114. Kidney

Question 1

blood supply to kidney

Answer 1

renal arteries (dorsal) from Aomultiple arteries reported (more often in left kidney)interlobar–>arcuate (at corticomedullary jxn)–>interlobular–>afferent glomerularsmall capillaries seen in the capsule arising from phrenicoabdominal and adrenal arteries; anastomose with primary renal arteries “arterial circle”vasa recti from cortex and into medulla for resorption VEINS: left renal receives blood with left ovarian and testicularmutliple veins 13% dog 10% cats

Question 2

what is the functional unit of a kidney

Answer 2

nephron–>renal corpuscle (glomerulus and Bowman’s capsule) and renal tubules (ending at the collecting duct)glomerulus contains podocytes which sit on basement membrane and interdigitate to create pores btwn cells for filtration

Question 3

where is the macula densa located

Answer 3

btwn glomerulus capillary network and afferent arterymaintain auto regulation of renal blood flow

Question 4

filtration at the level of the glomerulus

Answer 4

< 60 kDa freely pass (water and small particles)>60kDa (albumin 69 kDa) have limited ability to passinherent negative charge of basement membrane also repels other negatively charged molecules (like albumin)glomerular filtrate is equivalent to plasma—300 mOs/L

Question 5

normal anticipated urine production

Answer 5

1-2 ml/kg/hr

Question 6

estimated renal blood flow

Answer 6

kidneys receive ~25% of animal’s cardiac output (HIGH BLOOD FLOW–greater than any capillary bed in the body)cortical flow is highestrenal blood flow = renal perfusion pressure/renal vascular resistancetone of afferent and efferent arterioles affect GFRincr tone of afferent, decr GFRdecr tone of efferent, incr GFR

Question 7

what is the concentrating ability based on

Answer 7

based on renal medullary hyperosmolarity (which is maintained by vasa recti counter current mechanism)hi medullary interstitium 1200-1400 mOs/L (50% made up from urea)if blood flow thru vasa recti is high (vasodilation, increased arterial P, increase fluid volume), concentrating ability is decreased or “medullary wash out”

Question 8

3 mechanisms to maintain medullary hypertonicity

Answer 8

1. urea diffusion into interstitium2. limited ability for water diffusion3. active transport of electrolytes to interstitium in thick proximal loop of Henle **

Question 9

diagnostic tests for the renal dz patient

Answer 9

1. PE 2. MDB3. BP4. BMBT (impaired with uremia)5. crossmatch/coagulation panel6. Ab rads (also T rads if neoplasia, trauma suspected)7. ab US +/- aspirate or biopsy8. IV excretory urogram/pyelogram9. CT with contrast angiography10. MR angiography11. scintigraphy to determine GFR (total or individual)

Question 10

risk of hemorrhage during or after surgery is increase in what patients?

Answer 10

azotemichypertensivethrombocytopenic

Question 11

normal kidney size on radiographs

Answer 11

N canine kidney 2-2.5 times length of adjacent vertebraN feline kidney 2-3 times length of adjacent vertebra

Question 12

type of intravascular contrast studies

Answer 12

—excretory urogram or IV pyelogram (can also inject into renal pelvis)does NOT provide quantitative informationposible that a kidney with very little function will opacify therefor do NOT confuse opacification with renal functionrads taken immediately, 5, 20, 40 minutes after injection contrast dose 400 mg I/kg

Question 13

toxicity of renal IV contrast studies

Answer 13

ARF—hypotension, anaphylaxis, allergic reactionsiodinated nonionic preferrediohexol (omnipaque)–240 mg/ml I

Question 14

phases of an excretory urogram

Answer 14

1. renal angiographic: immediate, arterial supply2. renal phase or blush: parenchymal3. excretory: collecting ducts to bladder

Question 15

true renal a genesis vs dysgenesis

Answer 15

a genesis lack kidney and ureterdygenesis lack kidney but ureter may be present RIGHT kidney is more frequently reported check for other urogenital abN

Question 16

renal calculi

Answer 16

mostly calcium salts (siamese and bichon frises calcium oxalate)do NOT dissolve with medical protocolstx options for stone removal:– lithotripsy– nephrotomy– pyelolithotomy– nephrectomy is end stage infected or nonfunctional

Question 17

T/F In cats with mild to moderate renal disease, the presence of renal calculi was NOT associated with progression of renal disease or in a difference in mortality rates from renal dz

Answer 17

TRUEpresence of stone did not put them at a higher risk of dz progression and/or mortalityresection of perirenal pseudocysts also did not prevent progression of any underlying renal disease

Question 18

types of renal neoplasia

Answer 18

majority of primary renal tumors MALIGNANTcats–LSAdogs–renal cell carcinomaother tumors: TCC, nephroblastoma, renal cystadenocarcinoma (nodular dermatofibrosis and uterine leiomyomas—-GSD), HSAab mets 50% (liver and LN) in dogstx unilateral nephrectomy

Question 19

contraindications to renal biopsy

Answer 19

–known end stage–owner unwilling to pursue further therapy–coagulopathy/severe hypertension–abscess–cysts–extensive polynephritis–ureteral obstruction–severe hydronephrosis

Question 20

appropriate renal biopsy

Answer 20

need 5-6 glomeruli, spring loaded biopsy instrument–percutaneous blind biopsy–US guided biopsy**–keyhole biopsy (flank open)–open laparotomy wedge/incisional occlusion renal artery for 20 min–laparoscopic biopsymajor implications < 10% (severe hemorrhage)

Question 21

two methods for nephrotomy

Answer 21

1. bisectional nephrotomy: sharp dissection2. intersegmental nephrotomy: slower, technically demanding, allows individual ligation of encountered vessels but less hemorrhage**no difference in GFR with either technique

Question 22

GFR after nephrotomy incision

Answer 22

closure of nephrotomy decr GFR 40-50% 21 days post opno clinical azotemia seensuture less closure minimally disturbed GFR

Question 23

indications for partial nephrectomy

Answer 23

“nephron sparing”very small tumors or traumamay be more appropriate option for animals with decrease GFRuncommonly performed—most often nephrectomy/nephroureterectomy

Question 24

if an owner refuses to spay their pet, what complication can occur after left nephrectomy

Answer 24

damage to left gonadal veinif remaining intact, need to ligate renal vein upstream (towards the kidney) to avoid damage to gonadal/ovarian vein

Question 25

what is renal descensus

Answer 25

mobilization of the kidney caudal (as with renal transplant—into iliac fossa)

Question 26

what is psoas hitch

Answer 26

cranial movement of bladder

Question 27

how much of normal renal function can return after 4 weeks of total obstruction

Answer 27

25%

Question 28

giant kidney worm

Answer 28

dioctophyma renale