Canine Pyelonephritis Study Guide

Overview and Clinical Importance

Pyelonephritis is a bacterial infection of the renal pelvis and parenchyma, representing a significant upper urinary tract infection (UTI) in dogs. It is an important cause of acute kidney injury (AKI) and acute-on-chronic kidney disease. The condition is more common in middle-aged to older dogs, with females being overrepresented. Escherichia coli is the most commonly isolated pathogen, accounting for greater than 50% of cases.

Pyelonephritis typically results from ascending infection from the lower urinary tract, though hematogenous spread can occur rarely. The infection can be acute, causing sudden kidney injury, or chronic, leading to progressive renal damage and potential renal failure. Without early diagnosis and appropriate treatment, pyelonephritis can progress to sepsis, permanent kidney damage, and death.

Relevant Anatomy

The canine kidney is a bean-shaped, retroperitoneal organ located in the dorsal abdomen beneath the sublumbar muscles. The kidney consists of an outer cortex (containing glomeruli and convoluted tubules) and an inner medulla (containing loops of Henle and collecting ducts). The medulla projects into the renal pelvis as the renal crest.