Upper urinary tract disorders

What are the three main functions of the kidneys?

-Excretion of waste

-secretion of hormones

-regulation of fluid, electrolytes, and acid-base balance

What substances do the kidneys excrete from the blood?

Water-soluble toxins produced by cellular metabolism

What hormones are produced by the kidneys?

Erythropoietin (EPO), vitamin D, and renin

What defines chronic kidney disease (CKD)?

Structural and/or functional kidney abnormalities lasting longer than 3 months; irreversible

What glomerular compensatory mechanisms occur early in CKD?

hyperfiltration, hypertension, and hyperperfusion of remaining nephrons

How much nephron loss leads to dilute urine in CKD?

Approximately two-thirds of nephrons lost

What clinical abnormalities occur when 75% of nephrons are lost?

Proteinuria, hypertension, azotemia, and uremic death

What are common causes of CKD?

Calculi, congenital disease, hypertension, immune-mediated disease, AKI, infection, ischemia, or unknown causes

What does urine concentrating ability indicate about kidney function?

Adequate concentrating ability indicates functional kidneys

What is considered a normal urine specific gravity (USG) in dogs and cats?

• Dogs >1.030

• Cats >1.035

How does USG help localize azotemia?

Differentiates prerenal, renal (primary), and postrenal causes

What characterizes prerenal azotemia?

-Azotemia with concentrated urine due to decreased renal perfusion that leads to ischemic damage

-response to fluid therapy: decreased BUN/CREA

What conditions cause prerenal azotemia?

Dehydration, hypovolemia, hypotension

What characterizes postrenal azotemia?

Obstruction or rupture of the urinary tract distal to the kidneys

What defines primary (renal) azotemia?

Azotemia + inappropriate USG due to acute or chronic kidney disease

What USG values suggest primary renal disease?

• Dogs <1.030

• Cats <1.035

What clinical signs are commonly seen in CKD?

Weight loss, anorexia, V/D, lethargy, weakness, PU/PD

What physical exam findings are common in CKD patients?

Muscle wasting, heart murmurs, dehydration, assessment of renal size and shape, oral exam, rectal exam, acute blindness

What oral abnormalities are associated with uremia?

Uremic breath, oral ulcers, ptyalism

What diagnostics are recommended for CKD evaluation?

UA with UPC ratio, blood pressure, CBC, biochemistry panel, imaging, kidney function test

Why is Symmetric Dimethylarginine (SDMA) useful in kidney disease?

It detects decreased glomerular filtration rate (GFR) earlier than creatinine

What are the primary goals of CKD treatment?

Treat underlying disease, manage complications, prevent progression

What complications of CKD must be managed?

Hyperphosphatemia, acidemia, potassium imbalances, anemia, hypertension, proteinuria

Why is hydration critical in CKD patients?

Dehydration further decreases GFR and worsens azotemia

Why is dietary therapy the cornerstone of CKD management?

It prevents disease progression from stage 2-3 and reduces uremic crises

What dietary restrictions are recommended for CKD patients?

Restricted protein, phosphorus, and sodium with high-quality protein

What additional dietary components benefit CKD patients?

Omega-3 fatty acids and buffering capacity (alkaline diet)

Why should diet transitions be gradual in CKD patients?

To avoid food aversion and protein-calorie malnutrition

What indicators suggest protein-calorie malnutrition?

declining BCS, poor coat quality, hypoalbuminemia

Why are feeding tubes sometimes recommended in CKD?

To ensure long-term feeding for adequate calories, fluids, and medication administration

How often should CKD patients be monitored?

Monthly initially, then every 3-6 months minimum

What is uremic syndrome?

Accumulation of uremic toxins affecting function of every organ system

What is a uremic crisis?

Severe uremia requiring aggressive fluid therapy

What defines acute kidney injury (AKI)?

Acute rapid onset of renal parenchymal injury that is potentially reversible

How does AKI differ from CKD?

AKI is acute and potentially reversible; CKD is chronic and irreversible

What are common causes of AKI?

Hemodynamic failure, nephrotoxins, infection, and obstruction

What are the phases of AKI?

Initiation, extension, maintenance, and recovery

What urine specific gravity is often seen in AKI?

Fixed USG between 1.008-1.018

What physical exam findings suggest AKI?

Good body condition, dehydration, normal or enlarged kidneys, possible pain

What is hemodynamic failure in AKI?

Renal hypoperfusion due to severe hypotension, shock, or dehydration

Why is early hemodynamic AKI reversible?

No structural kidney damage has occurred

What nephrotoxins commonly cause AKI?

Ethylene glycol, NSAIDs, aminoglycosides, grapes/raisins, lilies

Why is leptospirosis important in AKI patients?

It is a common cause, zoonotic, and dogs shed organisms for months

What urinary obstruction can cause AKI?

Bilateral ureteral obstruction leading to severe azotemia

What type of stones commonly cause ureteral obstruction?

Calcium oxalate uroliths

What are key treatment goals for AKI?

Restore perfusion, remove toxins, treat infection, relieve obstruction, fluid therapy

How should fluids be managed in AKI?

Match fluid input to urine output and monitor closely

What is renal replacement therapy?

Dialysis or transplantation to replace kidney function

What is intermittent hemodialysis (IHD)?

Extracorporeal blood filtration to remove toxins and correct imbalances

What does AEIOU indicate for dialysis use?

-Acid-base problems

-Electrolyte issues

-Intoxication

-Overload of fluids

-Uremia

What interventional procedures are used for upper urinary tract disease?

Shockwave lithotripsy, ureteral stenting, SUB system, surgery

What is a subcutaneous ureteral bypass (SUB)?

A device that bypasses obstructed ureters to allow urine flow

Why is renal and ureteral surgery high risk?

Kidneys are sensitive to ischemia and ureteral healing is limited