Chapter 114 Kidneys Flashcards
What % of dogs have multiple renal arteries?
And cats?
Which side more common?
13% dogs
10% cats
Left more common (makes sense, aorta on L)
How many interlobar arteries are there?
3-7
From what vessels do renal capsular arteries arise?
Most commonly phrenicoabdominal and adrenal arteries
(also ovarian)
How many nephrons does a canine kidney have?
500,000
Where in the kidney are the renal corpuscles located?
Cortex
What is the name of the cells surrounding the glomerular capsule (bowmans capsule)
Podocytes
What is the size of filtration slits between glomerular capsule podocytes?
What other feature enhances the selective nature of the capsule?
60,000 daltons
Negative charge so repels other negatively charged particles (like albumin)
What is normal urine production in dogs and cats
20 - 45 ml/kg/day
Where does L gonadal vein insert?
L renal vein
What % caridac output do the kidneys receive?
What is that in ml/min/g (of kidney tissue)
25%
4 ml/min/g (highest in cortex)
How is renal blood flow calculated?
Renal perfusion pressure / renal vascular resistance
What if GFR rate relative to renal plasma flow
20%
Briefly describe the flow of water, electrolytes and urea through the nephron
- Bowmans capsule: Ultrafiltrate of blood
- PCT: 67% of Na+ and H20 actively moved out of PCT, also Cl-, K+ and HCO3-
- Thin limbs of Henle’s loop: Maintenance of medullary hypertonicity by countercurrent exchange i.e urea)
- Thick (ascending) limb of Henle’s loop: 25% Na+, Cl-, K+ actively out (this is where frusemide works (inhibitd Na2Cl-K+ symporter).
- DCT: 4% Na actively out, PTH –> Ca2+ reabsorbtion
- Collecting duct: Final regulation of water, urea, and acid secretion (ADH –> insertion of water permeabl channels here)
What causes medullary washout?
Increased medullary blood flow (through long term ivft)
What is the osmolarity of renal medullary interstitial fluid and how does this compare to interstitial fluid elsewhere?
3 mechanisms that maintain this renal medullary osmolarity
Renal medullary osmolarity 1200-1400 mOs/L vs 300 mOs/L elsewhere
Maintained by:
- Facilitative diffusion of large molecules (urea) into interstitium
- Limited ability of water to diffuse into interstitium
- Active transport of Na, K, Cl into interstitium from thick portion of loop of Henle (most important)
What % contribution does urea make to osmolarity of renal medulla?
40-50%
What parts of nephron are impermeable to urea?
Thick loop of Henel (i.e. last part of loop, DCT, cortical collecting duct
(i.e. last 3 parts of nephron except medullary part of collecting duct, which allows urea to moce out to maintain the medullary interstitial osmolarity)
What was effect of transparenchymal mattress suture in parenchyma?
Caused necrosis, fibrosis, scarring and atrophy
What factors are associated with inceased risk of bleeding during surgery?
Azotaemia (uraemia impairs platelet adhesion + aggregation)
Hypertension
Thrombocytopaenia
What % of dogs undergoing renal biopsy had abnormal coag panel?
Cats?
40% dogs
52% cats
How is normal renal size assessed on rads in dogs?
And cats?
Dogs 2 - 2.5 x lenth of adjacent vertebra
Cats 2 - 3 x “
By what mechanism is contrast filtered by kidneys?
Passive glomerular filtration i..e not a marker of renal function
When are rads taken for ivu
Which lateral is preferred
5, 20, 40 mins + more as necessary
R lat (increases distance between kidneys)
What is contrast iodine dose
400 mg iodine/kg
What are the phases of renal contrast excretion?
- Renal angiographic phase
- Renal phase
- Excretory phase
What ws accuracy of CT for diagnosing multiple renal vessels?
92%
How is individual renal function assessed pre-nephrectomy?
Dynamic renal scintigraphy
What two radiopharmaceuticals can be used for dynamic renal scintigraphy?
What is the difference?
-
99mTc-DTPA [diethylenetriaminepentaacetic acid).
- Removed by glomerular filtration - no excretion or reabsorbtion and does not bind to plasma protein
-
99mTc-MAG3 [mercaptoacetyltriglycine])
- 90% secreted by renal tubules, 10% removed by glomerular filtration.
- Better in patients with very limited renal function and for performing renal perfusion studies ro evaluate renal transplant patients
How is 99mTc- DTPA affected by furosemide?
Doesnt change GFR but does decrease half life (i.e. so can perform surgery earlier)
What is the condition called if kidney abesnt but ureter present?
Renal dygenesis
What is renal dysplasia?
Disorganized development of renal parenchyma
Where are ectopi ureters usually situated?
Pelvic area (they usually ascend from aortic bifurcation)
What breed are predisposed to PCKD
What is incidence in that preed
Mode of inheritance?
And dog breed?
Persians
37-38%
Autosomal dominant
Bull terriers
What dog breed ad cat breed is overepresented for calcium oxalate urolithiasis
Bichon and Siamese
List 4 options for renal calculus removal
- Extracorporeal shockwave therapy
- Endoscopic nephrolithotomy
- Nephrotomy
- Pyelolithotomy
What is most comon feline renal tumour/
And canine
Cats lymphoma
Dogs renal carcinoma (85% of cases)
What is the condition affeting GSD skin + kidneys?
What is metastatic rate?
What is gene?
Renal cystadenocarcinoma + nodular dermatofibrosis (+ uterine leiomyoma)
50% mets
FLCN gene
List 6 paraneoplastic syndromes seen with renal tumours
- HO
- Polycythemia
- Hypercalcaemia
- Hypoglycaemia
- Leucocytosis
- Peripheral neuropathy
IN dogs with primary renal tumour, what are 2 most common sies of mets?
Ipsilateral adrenal and liver
In dogs with renal tumour, what was MST with:
carcinoma
Sarcoma
Nephroblastoma
What factor was associated with better outcome?
Carcinoma 16 months
Sarcoma 9 months
Nephroblastoma 6 months
Nephrectomy = better survival (not chemo!)
Comment on imaging
Right renal and ureteral calculi with ureteral obstruction and right renal hydronephrosis.
Smoothly marginated, oval, white calcific opacities in the area of the right kidney and ureter are visible on lateral (A) and ventrodorsal (B) radiographs.
C, Excretory urography.
Ventrodorsal view 5 minutes after intravenous injection of contrast medium. Peripheral opacification of the right kidney is identified without accompanying central or pyelographic opacification.
HOw do aquired renal cysts differ from perirenal pseudocyts?
Aquired renal cysts = epithelial lined
Perirenal pseudocyst = lacks epithelial lining - usually fluid accumulation between renal parenchyma and capsule
What clinical exam finding was present in all dogs with aquired renal cyst?
Systemic hypertension
How are aquired renal cysts managed?
Alcohol ablation:
- Cysts were drained percutaneously in anesthetized dogs using a spinal needle inserted under ultrasound guidance.
- The cyst was then infused through the same spinal needle with 95% ethanol, using a volume equivalent to half of that removed.
- After 3 minutes the alcohol was slowly removed, and alcoholization was repeated with a 1 : 10 lidocaine-alcohol solution, which was also removed after 3 minutes.
One dog developed bleeding during ethanol infusion; the procedure was interrupted, and no further treatment was required.
How are renal pseudocysts treated
Excision (dont remove kidney - those cats did worse)
Can also do repeated percutaneous drainage
What type of fluid is in perirenal pseudocyst?
What conditon are they linked with
Transudate or modified transudate
CKD
What method has been used experimentally to manage renal trauma
Synthetis mesh wrapping (had better creatinine clearance ratio than partial nephrectomy)
How can idiopathic renal haematuria be diagnosed? And managed?
Dx Cystoscopy
Local sclerotherapy = Renal pelvic infusion of povodine-iodine + silver nitrate (resolution in 4/6 improvement 2/6)
Other options = renal arterial embolization or ureteroscopic electrocauterization
N.B Up to 1/3rd develop bilateral disease
What parasite affect kidney?
Giant kidney worm.
Tx nephrectomy
What part of kidney should biopsy be obtained from?
What size and type of needle?
3 approaches
Renal cortex
14G spring loaded biopsy needle
Biopsy approaches:
- PErcutaneous
- US guided percutaneous
- Lap
- Keyhole
IF trying to close renal biopsy site and not possible due to suture oullthrough, what is liekly problem?
Arterial supply not appropriately occluded
List 5 factors associated with higer rate of complication after renal biopsy
What is amjor complication rate and main complication
- Thrombocytopaenia
- Prolonged clotting times
- Creat > 440 umol/L
- PAtient age >4 yrs
- Weight <5kg
9% major complication. Haemorrhage most common
List complications of renal biopsy
- hematuria,
- hydronephrosis secondary to renal pelvis or ureteral obstruction by blood clots,
- renal infarction,
- damage to renal vasculature,
- intrarenal arteriovenous fistula formation,
- infection,
- cyst or intrarenal hematoma formation,
- renal fibrosis
Name 2 nephrotomy techniques. Which is preferred?
Bisectional (preferred = scalpel cut) vs intersegmental (dissection with eg freer or scalpel handle)
What was complication rate with pigtail nephrostomy tube placement?
10%
1 uroabdomen, 1 accidental dislodgement
