Urosepsis in dogs | VETgirl Veterinary Continuing Education Podcasts
In today’s VETgirl online veterinary continuing education podcast, we discuss urosepsis in dogs. Urosepsis simply refers to sepsis that occurs due to an infectious process originating within the urogenital tract. While urosepsis may not be your first differential in the typical septic patient, one study actually found that 35% of septic dogs had an infectious focus identified within either the urinary or genital tract (deLaforcade). There are various origins for urogenital infections that can lead to sepsis, including pyelonephritis, urogenital abscesses, pyometra, infectious prostatitis, septic uroabdomen, tumor necrosis within the urogenital tract, or infections associated with indwelling devices (King, Aronson). Unfortunately, there are few studies characterizing urosepsis in our canine patients. So, Perry et al wanted to evaluate this in a retrospective study entitled Clinical features, outcome, and illness severity scoring in 32 dogs with urosepsis (2017-2018). In this study, the authors evaluated 32 dogs diagnosed with urosepsis. Their objective was to describe the clinical features, outcome, and the utility of an illness severity scoring system in these dogs.
In this study, the investigators reviewed medical records from dogs diagnosed with urosepsis over a 1-year period (2017 to 2018) at a university teaching hospital. They performed a medical record search using several keywords, including pyelonephritis, prostatitis, pyometra, and urosepsis. The authors created a definition of urosepsis that required two key findings. First, dogs must have demonstrated at least two clinical indicators of systemic inflammatory response syndrome (SIRS). SIRS criteria included decreased or elevated body temperature (less than 100.6 F or greater than 102.6 F), elevated heart rate (greater than 120 beats per minute), elevated respiratory rate (greater than 20 breaths per minute), decreased or elevated white blood cell (WBC) counts (less than 6,000/uL or over 16,000/uL), or greater than 3% band neutrophils. In other words, if a dog met at least two of any of those criteria, that was one requirement for inclusion in this study. The second requirement was evidence of a urogenital infection, based on a positive bacterial culture from the urogenital tract. However, if the dog did not have a positive culture, the authors also accepted a combination of cytologic findings, diagnostic imaging, or intraoperative findings. The specific combination of acceptable findings varied for individual diagnoses. For example, if a dog had a distended uterus filled with fluid visualized on ultrasound, and if septic suppurative inflammation was identified on the fluid cytology after collection at surgery, this was sufficient for the investigators to diagnose a pyometra.
The authors extracted thorough information from the medical records. Dogs lacking the necessary information in their records or dogs that did not have a bacterial culture performed were not included. Multidrug resistant (MDR) infections were defined as bacteria resistant to at least one antimicrobial in three or more antimicrobial categories. Furthermore, the authors defined empiric antimicrobial selection as appropriate if at least one of the therapies was susceptible based on culture and sensitivity testing, once those testing results were available. Finally, multiple organ dysfunction syndrome (MODS) was defined as dysfunction of two or more of the six organ systems evaluated, which included the cardiovascular, respiratory, renal, hepatobiliary, gastrointestinal, and hemostatic systems. The authors had various criteria they defined for how to characterize dysfunction in each organ system. Finally, these investigators also employed an illness severity scoring system, known as the APPLE-FAST score. This system is based on a model that incorporates blood glucose levels, serum albumin, platelet counts, plasma lactate, and a mentation score that ranges from 0 (normal) to 4 (unresponsive). The authors note that if either physiologic variables or laboratory values were missing for a patient, they were replaced with a normal value. The authors then calculated a cumulative score, based on this system, that could range from 0 to 50. Fifty represented the most severe illness severity score possible.
Overall, the authors identified 32 eligible cases of canine urosepsis that were included in this study. The median age of dogs was 8 years (range of 2-15 years), and a median weight of 8.9 kg (range 1.5-51.2 kg). The study consisted of 12 spayed females (37.5%), 9 intact females (28.1%), 7 neutered males (21.8%), and 4 intact males (12.5%). Mixed breed dogs were most common (n = 6), followed by Chihuahuas (n = 5), Yorkshire terriers (n = 3), and Dachshund and Pomeranians (n = 2 each). All other breeds were represented only once, and there were a total of 19 breeds included. Interestingly, the most common cause of urosepsis in this population was pyelonephritis, which made up 50% of all cases! This was followed by pyometra (28.1%) and prostatitis (21.8%). Note that some of the dogs in this population did have underlying conditions that could impact the risk of developing a urogenital infection nidus or urosepsis. For instance, recurrent urinary tract infections (UTIs) were reported as a preexisting condition in 11 dogs, and 9 dogs had a history of urolithiasis. It was also noted that 5 dogs were using concurrent corticosteroids, which could be relevant to urosepsis development given the impact on immune function. Other preexisting conditions reported in this population included chronic kidney disease (n = 3), thoracolumbar myelopathy (ambulatory n = 2; nonambulatory n = 1), anatomic abnormalities (n = 3), and hyperadrenocorticism (n = 2). The 3 dogs with anatomic abnormalities suffered from congenital hydronephrosis, ectopic ureter, and a portosystemic shunt, respectively.
Of the 32 dogs enrolled, all had bacterial cultures performed, with a total of 44 cultures performed from urine (n = 24), uterine sources (n = 8), blood (n = 7), or prostatic tissue or fluid (n = 5). Note that no urine samples were collected via pyelocentesis, but all urine samples used for the diagnosis of pyelonephritis were collected via cystocentesis. Eighty-four percent of dogs and 84% of samples submitted were positive for bacterial growth. When looking at sample sources, 100% of prostatic cultures were positive for growth, followed by 87.5% of uterine cultures, 83.3% of urine, and 71.4% of blood. One pyometra case did have a negative uterine culture, but recall that the investigators did have other criteria to make this diagnosis, based on cytology, imaging, or intraoperative findings. Not surprisingly, the most common pathogen identified amongst all samples was Escherichia coli (37.8%), followed by Klebsiella pneumoniae (21.6%) and Staphylococcus pseudintermedius (16.2%). Twelve dogs (37.5%) were already receiving antimicrobial therapy at the time of presentation. Several additional dogs had empiric antimicrobial therapy prescribed while awaiting culture results, and those therapies were deemed appropriate in 63% of cases. Five dogs (18.5%) with positive cultures had an MDR infection identified via culture. Yikes!
Let’s hear about the outcomes for these urosepsis patients. Happily, 87% of dogs survived to discharge in this population! Of the non-survivors, 3 of 4 dogs were euthanized, and the remaining dog passed away naturally. All nine of the dogs with pyometra survived to discharge, followed by 14 of 16 dogs with pyelonephritis, and 5 of 7 dogs with prostatitis. The median hospital stay was 3 days, though it ranged from 1 to 11 days. There was no significant difference identified in survival rates between dogs that had surgery performed versus those with only medical management. Over 40% of dogs had surgical intervention, which included dogs from every disease category. Not surprisingly, the pyometra group was the most highly represented for surgical intervention. Dogs with prostatitis that had a surgical intervention involved drainage of prostatic abscess and omentalization (and possible castration), whereas 2 dogs with pyelonephritis had surgical ureterotomies performed for obstructive uroliths.
Recall that these investigators also evaluated MODS in dogs with urosepsis. In this population, 65.6% of dogs were diagnosed with concurrent MODS. Wow! Of these 21 dogs with a MODS diagnosis, nearly all (20) suffered from gastrointestinal dysfunction. The authors defined gastrointestinal dysfunction as gastric or intestinal ulceration, vomiting, diarrhea, ileus, or intolerance of enteral feeding. Other dogs with MODS demonstrated dysfunction in the hemostatic (18), cardiovascular (18), renal (16), hepatobiliary (14), or respiratory (10) systems. Surprisingly, MODS was not significantly different between the survivor and non-survivor groups, but recall that there were only 4 non-survivors. All 4 of these dogs had MODS, whereas 17 of the 28 survivors were diagnosed with MODS. Of note, dogs that did not survive did have significantly more systems affected than those in the survivor group, and these dogs also had significantly higher illness severity scores.
The authors discuss limitations of this study in depth, which focus largely on the small sample size and retrospective nature of the study. For instance, previous antibiotic administration was not controlled, which could impact culture results, and patient management and diagnostics were not standardized. Additionally, certain causes of urosepsis were not represented in this study population, and since roughly 15% of dogs had a negative culture, it remains possible that some dogs in this population were not truly septic. Finally, owner indication for electing human euthanasia was not documented, meaning it is unclear if or how reasons unrelated to urosepsis influenced these outcomes. This study also recruited dogs from a referral center, which may create a bias towards sicker animals or owners with more financial resources.
So, with those limitations in mind, what can we take away from this VETgirl podcast? Well fortunately, the overall mortality rate was low, as 87% of patients survived to discharge. This is excellent news! MODS was common in this population, so remember to include a thorough systemic assessment in these patients. The nonsurvivors had more organ systems demonstrating dysfunction, which can help guide prognostic expectations in these challenging cases. Also recall that pyelonephritis was the most common cause of urosepsis in this particular population, but do not forget to look for other sources. Note that nearly 40% of empiric antibiotics prescribed in this study were deemed not appropriate once culture results became available. Therefore, it is important to perform bacterial cultures to help guide your treatment plans, to use those cultures to reassess any previous empiric therapy selections, and to continue to be responsible antimicrobial stewards. This study provides valuable information for owners and clinicians when managing canine urosepsis, and we hope to see more studies that expand upon these findings in the future!
References
1. Perry KM, Lynch AM, Caudill A, et al. Clinical features, outcome, and illness severity scoring in 32 dogs with urosepsis (2017-2018). J Vet Emerg Crit Care 2022 Mar;32(2):236-242.
2. deLaforcade AM, Freeman LM, Shaw SP, et al. Hemostatic changes in dogs with naturally occurring sepsis. J Vet Intern Med 2003;17(5):674- 679.
3. King LG. Postoperative complications and prognostic indicators in dogs and cats with septic peritonitis: 23 cases (1989-1992). J Am Vet Med Assoc 1994;204(3):407-414.
4. Aronson LR. Urosepsis. In: Silverstein DC, Hopper K, eds. Small Animal Critical Care Medicine. 2nd ed. Elsevier; 2015:521-527.
Abbreviations
WBC – White blood cell
MDR – Multidrug resistant
MODS – Multiple organ dysfunction syndrome
SIRS – Systemic inflammatory response syndrome
UTI – Urinary tract infection
Today’s VETgirl podcast is sponsored by Royal Canin. Recommend multifunction Royal Canin Urinary SO® + Calm complete and balanced adult cat food to help support a healthy urinary tract while providing calming nutrients for cats facing stress. Learn more at my.royalcanin.com.
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