Department of Medicine & Epidemiology, University of California-Davis, Davis, CA, USA
The International Society for Companion Animal Infectious Diseases (ISCAID) Antimicrobial Guidelines Working Group was formed to develop guidelines for antimicrobial drug use in dogs and cats, because of concerns that antimicrobial drug resistance has dramatically increased in prevalence among isolates from dogs and cats in the last decade. The founding members of the ISCAID Working Group are Scott Weese, Joseph Blondeau, Dawn Boothe, Edward Breitschwerdt, Luca Guardabassi, Andrew Hillier, Michael Lappin, David Lloyd, Mark Papich, Shelley Rankin, Jane Sykes, and John Turnidge. Input has also been obtained from panels of Diplomates of relevant specialty groups. It should be noted that members of the working group receive support from a variety of industry groups that provide funding for honoraria and research.
Guidelines for treatment of urinary tract disease in dogs and cats were published in 2011 and are available as open access documents for any individual to download (www.iscaid.org). During the course of guideline development, it became clear that there is a significant lack of objective, published information. Accordingly, recommendations are based on available data, whenever present, along with expert opinion, considering principles of infectious diseases, antimicrobial treatment, antimicrobial resistance, pharmacology, and internal medicine. Clinical trials that evaluate antimicrobial drug regimes for bacterial infections in dogs and cats are encouraged. In 2016 and 2017, the Working group began the process of revising guidelines for urinary tract infections based on additional evidence and peer expert input. As with the Respiratory Guidelines development process, Working Group members will be voting on recommendations and a Level of Agreement presented for each statement. Selected recommendations from previously published guidelines and the update are presented below.
Definition: Sporadic bacterial infection of the bladder in an otherwise healthy individual with normal urinary tract anatomy and function.
A clinically significant infection implies the presence of dysuria, pollakiuria, and/or stranguria. Diagnosis of UTI cannot be made on the basis of clinical signs alone.
Complete urinalysis should be performed for all cases and quantitative aerobic C&S testing is encouraged. Free-catch samples should not be used. For cystocentesis specimens, counts ≥103 CFU/ml indicate UTI. For catheterized specimens, counts ≥104 in males and ≥105 CFU/ml in females are significant. Recommendations for initial treatment are amoxicillin (11–15 mg/kg PO q12h) or trimethoprim-sulfonamide (15 mg/kg PO q12h). If C&S testing reveals a resistant isolate and there is a lack of clinical response, treatment should be changed to an appropriate antimicrobial drug. Although treatment has been recommended in the past for 7 to 14 days, recent research suggests 3–5 days may be more appropriate. There is no evidence that intra- or post-treatment urinalysis or urine culture is indicated in the absence of ongoing clinical signs of UTI.
Recurrent Bacterial UTI
Definition: Recurrent UTls are defined by the presence of 3 or more episodes of UTI during a 12-month period or 2 or more infections within a 6 month period. Efforts should be made to identify the underlying cause; consider referral. Treatment should be based on the results of C&S testing, with initial empiric therapy following the recommendations for sporadic bacterial cystitis. Although 4 weeks has been recommended for treatment, shorter durations are likely to be recommended in the future, with a focus on clinical cure rather than microbiological cure. There is insufficient evidence to recommend “pulse” or chronic low-dose treatment, urinary antiseptics, and nutritional supplements such as cranberry juice extract for prevention of UTls.
Definition: presence of bacteria in the urine as determined by positive bacterial culture, in the absence of clinical signs of UTI. Treatment may not be necessary, but could be considered if there is a high risk of ascending or systemic infection (e.g., patients with underlying renal disease).
Proper aseptic placement and maintenance is critical. Open collection systems should not be used. Clinical signs of lower UTI or pyelonephritis absent: no culture or treatment indicated. The duration of catheterization should be as short as possible. Catheter removal is not necessary in the presence of subclinical bacteriuria. There is no indication for routine use of prophylactic antimicrobials after the catheter is removed.
If clinical signs of UTI or fever are present: perform a culture after replacement of the urinary catheter with a new catheter. Several ml of urine should be removed to clear the catheter before a specimen is obtained for culture. Alternatively, remove the catheter and perform a cystocentesis. Culture from the collection bag and culture of the catheter tip after removal are not recommended. Treatment should follow the guidelines for sporadic bacterial cystitis, and is more likely to be successful after catheter removal.
C&S testing should always be performed. Treatment should be initiated while awaiting culture results, using antimicrobials effective against gram-negative Enterobacteriaceae. A fluoroquinolone is a reasonable first choice, after which treatment should be based on C&S results. If combination treatment was used initially and C&S results indicate that both drugs are not required, the spectrum should be narrowed. Treatment for 4 weeks has been recommended, but it is likely that shorter durations of treatment (10–14 days) may be effective. Culture is recommended 1–2 weeks after treatment is discontinued, together with a physical examination and assessment of azotemia, but the possibility of subclinical bacteriuria should be considered when interpreting culture results.
Urological Surgery, Minimally Invasive Urological Procedures and Urologic Implants
Bacterial culture of urine collected by cystocentesis is indicated prior to cystoscopic procedures or laparoscopic or open urologic surgery. If bacteriuria is identified, treatment based on susceptibility result is indicated for 3–5 days immediately before the procedure to reduce bacterial counts. Peri-operative antimicrobial prophylaxis should be considered for procedures that involve stone manipulation or open surgical procedures that involve the urinary tract. When antimicrobial prophylaxis is indicated, the antimicrobial(s) should be administered intravenously within 60 minutes of the procedure and be re-dosed intra-operatively after 2 halflives of the drug have passed (when applicable), in order to target the time that bacterial invasion is most likely to occur. Typically, this is until wound closure or completion of an endoscopic procedure. An appropriate choice for peri-operative prophylaxis is a first- or second-generation cephalosporin. In the absence of complicating factors or infection, peri-operative prophylaxis should not continue for greater than 24h.
Medical Dissolution of Struvite Urolithiasis
Urine culture should be performed in all cases where urolithiasis is identified. Culture of surgically-removed uroliths can be considered, but the clinical relevance of results is unclear. If evidence of bacterial cystitis is present, antimicrobial drug selection should be approached as per sporadic cystitis. At least seven days of treatment is suggested for animals with urolithiasis and concurrent bacterial cystitis. The need for further treatment is unclear. Limited data are available regarding the need for antimicrobials during dietary dissolution of struvite uroliths. Low level data suggest that treatment may not be required; therefore, antimicrobial treatment during the dissolution period is not recommended in animals that do not have evidence of ongoing bacterial cystitis. Bacterial culture can be considered during dietary dissolution period in the absence of clinical signs of cystitis. If a urease-producing bacterial species is identified, treatment can be justified. Urine culture after completion of medical urolith dissolution is not recommended in the absence of clinical signs of lower urinary tract disease. Confirmation of elimination of uroliths through diagnostic imaging and investigation of predisposing factors for cystitis is important.
Empirical treatment for bacterial prostatitis should target Enterobacteriaceae. Administration of a veterinary fluoroquinolone such as enrofloxacin should be considered while awaiting culture and susceptibility testing results. Trimethoprim-sulfonamide can be considered but is not recommended where a fluoroquinolone can be used because of the greater risk of adverse effects with the typical duration of treatment. Limited data are available to guide duration of treatment. Four weeks is typically recommended for acute prostatitis, with 4–6 weeks for chronic disease. Shorter durations might be effective in dogs with acute prostatitis that are castrated and where there is rapid clinical response. A longer duration of treatment may be required in some chronic cases, particularly when abscessation is present or when castration is not performed. Castration should be recommended in dogs that are not intended for breeding. Poor initial response to therapy should lead to re-assessment of the diagnosis and if prostatitis is still suspected, consideration of collection of ultrasound-guided fine needle aspirate of prostatic cyst fluid or prostatic tissue core biopsy for culture and cytology or histopathology. Prostatic abscesses should be drained because of the low likelihood of resolution with medical treatment alone. If necessary, surgical drainage should be performed after culture results are available, whenever possible, to facilitate proper peri-operative antimicrobial therapy.
1. Weese JS, Blondeau JM, Boothe D, et al. Antimicrobial use guidelines for treatment of urinary tract disease in dogs and cats: antimicrobial guidelines working group of the International Society for Companion Animal Infectious Diseases. Vet Med Int. 2011; Epub Jun 27.