Renal Failure Overview

Acute Renal Failure (ARF) vs Chronic Renal Failure (CRF)

• ARF results from acute glomerular or tubulo-interstitial injury; CRF is the final outcome of multiple chronic renal diseases.
• ARF presents with oliguria or anuria, while CRF is characterized by polyuria, often leading to irreversible damage.
• Both conditions involve azotemia, but ARF lacks clinical manifestations typical of renal disease, unlike CRF, which often shows uremia.

Types of Azotemia

• Prerenal Azotemia: Caused by renal hypoperfusion (e.g., heart failure, shock, hemorrhage).
• Renal Azotemia: Occurs due to direct damage to the renal tissue.
• Postrenal Azotemia: Results from urinary obstruction.

Clinical Pathology Findings

• Common symptoms include anemia (due to erythropoietin loss), azotemia (increased BUN and creatinine), and hypoproteinemia leading to edema.
• Metabolic acidosis arises from bicarbonate loss, contributing to hypocalcemia through phosphate retention and decreased renal activity.
• Hypocalcemia promotes parathyroid hyperplasia and subsequent bone resorption, which can lead to fibrous osteodystrophy and fractures.

Clinical Findings in Renal Conditions

• Symptoms include polyuria, neurologic issues (e.g., uremic encephalopathy), gastrointestinal ulcers (due to bacteria and ammonia), vomiting, hypertension, and pulmonary edema.

Gross Findings in Renal Failure

• Kidneys appear small, firm, with irregular surfaces, and have a thinned cortex; capsule adhesion complicates removal.
• Gastrointestinal tract shows signs of "uremic gastritis" with ulcerations and mineralization.
• Foul odor and ulcers may be observed in the oral cavity; soft tissue and lung mineralization can occur.
• Parathyroid glands show hyperplasia, and bone can exhibit fibrous osteodystrophy.

Congenital Renal Anomalies

• Agenesis: Bilateral agenesis is not compatible with life.
• Renal Hypoplasia: Contralateral hypertrophy compensates for unilateral hypoplasia.
• Renal Dysplasia: Abnormal renal tissue development.

Polycystic Kidney Disease

• Characterized by enlarged, pale kidneys containing 1-5 mm cysts, producing a "Swiss cheese" appearance upon dissection.

Horseshoe Kidney

• A condition where kidneys fuse at either cranial or caudal poles, functioning normally despite anatomical changes.

Renal Infarction

• Results from local ischemic necrosis due to renal artery obstruction, often indicating cardiovascular issues in cats.
• Infarcted tissue presents swelling, congestion, and a progression to necrotic and fibrotic scarring.

Analgesic Nephropathy

• Caused by NSAIDs inhibiting cyclooxygenase, reducing PGE2 production which is necessary for vasodilation in kidney arterioles; this leads to renal crest necrosis.

Hydronephrosis

• Dilation of the renal pelvis with progressive parenchymal atrophy due to urinary obstruction (e.g., stones, prostatic issues).
• Early intervention may restore function; prolonged obstruction risks irreversible damage and increases infection chances.

Amyloidosis

• Caused by amyloid deposition, leading to functional tissue interference and adjacent cell atrophy.
• Grossly presents as enlarged, firm, pale organs with a "waxy" appearance in kidneys.

Nephritis

• Characterized by inflammation of renal parenchyma.
• Classified according to infection route (ascending or descending) and histologic features (suppurative or non-suppurative).

Glomerulonephritis (GN)

• Identified histologically as membranous (capillary thickening) or proliferative (increased cellularity).
• Most cases are immune-mediated due to antibody-antigen binding or deposition of immune complexes in glomeruli.

This quiz covers the key differences between acute renal failure (ARF) and chronic renal failure (CRF). Learn about their symptoms, causes, and effects on the body, including conditions like oliguria, anuria, azotemia, and uremia. Dive deep into renal pathology and enhance your understanding of kidney-related diseases.