Urinary Tract Disorders

Question 1

history related to renal system issues

Answer 1

– Nonspecific (eg weight loss, depression, etc)
> May be mistaken as colic
– Volume of water intake, volume of urine produced
– Anuria, oligouria, polyuria vs pollakiuria
– Posture, dysuria or stranguria
– Appearance of urine

Question 2

what components of the urinary tract can we feel with trans-rectal palpation

Answer 2

– Bladder, region of ureters
– Caudal pole of left kidney

Question 3

what sampling methods do we use for urinalysis?

Answer 3

– Free catch midstream sample
– Catheterization of bladder
– (Cystocentesis in neonatal foals)

Question 4

urinalysis - gross appearance considarations

Answer 4

– Colour: straw coloured (may be quite dark yellow)
– Clarity: may be turbid (calcium carbonate crystals and
mucus)
– Odour

Question 5

should we use our whole urine sample for urinalysis? why?

Answer 5

• Split the sample (for later culture if indicated)

Question 6

how much renal loss for isosthenuria? what can give false elevations of SG?

Answer 6

– >75% of renal function loss before isosthenuria is
detected
– False elevations in presence of excessive proteinuria

Question 7

what test to confirm proteinuria? why is this needed?

Answer 7

• False positive trace protein in alkaline urine
• Sulfosalicylic acid (SSA) test to confirm
• Differentiate glomerular disease vs. urinary tract
  infection/hemorrhage/inflammation

Question 8

what dipstick values are unreliable in horse?

Answer 8

– Dipstick leukocytes and specific gravity are unreliable

Question 9

threshold for glucosuria?

Answer 9

– Glucosuria (renal threshold: 9-10mmol/L)

Question 10

“blood” in urine may be:
- how to tell?

Answer 10

• Erythrocytes
• Hemoglobin
• Myoglobin
  – Evaluate by sediment microscopy and/or protein
  electrophoresis

Question 11

Urinalysis
* Sediment Examination values:

Answer 11

– RBCs < 5/hpf
– WBCs < 5/hpf
– Bacteria: scant only
– Epithelial cells: occasional only
– Crystals > calcium carbonate, struvite, calcium oxalate
– Tubular casts (protein or cellular debris) > evaluate sample soon after collection and frequently

Question 12

cbc can reveal what urinary tract issues?

Answer 12

– Inflammatory leukogram may be seen with renal
infection (not lower regions of UT)

Question 13

serum biochem values that help us evaluate urinary system?

Answer 13

– Urea
– Creatinine
– Electrolytes and trace minerals

Question 14

Urine Fractional Excretions
- what are these for?

Answer 14

Evaluation of renal tubular function
– Simultaneous evaluation of urine electrolytes or trace
minerals and blood values:
* Na, K, Cl, Ca, Mg, Phos
* Need to consider dietary influences
<><><><>
FEa = ([urinea] x [serum creatinine]) x 100/
([seruma] x [urine creatinine])

Question 15

ultrasonography methods of evaluating the urinary tract, and what they are good for?

Answer 15

• Trans-rectal
  > Bladder, prostate, ureters
• Trans-abdominal:
  > Kidneys: Size, shape, Architecture, echogenicity, corticomedullary differentiation
  > Urachus (foals)

Question 16

how to do a renal biopsy? complications?

Answer 16

• Ultrasound guidance
• Possible complications:
  > Subcapsular hemorrhage
  > Hematuria
  > Intestinal perforation

Question 17

Water Deprivation Test
- purpose
- what is it? when to do it?

Answer 17

• Evaluates concentrating ability of the kidneys
• Serial evaluation of urine specific gravity in the
  presence of induced dehydration
  > Choose patients judiciously (not azotemic) and monitor closely during and after the test
  > Stop once s.g>1.025 or 5% body weight loss observed

Question 18

cystoscopy - how to perform? what can we see?

Answer 18

• Sedation
• Sterilization of endoscope
• Clean opening to urethra
• Lots of lube!
• Visualization of:
  – Urethra (tears, inflammation, strictures, accessory sex glands)
  – Bladder (stones, sabulous debris, neoplasia, ruptures)
  – Ureteral openings (assess urine production from each kidney, sample each)

Question 19

how can we assess bladder integrity?

Answer 19

• Catheterization of bladder to infuse dye, then
  abdominocentesis
  – eg. ruptured bladder in foals

Question 20

common disorders of the kidneys in horses

Answer 20

– Renal failure (acute / chronic)
– Diabetes insipidus
– Psychogenic Polydipsia
– Pyelonephritis

Question 21

common disorders of the ureters in horses

Answer 21

• ectopic ureters

Question 22

common disorders of the bladder in horses

Answer 22

– Bladder rupture
– Cystitis
– Neoplasia

Question 23

common disorders of the urethra in horses

Answer 23

– Obstruction, rupture
– Accessory sex glands

Question 24

acute vs chronic renal failure in horses
- what is the difference?

Answer 24

• Acute RF:
  – Loss of renal function occurring over hours to
  days
  – Toxic or hypoxic/ischemic causes
  <><><><>
• Chronic RF:
  – Loss of renal function occurring over weeks to months
  – Uncommon in horses

Question 25

Acute Renal Failure * Results in:

Answer 25

– Failure to excrete nitrogenous wastes – Failure to maintain homeostasis of body fluids and electrolytes

Question 26

Causes of ARF:

Answer 26

– Vasomotor (decreased renal perfusion) * Dehydration, hypotension <><><><> – Nephrotoxic compounds: * Aminoglycosides * NSAIDs * Vitamin D * Pigments: myoglobin, hemoglobin * Cantharidin (Blister beetle toxicosis) <><><><> – Interstitial glomerulonephritis

Question 27

ARF – Clinical Signs

Answer 27

ARF is usually secondary, and signs are more related to the primary disorder – Depression – Anorexia – Dehydration, tachycardia – Hyperemic mucous membranes – Oliguria or anuria – Colic?

Question 28

ARF – Diagnosis

Answer 28

Combine urinalysis with serum biochemistry – **Azotemia without urine concentration** – Blood electrolyte disorders: * Hyponatremia, hypochloremia * (Variable potassium) * Hypocalcemia, hyperphosphatemia * Metabolic acidosis – Urine GGT/Creatinine? +/- Hematuria, proteinuria, glucosuria, pyuria, casts <><><><> Trans-rectal palpation – Caudal pole of L kidney <><><><> Ultrasonography – Loss of corticomedullary differentiation <><><><> Monitor urine output – Anuria, oligouria, polyuria

Question 29

ARF – Treatment

Answer 29

* Improve renal perfusion: **Fluid therapy** – Correct both hypovolemia plus electrolyte disorders > Physiologic saline > Treat hyperkalemia (NaHCO3, Ca++ Borogluconate, dextrose) <><><><> * Discontinue nephrotoxic drugs or alter dosing interval (peak and trough drug concentrations) <><><><> If anuric/oliguric: – Diuresis > Furosemide > Mannitol – Renal Vasodilation > (Dopamine – low dose) <><><><> Monitor urine output and blood pressure – Body weight – Peripheral edema <><><><> * Wean off fluids slowly (several days) * Nutritional support * Treat underlying disease process * Peritoneal dialysis?

Question 30

ARF – Prognosis

Answer 30

Depends on: – Inciting cause – Duration of insult – Response to treatment > Anuria/oliguria → polyuria > Monitor serum creatinine