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Pyelonephritis is a bacterial infection of the renal pelvis, the funnel-like part of the ureter in the dog's kidney.
Normally, if pyelonephritis takes place, it is due to an impairment of the dog's defenses: ureteral movement, blood supply to the kidneys, or the flap valves found between the kidney and ureters.
Pyelonephritis can also develop due to kidney stones or when microbes climb upward, spreading a lower urinary tract infection to the upper urinary tract. Blockage of an infected kidney or ureter can lead to more serious complications: sepsis, a bacterial infection of the blood; or urosepsis, an infection of the blood resulting from decomposed urine being forced into the bloodstream.
The condition described in this medical article can affect both dogs and cats. If you would like to learn how pyelonephritis affects cats, please visit this page in the PetMD health library.
Escherichia coli and Staphylococcus spp. are the most common bacterial causes for infection. Other bacteria which may lead to pyelonephritis include Proteus, Streptococcus, Klebsiella, Enterobacter, and Pseudomonas spp., which commonly infect the lower urinary tract, but which may ascend into the cat's upper urinary tract.
Your veterinarian will perform a complete physical exam on your dog, including a blood chemical profile, a complete blood count, a urinalysis and an electrolyte panel.
If your dog has a lower urinary tract infection already, this highly predisposes it to pyelonephritis. Your veterinarian may perform an ultrasound, or an X-ray of the urinary tract (excretory urography) to differentiate between a lower urinary tract infection and pyelonephritis.
Definitive diagnosis requires urine cultures obtained from the renal pelvis (funnel-like part of the ureter in the kidney) or parenchyma, or, as a last resort, histopathology from a renal biopsy.
A fluid sample from the renal pelvis, using a procedure called pyelocentesis, can also be performed through the skin (percutaneously) using ultrasound guidance, or during exploratory surgery. A specimen for culture might also be obtained from the renal pelvis. If the dog has kidney stones, an incision into the dog's kidney (a nephrotomy) will be necessary to acquire a sample of the mineral.
Antibiotics can be prescribed initially, and will be changed, if necessary, according to the results of the dog's urine culture and sensitivity profile. Surgery should be considered if your dog has pyelonephritis in the upper urinary tract, or if the urinary tract is obstructed.
If kidney stones are present, surgery should be performed to remove them, unless your veterinarian finds that the stones can be removed by dissolving them via a diet change (this only works for struvite kidney stones), or by using shock wave therapy to fragment them and allow them to pass from the animal's body.
To ensure progress is being made, your veterinarian will schedule a follow-up appointment and perform a urinalysis and urine cultures on your dog one week after antibiotic treatment has begun. These tests are then repeated once the antibiotic course has ended -- at one and at four weeks -- to make certain the dog is not in remission.
A medical condition; the contamination of a living thing by a harmful type of bacteria
The tubular shaft found between the kidneys and the bladder
Also referred to as a UTI; a medical condition of the urinary tract and system in which the cells are damaged by microorganisms.
The disappearance of the signs and symptoms of a particular disease; this is often used in association with cancer
An in-depth examination of the properties of urine; used to determine the presence or absence of illness
A medical condition involving excessive thirst
The term for plant life or animal life that is microscopic
The elements of function in a given tissue or organ
The term for the hip and related area
The process of removing tissue to examine it, usually for medical reasons.