This study aimed to evaluate the renal function of six bitches of various breeds and ages, with open pyometra, attended in the Small Animal Medical Clinic sector of the Veterinary Hospital from Federal University of Campina Grande, through the measurement of laboratory tests: urea and creatinine serum, dosage of the urinary Protein-Creatinine Ratio (PCR), urinary gamma-glutamyltransferase (GGT) and determination of the renal resistivity index (RI). The levels of urea and creatinine were elevated in 16.6% (1/6) of the female dogs; the urinary protein-creatinine ratio was increased in 66.6% (4/6), while the urinary gamma-glutamyltransferase value was elevated in 50% (3/6). The renal resistivity index was increased in the right and left kidneys by 66.6% (4/6) of bitches, with no statistical difference between them. It was concluded that the renal resistivity index was a practical and effective method to assist in the diagnosis of acute kidney injury, along with other early markers, such as PCR and urinary GGT.