What is a key point regarding renal healing?
the kidney is highly vascular and receives ~ 25% of the cardiac output
What should be evaluated pre-operatively for a kidney-related procedure?
*appropriate hydration status and electrolytes
*coagulation
-PT and aPTT
-fresh frozen plasma transfusion if prolonged
*RBCs
-anemia is treated with packed RBC transfusion if PCV < 25%
-erythrocytosis treated with therapeutic phlebotomy if PCV > 70% to avoid blood sludging and thrombosis
What are the characteristics of renal biopsy?
-ideal for acute progressive renal failure and protein-losing nephropathy
-avoid in cases of suspected neoplasia due to severe hemorrhage risks
-minimal effect on renal function in a normal animal
What are the contraindications to a renal biopsy?
-pyelonephritis/abscess
-severe hydronephritis
-uncontrolled coagulopathy
-severe systemic hypertension
-NSAIDs given within 5 days
What is the goal of a renal biopsy?
obtain a cortical sample
-medullary samples lead to more hemorrhage and kidney damage
What are the possible approaches to a renal biopsy?
-percutaneous ultrasound-guided
-laparotomy
-laparoscopy
How is a renal biopsy sample obtained?
-tru-cut needle in 16 or 18 gauge
-aim for cranial/caudal pole or outer 1/3 of long axis
-apply digital pressure for hemostasis after taking sample
What are the characteristics of renal biopsy complications?
-overall rate between 1 and 22%
-major complication rate around 9%; primarily due to hemorrhage
-less than 3% mortality rate
-more likely to have complications with thrombocytopenia, prolonged coagulation, creatinine greater than 5 mg/dL, and/or weight less than 5 kg
In which conditions is nephrectomy considered a salvage procedure?
-irreparable trauma
-severe uncontrolled pyelonephritis
-severe hydronephrosis with no renal parenchyma on imaging
-idiopathic renal hematuria/persistent life-threatening hemorrhage
What is the ideal treatment for idiopathic renal hematuria, and why?
renal sclerotherapy
-condition occurs bilaterally in around 20% of cases; cannot remove second kidney if the first was treated with nephrectomy
What are the characteristics of perirenal pseudocysts?
-not “true” cysts; no epithelial lining
-fluid accumulation around kidney with fibrous tissue lining
-compression from fluid leads to parenchymal damage and progressive disease
What are the treatment options for perirenal pseudocysts?
*palliative:
-intermittent percutaneous drainage
*surgical:
-removal of cysts
-open drainage
-omentalization
-avoid nephrectomy; poor outcomes if performed
What are the characteristics of ureteral healing?
-can seal damaged areas in 2 to 3 days
-can form strictures
-can heal without intervention if more than 50% of the circumference is intact
-urine leakage delays healing
-transection of ureters causes loss of peristalsis
-adhesions can temporarily or permanently inhibit peristalsis
What are the characteristics of ureteral obstruction?
-can lead to hydroureter or hydronephrosis
-some obstructions can cause mild dilation; renal pelvis < 5mm
-renal pelvis > 7mm is likely obstructed
-renal pelvis > 13mm should be considered obstructed
-renal blood flow decreases to 40% of normal within 24 hours and 20% of normal within 2 weeks
-want to identify and intervene ASAP
How does the relief time frame of a ureteral obstruction relate to GFR return?
-relieved within 4 days: 100% return of GFR
-within 7 days: 65% return
-greater than 7 days: 46% return
-greater than 14 days: 0% return
What are the possible causes of ureteral obstruction?
-ureterolith (most common)
-neoplasia
-stricture
-inflammatory tissue
-iatrogenic from ovariohysterectomy
What are the medical management steps in the case of ureteral obstruction?
-ureteral relaxants
-diuresis
-correction of hyperkalemia and azotemia
*often a poor prognosis if only medical management is done
What are the characteristics of a ureterotomy?
-requires advanced training and surgical magnification
-want to use 6-0 or 7-0 monofilament suture
-complications include immediate need for another surgery, stricture, progressive renal dysfunction, and urolithiasis recurrence
-mortality rate between 9 and 21%
What are the characteristics of ureteral reimplantation?
-requires advanced training and equipment
-available when the distal 33-50% is affected
-urine transit is decreased for 4 to 11 days; coordinated peristalsis improves after 3 to 4 weeks
-complications include uroabdomen and persistent obstruction
What are the steps to ureteral reimplantation?
-free ureter of attachments
-resect diseased portion
-form tunnel through bladder between body and apex
-pull ureter through bladder
-perform mucosa to mucosa anastomosis
What are the characteristics of ectopic ureters?
-lead to urinary incontinence
-ureteral opening is more caudal than normal bladder opening
-can have an intramural or extramural tunnel
What are the characteristics of intramural ectopic ureters?
-accounts for 90% of cases
-diagnosed via excretory urography and CT
-cystoscopy is diagnostic and allows intervention
-cystoscopic laser ablation is treatment of choice
-continence rate increases to 50-60%; can have issues with USMI
What are the characteristics of extramural ectopic ureters?
-rare in dogs
-ureter takes separate course from urinary tract and enters urethra or vagina
-requires surgical intervention; typically ureteral reimplantation
-nephrectomy done in cases of severe infection
-continence rates after surgery range from 22-59%
What are the characteristics of uroabdomen?
-diagnosed via abdominocentesis
-want to do fluid analysis and cytology to rule out sepsis
-want to treat hypovolemia quickly; then correct dehydration over 2 to 4 hours
-acidemia occurs when pH is less than 7.2 on blood gas
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