the underlying
mination of the underlying cause of azotemia and for differentiating disease, current and past medications, and previous abnormal
prerenal from renal azotemia. A decreased urine specific gravity results. Regarding procedure‐associated factors, hemostatic assess-
(isosthenuria, hyposthenuria) suggests an inability of the kidneys to ment is recommended in spinal surgeries where massive noncom-
concentrate urine. Hyposthenuria (gravity <1.007) can occur sec- pressible bleeding is possible, such as with extensive cervical dorsal
ondary to increased fluid intake, or renal or endocrine diseases approaches in large and giant breed dogs.
(hypoadrenocorticism, hyperadrenocorticism). Hyposthenuria is A minimum hemostatic screening has to include a platelet count,
usually associated with a lack of response to antidiuretic hormone coagulation times (prothrombin time, PT and activated partial
(ADH; nephrogenic diabetes insipidus), absence of ADH (central thromboplastin time, aPTT), and a buccal mucosal bleeding time.
diabetes insipidus), or excessive water consumption. While a platelet count identifies a quantitative deficit in platelets, a
bleeding time evaluates the qualitative function of the platelets. The
Chemical Evaluation mucosal bleeding time assesses platelet function in animals with
Chemical evaluation is routinely performed with a urine reagent normal platelet counts through the penetration of the buccal
strip (dipstick) specifically designed for this purpose or by using a mucosa with a sharp blade (usually a standardized disposable
chemical analyzer if sent to a laboratory. Urine reagent strips allow lancet) and assessment of the time required for clotting to occur.
the semi‐quantitative assessment of pH, proteinuria, glucosuria, Normal bleeding time should be less than 4 min in healthy dogs and
ketonuria, bilirubinuria, hematuria, and several other parameters. 3 min in cats [15].