February 07, 2018

Bacteriuria Versus Urinary Tract Infection in Paraplegic Dogs

How common are bacteriuria and urinary tract infection in chronically paralyzed dogs, and how does bacteriuria affect survival rate in these patients?
By Natalie Stilwell, DVM, MS, PhD
Urinary tract infection (UTI) is a common concern in chronically paralyzed dogs due to impaired storage and voiding ability of the lower urinary tract. Left untreated, UTI can have serious complications, including pyelonephritis, septicemia, and death.

Current criteria for diagnosing UTI in dogs include a quantitative aerobic urine culture with >105 CFU/mL bacteria and the presence of at least 1 of the following clinical signs: inappropriate urination, dysuria, hematuria, stranguria, pollakiuria, or malodorous urine. UTI can be more difficult to diagnose in the chronically paralyzed dog, as the patient lacks normal sensory perception and urine voiding function. Asymptomatic bacteriuria is also common in paraplegic dogs and is typically not treated with antibiotics.

The authors of a recently published retrospective study examined the frequency of bacteriuria in dogs with chronic paraplegia. The study identified the most common bacterial organisms and clinical signs associated with bacteriuria, as well as overall survival of paralyzed patients.  

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Analyses
Investigators examined the veterinary records from dogs suffering from chronic paraplegia for at least 3 months. Each dog had at least 1 documented urine culture and sensitivity test.

Results
Twenty-three female and 24 male dogs were included in the study. The average age of onset of paraplegia was 4.1 years, and the average duration of paraplegia was 5.2 years. No trends were observed between frequency of bacteriuria and age of paraplegia onset, duration of paraplegia, or survival time. Frequency of bacteriuria was statistically similar between male and female dogs.

Thirty-five (75%) dogs had at least 1 recorded episode of bacteriuria, as indicated by a quantitative aerobic urine culture containing >105 CFU/mL bacteria. Thirteen (28%) of the paraplegic dogs experienced recurrent bacteriuria. Of 251 cultures obtained from paraplegic dogs, 141 (56.2%) were positive.

Fourteen bacterial species were identified in positive cultures, and most positive cultures contained either Escherichia coli (34.8%) or polymicrobial growth (15.6%). Sensitivity tests indicated that 9.9% (14/141) of positive cultures were antibiotic-resistant. Most resistant cultures were identified as enteric bacteria and were associated with recurrent bacteriuria.

The only clinical sign found to be highly associated with bacteriuria was pyuria (35/54 positive cultures). In contrast, fever was only present in 2 of 33 cases of bacteriuria, and cloudy urine was common in both positive and negative culture samples. Malodorous urine was noted for 44 of 251 urine samples, 38 of which yielded bacterial growth.

The authors emphasized that veterinary records often lacked important information used to distinguish bacteriuria from UTI, including physical examination findings and urinary history. They emphasized that a physical exam should be performed any time a urinary culture is obtained from a paraplegic canine patient.

Take-home Message
Bacteriuria and recurrent bacteriuria are common in paralyzed dogs. However, the clinical signs commonly used to differentiate UTI from bacteriuria in paralyzed human patients, such as fever and malodorous urine, occur inconsistently in the dog. Further study is needed to establish specific criteria for diagnosing and treating bacteriuria in the paraplegic canine patient.

 
Dr. Stilwell is a medical writer and aquatic animal veterinarian in Athens, Georgia. After receiving her DVM from Auburn University, she completed an MS degree in Fisheries and Aquatic Sciences, followed by a PhD degree in Veterinary Medical Sciences, at the University of Florida.

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