Ch 114 - Kidneys Flashcards by Bro ECVS

How often are multiple renal arteries reportedly found?
In which kidney is this most common?

13% of dog kidneys
10% cat kidneys
Left kidney is more common

Right kidney more commonly has multiple renal veins

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Where do the capsular arteries commonly arise from?

Phrenicoabdominal and adrenal arteries

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What is the role of the vasa recta capillaries?

Extend from the cortex into the medulla, reabsorbing water from the collecting ducts and returning it back to systemic circulation
Help to maintain hypertonicity of the renal medulla through countercurrent exchange system

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What structure helps to maintain renal autoregulation of blood flow?

Macula densa (between glomerulus and afferent arterioles)

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What cells within the glomerulus are responsible for filtration?

Podocytes - water and small particles under 60,000 daltons can freely pass through the filtration slits
Inherent negative charge of the glomerulus basement also enhances the selective nature of filtration

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What is normal urine production?

20-45ml/kg/d

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What is the osmolality of the glomerular filtrate and of the medullary interstitial fluid?

Glomerular filtrate - 300mOs/L
Medullary interstitial fluid - 1200-1400mOs/L

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What is normal renal blood flow?

Approx 25% of CO
4ml/min/g of renal tissue

Calculated as renal perfusion/renal vascular resistance

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How does GFR relate to blood flow?

GFR is roughly 20% of renal plasma flow

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What determines the concentrating ability of the kidney?

Based on renal medullary hyperosmolarity which is maintained by the vasa recta through a counter-current mechanism

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What can cause decreased concentrating ability of the kidney?

Increased blood flow through the vasa recta
- Vasodilation
- Increased arterial pressure
- Increased fluid volume

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What mechanisms create medullary interstitial hyperosmolarity?

Faculative diffusion of large molecules (urea) into the interstitium
Limited ability of water to diffuse into interstitium
Active transport of Na, K, Cl and other electrolytes into the interstitium from the thick portion of the proximal loop of Henle

Urea contributes 40-50%. Absorbed in the collecting ducts UT-A1, stimulated by ADH. It is then recycles by moving to thin limb of Loop of Henle

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What suture pattern caused increased renal parenchymal damage?

Horizontal mattress
- parenchymal necrosis, fibrosis, scarring and atrophy

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List some indications for renal surgery

Unresponsive pyelonephritis
Perinephric abscess or cyst
Unilateral renal neoplasia
Severe renal trauma
Ureteral consitions causing severe irresolvable hydronephrosis

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What factors increase the risk of haemorrhage during renal surgery?

Hypertension
Thrombocytopaenia
Azotaemia - inhibits platelet adhesion and aggregation. Should perform BMBT

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What is the rate of pulmonary metastasis with primary renal neoplasia?

Dog: 16-48%
Cat: 43%

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Which lateral radiographs is better for viewing both kidneys?
What is the normal kidney size?

Right lateral
Dogs: 2-2.5x length of adjacent vertebra
Cats: 2-3x length of adjacent vertebra

What imaging modality of best for determining the GFR (and therefore function) of the kidneys?

Nuclear scintigraphy

Plasma clearance tests are more accurate but more difficult to perform and time consuming

What radiopharmaceuticals can be used for scintigraphy of the kidney?

Technitium 99m - DTPA (diethylenetriaminepentaacetic acid)
Technetium 99m - MAG3 (mercaptoacetyltriglycine) - better for patients with very limited renal function and for performing renal perfusion studies to evaluate transplant patients

Where is the most common location of renal ectopia?

Pelvis

What breeds are predisposed to polycystic kidney disease?

Persians (37-38% of breed)
Bull Terriers

What breeds are overrepresented with renal calculi?
What is the most common calculi?
List potential causes of renal calculi

Siamese cats, Bichon Frise
Calcium oxalate

Oversaturation of the urine with calculogenic substances
- Organ dysfunction
- neoplasia
- Increased Ca intake
- Drugs
- Increased intestinal absorption
- Impaired renal reabsorption
- Excessive skeletal mobilisation

List options for stone removal

Extracorporeal shockwave lithotripsy
Nephrotomy
Pyelolithotomy
Endoscopic nephrolithotomy (intracorporeal lithotripsy)

What are the most common renal neoplasias in cats and dogs?

Cats: Lymphome
Dogs: Carcinoma

What inherited neoplastic condition of the kidneys can effect young GSD?

Renal cystadenocarcinoma with nodular dermatofibrosis - Bilateral multifocal renal tumours - Firm nodules of dense collagen in the skin and SQ - Feline common also have uterine leiomyoma - Mutation of FLCN gene, affecting folliculin (a potentially tumour suppressing portein) - 50% mets

List paraneoplastic syndromes which can be seen with renal neoplasis

- Polycythaemia and thrombocytosis in cats - HyperCa - Hypoglycaemia - Leucocytosis - Peripheral neuropathy

What is the rate of bilateral renal neoplasia?

4-32%

What is the MST for renal neoplasia?

- Carcinoma - 16m - Sarcoma - 9m - Nephroblastoma - 6m - HSA - 278d (haemoperitoneum has significantly shorter survival 62d

List some DDx of abnormal appearance of the kidney

- Developmental abnormalities - Calculi - Neoplasia - Acquired renal cyst - Perirenal pseudocyst - Renal abscess - Trauma - Kidney worms (Dioctophyma renale)

List some treatment options for severe renal trauma?

- Ureteronephrectomy - Wrap in semielastic polyglactin mesh - Wrap in polyglycolic acid mesh - Sterile, nonabsorbable cyanoacrylate for small lacerations *When comparing mesh to partial nephrecomy, creatinine clearance ratio was 0.93 for mesh and 0.58 for partial nephrectomy*

List some contraindications for renal biopsy What needle can be used?

Contraindications: - Uncontrolled coagulopathy - Hypertension - Large or multiple renal cysts or abscesses - Extensive pyelonephritis - Ureteral obstruction - Severe hydronephrosis Monopty biopsy needle

What is the complication rate of surgical renal biopsy? What factors have been associated with increased complications?

- Complications 1-21.7% (Major in 8.9% - Mortality rate less then 3% Factors associated with complications: - Thrombocytopaenia - Prolonged clotting times - Creatinine above 5mg/dL - Patient older than 4yo - BW less than 5kg

List some indications for nephrotomy

- Biopsy - Removal of nephroliths or other obstructive lesions - Chronic infection - Persistent haematuria of renal origin - Persistent hydronephrosis

What are the 2 options for nephrotomy?

- Bisectional nephrotomy (sharp dissection of the renal parenchyma) - Intersegmental nephrotomy (Blunt dissection) Bisectional recommended - faster, easier, no difference in post-op GFR between the 2 techniques

What should be the maximum occlusion time of the renal vessels?

20min

How do you close a partial nephrectomy?

- Overlapping mattress sutures through the parenchyma and apposition of the overlying capsule - If cannot be apposed, can tack omentum to exposed surface

List potential complications following a partial nephrectomy

- Haemorrhage - Urine leakage - Urine fistula

What is the expected orientation of the renal vessels?

- When in normal orientation, renal vein is ventral to renal artery - When the kidney is rotated ventromedially, renal artery is lateral to renal vein

How many ports are required for a laparoscopic nephrectomy?

- 3 to 4 port technique (1 caudal to umbilicus, 1 caudal to last rib and 1 cranial to pelvic limb for triangulation)

List some DDx of abnormal appearance of the kidney

- Developmental abnormalities - Calculi - Neoplasia - Acquired renal cyst - Perirenal pseudocyst - Renal abscess - Trauma - Kidney worms (Dioctophyma renale)