Pyelonephritis of the Kidneys in Dogs

Pyelonephritis is a bacterial infection in the upper urinary tract involving kidneys and ureters. This infection occurs when the bacteria move from the urinary tract or the urethra up into the kidneys. If your dog already has an obstruction in the urethra, in the forms of stones or other blockages, the risk of your dog getting Pyelonephritis of the kidneys is higher. This is a treatable condition. However, if it is left untreated, it can lead to complications, including a bacterial infection in your dog’s bloodstream. Generally, the symptoms are noticeable and identifiable, making it easy to begin treatment.

Symptoms of Pyelonephritis of the Kidneys in Dogs

There are a few visible symptoms of Pyelonephritis, and it is essential that you consult your dog’s vet immediately. The symptoms include

  • Moderate to severe side pain
  • Fever
  • Lethargy or malaise
  • Vomiting
  • Loss of appetite
  • Extreme thirst
  • Frequent and excessive urination
  • Bloody urine
  • Foul smell in the urine
  • Discolouration of the urine
  • Pain in the lower back
  • Incontinence

There are a few similar symptoms for other health conditions in dogs. The Vet will need to rule out other conditions such as Cystitis, obstruction in the ureter, peritonitis, Nephrolithiasis, and Hydronephrosis.

Causes of Pyelonephritis of the Kidneys in Dogs

Infections in the kidneys can occur spontaneously; however, it is more common when there is a pre-existing condition such as chronic kidney disorder, bladder infection, kidney stones, and urinary tract blockage. Specifically, the causes of Pyelonephritis of the kidneys in dogs are due to bacterial infection. Escherichia coli and Staphylococcus spp. are common bacteria that leads to infection Causes of this bacterial infection are due to the following:

  • Age can be a factor, i.e., an older dog or a very young dog.
  • A weak immune system
  • Specific kidney dysfunctions
  • Water imbalance in the urine

Fungal infections (rarely) and a few other diseases may increase chances of Pyelonephritis of the kidneys in dogs. Diseases such as renal dysplasia, an abnormality in kidneys from birth, and ectopic ulcers where the ureters are not connected properly to the bladder, Diabetes, Steroids, Cushing’s disease, Bladder stones, catheterization of the urethra may increase the risk of Pyelonephritis in your dog.

Diagnosis of Pyelonephritis of the Kidneys in Dogs

The diagnosis will begin with a thorough physical exam and will order tests for complete blood count (CBC), blood chemical profile, urinalysis, and an electrolyte panel. Make sure that you carry the dog’s medical history and a record of the symptoms and their onset.

If your dog is already affected by an infection of the lower urinary tract, your dog is predisposed to Pyelonephritis. The Vet may also require an X-ray or ultrasound of the urinary tract to differentiate Pyelonephritis from a lower urinary tract infection.

Urine cultures taken from the renal pelvis or parenchyma will offer a more definitive diagnosis. Additionally, the vet may also order histopathology from the renal biopsy.

Further, Pyelocentesis, a procedure that is performed through the skin guided by ultrasound, will be used to take a fluid sample from the renal pelvis. A specimen for further culture study may be taken from the renal pelvis. If your dog has kidney stones, the vet will make an incision into the kidney – nephrostomy – to get the mineral sample. 

Treatment of Pyelonephritis of the Kidneys in Dogs

The treatment for Pyelonephritis of your dog’s kidneys will be effective as long as the infection is caught at its onset and is diagnosed accurately. There are two approaches to treat this condition, depending on the severity of the infection. 

Use of antibiotics

The Vet will prescribe antibiotics to fight the infection, and the dosage will often be for around four to six weeks. It is essential that the course of the antibiotics is completed as advised by the Vet. If the Pyelonephritis is chronic, antibiotics may not be as effective because they will not be able to penetrate through the functional tissues of your dog’s kidney. 


If the Pyelonephritis is severe and is at an advanced stage, the kidney may have stopped functioning. The affected kidney will have to be removed surgically. 

IV floods may be part of the treatment as your dog may become dehydrated. The Vet may also treat any underlying cause for Pyelonephritis, including blockages or stones. 

Recovery from Pyelonephritis of the Kidneys in Dogs

Generally, the prognosis for Pyelonephritis is good, the critical point being that the diagnosis is made accurately and the treatment is begun immediately. In some cases, the damage to kidneys can be permanent because they may not have the ability to repair themselves. Your dog will need to be monitored carefully during the recovery once the treatment is completed. There is always the risk of the infection recurring. 

Keeping your dog safe and protected during recovery will help quicken the process. Meticulous records of the entire process, from symptoms to treatment, will also keep you informed of possibilities of future infections. 

Make sure that you keep up with the regularly scheduled visits with the Vet. The follow-up visits will include urinalysis and urine culture a week after beginning on the antibiotics. These tests will be repeated at the end of the antibiotics’ course to ensure that your dog is not in remission. 

Follow the vet’s instructions on caring for your pet at home. If the treatment involved surgery and a kidney has been removed, the at-home care would have to be more thorough and for an extended period. 


The information contained in VOSD Vet Advice™ is not intended nor implied to be a substitute for professional medical action which is provided by your vet. You assume full responsibility for how you choose to use this information. For any emergency situation related to a dog’s health, please visit the nearest veterinary clinic.

Do you find this information useful? For more medical advice, visit the VOSD website.