Urinary tract infection in dogs after surgery for intervertebral disk extrusion

Drs. Natasha Olby and colleagues recently published an important prospective study on canine patients surgically treated for disk extrusion.1 They evaluated 25 dogs for urinary tract infections (UTIs) perioperatively and instructed owners to monitor their dogs' urine for three months after surgery. Culture and urinalysis were repeated when the dogs returned for one- and three-month postoperative recheck examinations to determine the prevalence and risk factors for UTIs in these patients.

Ten of these dogs developed a UTI within 14 weeks of surgery, most developing within six weeks. However, only three of the 10 pet owners suspected urinary infection in their dogs at the time of diagnosis. In addition, six of the 10 dogs with positive urine culture results had no evidence of increased white blood cells in their urine.

Sex, breed and level of mobility increased the likelihood for developing UTI in these study dogs. The authors note that risk factors for UTIs in these surgical patients also include indwelling urinary catheters and a failure to empty their bladders effectively. They cite a previous study in which ultrasonographic estimation of bladder volume before and after urination in dogs after intervertebral disk surgery suggested ineffective bladder emptying.2

The authors requested that dog owners in this study monitor their pets' urine with urine dipsticks. These strips revealed abnormalities supporting UTI in only five of the 10 cases that developed a UTI. The owners had been asked to check their pets' urine every other day for one month and then once a week for an additional two months. However, only half of the pet owners succeeded in following the instructions and consistently monitored their pets' urine for more than one month after the surgery. Therefore, the researchers could not determine the efficacy of at-home monitoring and the usefulness of urine dipstick testing for detecting possible UTI.

The authors discussed the possibility that a follow-up urine culture performed beyond three months might be warranted after surgery for intervertebral disk extrusion. They also proposed that prophylactic protocols using agents such as cranberry juice and methenamine hippurate should be investigated in these patients.

The incidence of UTIs was high in this cohort of patients. It is important to note known contributors to the development of UTI, and clinicians treating intervertebral disk disease (or other patients) with corticosteroids should consider periodic urine cultures using samples collected by cystocentesis, regardless of a patient's medical history or the presence of clinical signs.

Dr. Lyman is a graduate of The Ohio State University College of Veterinary Medicine. He completed a formal internship at the Animal Medical Center in New York City. Lyman is a co-author of chapters in the 2000 editions of Kirk's Current Veterinary Therapy XIII and Quick Reference to Veterinary Medicine.

REFERENCES

1. Olby NJ, MacKillop E, Cerda-Gonzale S, et al. Prevalence of urinary tract infection in dogs after surgery for thoracolumbar intervertebral disc extrusion. J Vet Intern Med 2010;24(5):1106-1111.

2. Atalan G, Parkinson TJ, Barr FJ, et al. Urine volume estimations in dogs recovering from intervertebral disc prolapse surgery. Berl Munch Tierarztl Wochenschr 2002;115(7-8):303-305.