15. urinary surgery 1

diagnostic testing for renal patients

• CBC / chem

• urinalysis, urine culture

• blood pressure

• thoracic radiographs

  • evaluate cardiac disease and/or metastasis

• buccal mucosal bleeding time

  • uremia may impair platelet adhesion/aggregation

• coagulation panel (PT/PTT/fibrinogen)

  • abnormalities rare with renal disease

• thromboelastography (TEG)

  • screens for hypercoagulability

kidney diagnostic imaging — survey radiographs

• evaluate size / shape of kidneys

• right lateral is best

• evaluate for urolithiasis (if calcium oxalate or struvite)

• dog: 2-2.5x vertebral length (cat 2-3x)

excretory urography / intravenous pyelogram

• iodine is filtered by urinary system

• qualitative test

• iodinated contrast is renal toxic

• pyelography — direct injection in renal pelvis

assess ureter size and look for obstruction

other kidney imaging (U/S, CT, MRI)

• U/S

  • good for architectural changes

  • dilated renal pelvices

  • U/S guided biopsy

• CT (with contrast)

  • ID cysts, tumors, etc.

  • CT angiography superior to EU for evaluating vasculature

• MRI

  • evaluate renal vessels, structural changes, etc.

pre-operative considerations for renal patients

• correct uremia, blood pressure, anemia, coagulopathies, electrolytes, etc.

• oncotic support

• monitor urine output

• avoid nephrotoxic drugs

  • aminoglycosides, NSAIDs

• avoid drugs that cause hypotension

  • acepromazine, reduce inhalants

• dopamine/dobutamine may be required

• epidurals, opiates can reduce anesthetic requirements

**renal disease impairs wound healing

kidneys — congenital defects

• agenesis or dysgenesis

  • agenesis: ureter absent

  • dysgenesis: ureter present

  • evaluate before nephrectomy

• renal ectopica

  • originate near aortic bifurcation and “ascend”

  • position doesn’t affect function

• fusion

  • “horseshoe” shaped; normal function

polycystic kidney disease

• rare in dogs; common in persian cats

  • congenital defect

• originate from renal tubular cells

• compress surrounding parenchyma and lead to renal failure

• treatment unsuccessful

  • consider renal transplant (only for cats; ↑ rate of rejection in dogs)

types of renal neoplasia

• primary tumors are rare

• majority malignant

• lymphoma most common in cats

• renal cell carcinoma most common in dogs

renal neoplasia treatment

• nephrectomy — consider partial nephrectomy if contralateral kidney is diseased

• chemotherapy — lymphoma (often systemic)

acquired renal cyst

• epithelial lined (true cyst)

• secondary to chronic nephropathy or incidental

• hypertension commonly associated

• U/S guided draining / ethanol infusion described

perirenal pseudocyst

• more common in cats

• fluid between capsule & parenchyma

  • not epithelial lined

  • mechanism unknown

• linked with chronic renal disease

when should renal biopsy be performed?

ONLY if results will change course of action — risky procedure

indications for partial nephrectomy

• animals with renal insufficiency or previous nephrectomy

• isolated lesion or trauma

indications for nephrectomy

• trauma

• persistent infection

• renomegaly

• obstructive calculi with persistent hydronephrosis

• neoplasia

• kidney donation

• make sure contralateral side is normal

  • only need ~30% nephrons to function normally

indications for feline renal transplant

• end-stage renal failure

  • decompensation despite appropriate medical therapy

  • start discussing when cat is in IRIS CKD stage 3

    • do not wait until patient is very ill & no longer a good surgical candidate

• irreversible acute kidney injury

findings that preclude renal transplantation

• neoplasia

• severe cardiac disease

• FeLV or FIV

• recurrent/existing UTI

• uncontrolled hyperthyroidism

• fractious temperament

• (stones = gray area; new kidney likely to end up with stones eventually)

feline renal transplant — pre-operative screening

• CBC / chem

• blood type (& cross-match to donor)

• thyroid hormone (T4)

• urinalysis / culture / prot:creat

• abd rads and U/S

• cardiac workup

• infectious disease screening

  • FeLV / FIV / toxoplasmosis

feline renal transplant — complications

• hemorrhage

• graft thrombosis

• ureteral obstruction (often scar tissue; can be stones)

• delayed graft function

• acute / chronic rejection

• hemolytic uremic syndrome

• urolithiasis

• retroperitoneal fibrosis

• immunosuppression complications

  • infection, diabetes mellitus, neoplasia (lymphoma)