A kidney infection in dogs – known medically as pyelonephritis – can be a serious issue for your canine companion. 

The kidneys function to remove toxins from the blood and excrete waste in the form of urine. When the kidneys are infected, these important functions can become compromised. 

Identifying and treating a kidney infection quickly is essential to ensure a good outcome for your dog.

What Is a Kidney Infection?

Kidney infections in dogs are most commonly caused by bacteria. This most commonly occurs due to a urinary tract infection that then ascends the ureters – the tubes that connect the kidney to the bladder – and into the kidney. 

Kidney infections can come on suddenly (acute) or be gradual and long lasting (chronic). Left untreated, kidney infections can lead to kidney failure and sepsis.

What Causes Kidney Infections in Dogs?

Kidney infections typically start as a bacterial infection in the lower urinary tract – the bladder and urethra – which then ascends to the kidneys. E. coli is the most common bacteria causing kidney infections, but other bacteria such as Staphylococcus, Streptococcus, and Enterococcus spp. have also been isolated from dogs with kidney infections. 

Dogs with urinary tract abnormalities or systemic disorders are at higher risk of developing urinary tract infections, and thus, kidney infections. 

Factors that can predispose a dog to kidney infection include:

Congenital anatomical abnormalities

• Bladder stones or kidney stones
• Ureter obstruction
• Urethral catheterizations
• Tumors of the urinary tract
• Kidney disease
• Prostatitis
• Urinary disorders
• Diabetes mellitus
• Hyperadrenocorticism (Cushing’s Disease)
• Hyperthyroidism
• Immunosuppression

If your dog has one or more of these predisposing factors, it is especially important to keep an eye out for symptoms of urinary tract infection and kidney infection and seek treatment right away if these signs occur.

Dog Kidney Infection Symptoms

Symptoms of kidney infections in dogs can vary widely depending on the type of bacteria present and whether the infection is acute or chronic. 

Some dogs with kidney infections are asymptomatic. Others have symptoms of a lower urinary tract infection or can even be critically ill and develop kidney failure and sepsis. 

Symptoms of kidney infections in dogs can include:

• Blood in the urine
• Painful urination
• Inappropriate urination (such as accidents in the house)
• Urinating frequent small volumes
• Abdominal pain
• Urinating more frequently
• Urinating larger volumes than usual
• Drinking more than usual
• Dehydration
• Fever
• Loss of appetite
• Weight loss
• Lethargy
• Vomiting

If your dog exhibits any of these symptoms, see your veterinarian right away. It is especially important to keep an eye out for symptoms of kidney infection if your dog has a history of recurrent urinary tract infections, chronic kidney disease, bladder or kidney stones, or other chronic conditions that may predispose them to kidney infection.

Diagnosing Kidney Infections in Dogs

To diagnose a kidney infection, your veterinarian may recommend some or all of the following tests:

Physical Examination. Your veterinarian will perform a comprehensive head-to-tail physical examination on your dog.  Abnormalities noted on physical examination may include fever, dehydration, abdominal pain, and weight loss.

Urinalysis. Your veterinarian will likely recommend submitting a urine sample from your dog for analysis. This allows your veterinarian to look for signs of infection such as bacteria and white blood cells in the urine.

Blood Work. A complete blood count and biochemistry panel may be recommended to evaluate your dog’s kidney function and to rule out other possible causes for your dog’s symptoms. In some cases of kidney infection, blood work is normal. In others, signs of renal failure may be present.

Radiographs (X-rays). Your veterinarian may recommend abdominal radiographs (x-rays) to visualize your dog’s urinary tract and assess for changes such as enlarged kidneys, stones, or an enlarged prostate.

Ultrasound. Ultrasound allows your veterinarian to assess the size and shape of your dog’s kidneys, as well as the appearance of the layers of the kidney tissues. The changes noted on ultrasound can be diagnostic for kidney infection in many patients.

Culture. Collecting a sample of urine directly from the kidney and submitting it to a laboratory for culture is the gold standard for diagnosing a kidney infection in dogs. This must be performed either using an ultrasound or by performing surgery. The sample is then grown in the laboratory and the bacterial type identified and used for sensitivity testing.

Sensitivity Testing. Bacteria grown from the dog’s culture sample are tested using several different antibiotic types to determine which types of antibiotics the bacteria are susceptible to. This is used to guide treatment choices and ensure the best outcomes for your dog.

Dog Kidney Infection Treatment

The treatment for a kidney infection in dogs is antibiotics. The antibiotic should ideally be chosen based on culture and sensitivity results. Dogs with kidney infections typically require antibiotic treatment for 10-14 days, but longer treatments may be recommended for some canines.

In addition to antibiotics, supportive care may be prescribed, particularly for dogs with acute infections or those with renal failure. Supportive care may include hospitalization for intravenous (IV) fluids, pain control, and antiemetic medications.

Many dogs with a kidney infection have other underlying medical conditions that predisposed them to developing a kidney infection. These underlying conditions must also be addressed.

Following completion of antibiotic therapy, it is recommended that a recheck urinalysis, urine culture, and blood work be performed to ensure the infection has been cleared and kidney values have returned to normal. A urine culture should be performed at 1, 3, and 6 months following treatment to monitor for recurrence of the infection.

Cost to Treat Kidney Infection in Dogs

The cost to treat kidney infection in dogs can vary widely depending on the severity of the infection. For many dogs, antibiotics may be the only treatment necessary to address this condition. Depending on the type of antibiotic needed, the size of the dog, and the duration of treatment, pet owners should expect to pay $50-$200 for this treatment. 

In severe cases requiring hospitalization and supportive care, pet owners should expect to pay significantly more for treatment, with costs quickly adding up over $2,000.

How to Prevent Dog Kidney Infections

In general, kidney infections can’t be prevented. But there are some steps you can take to reduce your dog’s risk of developing a kidney infection, such as identifying and treating urinary tract infections early, before they lead to kidney infections. 

It is also important to address any underlying conditions your dog may have, such as diabetes mellitus or Cushing’s disease, as these may predispose your dog to developing a kidney infection.