Epidemiology of systemic inflammatory response syndrome and sepsis in cats hospitalized in a veterinary teaching hospital

Jonathan M. Babyak Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536.

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Claire R. Sharp Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA, 01536.

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Abstract

OBJECTIVE To describe the epidemiology of the systemic inflammatory response syndrome (SIRS) and sepsis in cats hospitalized in a veterinary teaching hospital.

DESIGN Observational study.

ANIMALS 246 client-owned cats.

PROCEDURES During a 3-month period, daily treatment records were evaluated for all hospitalized cats. Information extracted included signalment, temperature, heart rate, respiratory rate, diagnostic test results, diagnosis, duration of hospitalization, and outcome (survival or death). Cats were classified into 1 of 4 disease categories (sepsis [confirmed infection and SIRS], infection [confirmed infection without SIRS], noninfectious SIRS [SIRS without a confirmed infection], and no SIRS [no SIRS or infection]).

RESULTS Of the 246 cats, 26 and 3 were hospitalized 2 and 3 times, respectively; thus, 275 hospitalizations were evaluated. When SIRS was defined as the presence of ≥ 2 of 4 SIRS criteria, 17 cats had sepsis, 16 had infections, 81 had noninfectious SIRS, and 161 were classified in the no SIRS category at hospital admission. The prevalence of sepsis at hospital admission was 6.2 cases/100 admissions. Four cats developed sepsis while hospitalized, resulting in a sepsis incidence rate of 1.5 cases/100 hospital admissions. Four of 17 cats with sepsis at hospital admission and 3 of 4 cats that developed sepsis while hospitalized died or were euthanized, resulting in a mortality rate of 33.3% for septic cats; 239 hospitalizations resulted in survival, 28 resulted in euthanasia, and 8 resulted in death.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that many hospitalized cats have evidence of SIRS and some have sepsis. In cats, sepsis is an important clinical entity with a high mortality rate.

Abstract

OBJECTIVE To describe the epidemiology of the systemic inflammatory response syndrome (SIRS) and sepsis in cats hospitalized in a veterinary teaching hospital.

DESIGN Observational study.

ANIMALS 246 client-owned cats.

PROCEDURES During a 3-month period, daily treatment records were evaluated for all hospitalized cats. Information extracted included signalment, temperature, heart rate, respiratory rate, diagnostic test results, diagnosis, duration of hospitalization, and outcome (survival or death). Cats were classified into 1 of 4 disease categories (sepsis [confirmed infection and SIRS], infection [confirmed infection without SIRS], noninfectious SIRS [SIRS without a confirmed infection], and no SIRS [no SIRS or infection]).

RESULTS Of the 246 cats, 26 and 3 were hospitalized 2 and 3 times, respectively; thus, 275 hospitalizations were evaluated. When SIRS was defined as the presence of ≥ 2 of 4 SIRS criteria, 17 cats had sepsis, 16 had infections, 81 had noninfectious SIRS, and 161 were classified in the no SIRS category at hospital admission. The prevalence of sepsis at hospital admission was 6.2 cases/100 admissions. Four cats developed sepsis while hospitalized, resulting in a sepsis incidence rate of 1.5 cases/100 hospital admissions. Four of 17 cats with sepsis at hospital admission and 3 of 4 cats that developed sepsis while hospitalized died or were euthanized, resulting in a mortality rate of 33.3% for septic cats; 239 hospitalizations resulted in survival, 28 resulted in euthanasia, and 8 resulted in death.

CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that many hospitalized cats have evidence of SIRS and some have sepsis. In cats, sepsis is an important clinical entity with a high mortality rate.

Sepsis refers to the systemic inflammatory response to infection and is an important clinical entity associated with substantial morbidity and mortality in human and veterinary medicine.1–11 The epidemiology of sepsis is well documented in human patients.1,2,11–15 Recognition of the epidemiology of sepsis, severe sepsis, and MODS is important in human emergency medicine and critical care because of the high and increasing prevalence of those conditions and the magnitude of the resources required to treat them.1,2,11 The incidence of hospital-acquired sepsis is also increasing. Although advances in the approach to treatment of sepsis during the past decade have resulted in a decrease in the morbidity and mortality rates associated with that condition in human patients, the burden of sepsis remains profound.1,2,11

Compared with human patients, much less is known about the epidemiology of sepsis in veterinary patients. To our knowledge, studies conducted to describe the epidemiology of sepsis subsequent to all causes in dogs and cats are lacking. Current understanding of the epidemiology of sepsis is based on descriptions (generally retrospective) of specific populations of septic animals, including dogs and cats with abdominal sepsis, pneumonia, pyothorax, and pyometra.3–9,16 Results of a studya conducted to describe the epidemiology of sepsis in dogs hospitalized in the ICU of a veterinary teaching hospital indicate that septic dogs had a longer duration of hospitalization, higher treatment costs, and higher mortality rate, compared with other critically ill dogs.

The literature regarding sepsis in cats is limited; however, a high mortality rate is associated with infectious diseases in cats. Pyothorax,7,8 hepatic abscesses,9 and septic peritonitis4–6 are well described in cats, require high-level care, and are associated with high mortality rates (20% to 80%).3 Although few of the studies cited contain descriptions specific to sepsis, it is likely that most cats with those conditions are septic. Increasing the general awareness of sepsis in cats is imperative to ensure that septic cats receive early, aggressive, and appropriate treatment and to justify prioritization of research funding to investigate this disease syndrome.

The purpose of the study reported here was to describe the epidemiology of SIRS and sepsis in cats hospitalized in a veterinary teaching hospital within a greater population of hospitalized cats. We aimed to determine the prevalence of community-acquired sepsis at hospital admission, the incidence of hospital-associated sepsis in cats, and their associated mortality rates. We hypothesized that cases of both community- and hospital-acquired sepsis would be identified within a hospitalized population of cats and that the mortality rate for septic cats (regardless of whether the sepsis was community acquired or hospital associated) would be significantly higher than that for other hospitalized cats.

Materials and Methods

Surveillance

All patient care, diagnostic testing (eg, bacterial culture, imaging, and serologic evaluation), treatment, and monitoring were determined by the primary clinician in charge of the case. The role of the investigators for the study reported here was merely observational; therefore, the study was exempt from review by the Tufts University Institutional Animal Care and Use Committee and Clinical Studies Review Committee.

Surveillance was performed prospectively on all cats hospitalized at the Foster Hospital for Small Animals at Tufts University over a 3-month period. The hospital manages primary cases as well as secondary and tertiary referrals and has several distinct wards with varying levels of care that parallel the severity of patient illness. Cats that are critically ill are hospitalized in the ICU. Cats with stable illness are hospitalized in an intermediate-care ward, a cat-only ward, or an isolation ward. Cats without substantial illness receive basic medical care in a general-care ward.

A census was conducted daily at 9 pm between August 1, 2010, and October 31, 2010. Cats were included on the census for a given day only if they were present in the hospital at the time the census was taken. Cats that were discharged, died, or were euthanized prior to the census being taken were not included on the census for that day. Cats treated as outpatients were also not included on the census.

Case selection and data collection

The medical records of all cats included on the census were reviewed daily by 1 investigator (JMB). For each cat, data extracted from the daily treatment record included each recorded body temperature, pulse rate, and respiratory rate and CBC findings, if performed. The data were then analyzed to determine the presence or absence of infection, SIRS, and sepsis. The rectal temperature, heart rate, and respiratory rate were evaluated in conjunction with or without CBC results to determine the presence of SIRS. If the rectal temperature, heart rate, and respiratory rate were recorded for a cat more than once during a 24-hour period, each recording was assessed for evidence of SIRS. The definition used to diagnose SIRS was modified slightly from that previously described.3 Briefly, SIRS was defined as the presence of ≥ 2 of 4 predetermined criteria, which included a rectal temperature ≥ 39.7°C (103.5°F) or < 37.8°C (100°F), heart rate ≥ 225 beats/min or ≤ 140 beats/min, respiratory rate ≥ 40 breaths/min, or WBC count ≥ 19,500 WBCs/μL or ≤ 5,000 WBCs/μL or a band neutrophil fraction ≥ 5%. The number of SIRS criteria met for each cat on a given day was recorded, as was the number of cats that met ≥ 2 and ≥ 3 of the 4 SIRS criteria. Cats were evaluated for SIRS at hospital admission and at the time of the daily census only if at least 3 of the 4 variables were evaluated at that time. Sepsis was diagnosed if a cat met the criteria for SIRS diagnosis and had a documented source of infection. Infection was defined as the infiltration of sterile tissue by a microorganism capable of initiating SIRS and was confirmed by culture, cytologic, histologic, or serologic results in combination with clinical signs of disease. For each cat, the presence or absence of sepsis was recorded daily on the basis of the SIRS criteria; however, confirmation of a source of infection did not necessarily occur more than once during hospitalization. Severe sepsis was defined as sepsis associated with the dysfunction of ≥ 1 organ. Multiple organ dysfunction syndrome was defined as the dysfunction of > 1 organ.17 Cats with sepsis were assigned APPLE scores, as described,18 when sufficient clinical data were available. The feline APPLE scores were developed and validated as diagnosis-independent illness severity scores for use in hospitalized cats.18 Both scores are calculated from data obtained during the first 24 hours after hospital admission.18 The APPLEfull score includes assessment of mentation score, temperature, mean arterial pressure, PCV, body cavity fluid score, and lactate, urea, and chloride concentrations. The APPLEfast score includes assessment of mentation score, temperature, mean arterial pressure, PCV, and lactate concentration. Additional problems and diagnoses listed by the primary clinician on the daily treatment sheet for each cat were also recorded. Thus, it was possible for individual cats to have several problems, comorbidities, and diagnoses recorded. All data were recorded on a standardized data collection sheet and subsequently entered into an online database hosted at the Tufts Clinical and Translational Sciences Institute (REDCap). Individual cat data were managed with a commercially available software programb and the online database as described.19 REDCap is a secure, Web-based application designed to support data capture for research studies. It provides an intuitive interface for validated data entry and automated export procedures for data downloads to statistical software packages, among other features.

Statistical analysis

The prevalence of community-acquired sepsis was calculated as the proportion of cats with evidence of SIRS and an infection at the time of hospital admission. The incidence of hospital-associated sepsis was calculated as the proportion of all cats admitted to the hospital that developed SIRS and an infection (regardless of etiology) > 24 hours after hospital admission.

For each cat, the duration of hospitalization was calculated as the time between hospital admission and discharge or death. The outcome for each hospitalization was recorded as survival or death. The data distributions for continuous variables (age and body weight) were assessed for normality by means of visual assessment of histograms. Age and body weight, the only continuous variables reported, were summarized as median (range). Age was not normally distributed; therefore, its association with outcome (survival or death) was assessed by use of the Mann-Whitney U test. The χ2 test or Fisher exact test was used when appropriate to compare mortality rates among disease category groups and between cats with community-acquired sepsis and those with hospital-associated sepsis. All analyses were performed with commercially available statistical software,c and values of P < 0.05 were considered significant.

Results

Cats

During the 3-month observation period, there were 285 instances of cats being admitted to the Foster Hospital for Small Animals, of which 10 were excluded from the study because the only recorded reason for hospitalization was boarding for medical reasons or the cat's rectal temperature, pulse rate, and respiratory rate were not recorded on a daily basis during hospitalization. Thus, 275 hospital admissions were evaluated. Twenty-six cats were hospitalized twice and 3 cats were hospitalized 3 times during the observation period; thus, 246 individual cats were evaluated during the study.

The age was recorded for 236 of the 246 cats, and the median age for those cats was 8.0 years (range, 0.1 to 21.4 years). The study population consisted of 135 (55%) castrated males, 79 (32%) spayed females, 18 (7%) sexually intact females, and 13 (5%) sexually intact males; the sex was not recorded for 1 cat. Breed was recorded for all 246 cats. The most commonly represented breeds were domestic shorthair (n = 147 [59.8%]) and domestic longhair (47 [19.1%]). Other breeds represented included Siamese, Maine Coon, domestic medium-hair, Persian, American Shorthair, Abyssinian, Bengal, Himalayan, Tonkinese, Ragdoll, Birman, Balinese, Norwegian Forest Cat, Devon Rex, Russian Blue, and Scottish Fold. The median duration of hospitalization was 2 days (range, 0 to 26 days).

For each of the 275 hospitalizations evaluated, cats were categorized into 1 of 4 disease categories (sepsis, infection, NSIRS, or no SIRS) on the basis of clinical signs and diagnostic test results recorded in the medical record by the primary clinician. A total of 734 daily treatment records were evaluated for evidence of sepsis and SIRS; however, SIRS was not recorded on the daily treatment sheet of any cat. Only 2 cats were easily identified as septic on the basis of information recorded on their treatment sheets; both of those cats had bacterial peritonitis. The descriptive statistics for cats in each disease category when SIRS was diagnosed on the basis of a cat meeting ≥ 3 of the 4 SIRS criteria (Table 1) or ≥ 2 of the 4 SIRS criteria (Table 2) were summarized. Many of the cats that had an infection but no evidence of SIRS when the more stringent definition (≥ 3 of the 4 SIRS criteria present) for SIRS diagnosis was used had dysfunction of multiple organ systems; therefore, we used the less stringent definition (≥ 2 of the 4 SIRS criteria present) to identify cats with SIRS for the rest of the analyses. The frequency of cats with various clinical signs in each of the 4 disease categories was summarized (Table 3). Many cats had multiple diagnoses or problems listed on their daily treatment sheets (eg, chronic renal failure and hypertrophic cardiomyopathy or vomiting and diarrhea).

Table 1—

Descriptive characteristics for 246 cats (275 hospitalizations) that were hospitalized at a veterinary teaching hospital between August 1 and October 31, 2010, and categorized into 1 of 4 disease categories on the basis of evaluation of daily treatment records and for which SIRS was diagnosed only if a cat met ≥ 3 of the 4 predetermined criteria.

 Disease category
VariableSepsis*InfectionNSIRSNo SIRS
No. of cats62732210
Age (y)4.97 (1.04–14.27)8.70 (0.15–20.88)10.07 (0.18–17.30)8.02 (0.19–21.41)
Sex
   Sexually intact male0329
   Castrated male21319118
   Sexually intact female03115
   Spayed female481066
   Not recorded0002
Body weight (kg)3.9 (2.6–5.1)4.2 (0.3–12.1)4.3 (0.4–14.2)4.7 (0.4–10.1)
Outcome
   Survived4 (66.7)23 (85.2)27 (84.4)185 (88.1)
   Died0 (0)2 (7.4)1 (3.1)5 (2.4)
   Euthanized2 (33.3)2 (7.4)4 (12.5)20 (9.5)

Values represent number of cats, median (range), or number (%) of cats. Two hundred seventy-five hospitalizations for 246 cats were evaluated. Each hospitalization was evaluated independently. Therefore, cats that were hospitalized multiple times may be represented in the same disease category more than once or may be represented in multiple disease categories. The criteria for SIRS included a rectal temperature ≥ 39.7°C (103.5°F) or < 37.8°C (100°F), heart rate ≥ 225 beats/min or ≤ 140 beats/min, respiratory rate ≥ 40 breaths/min, or WBC count ≥ 19,500 WBCs/μL or ≤ 5,000 WBCs/μL or a band neutrophil fraction ≥ 5%. For the purposes of this table, sepsis was defined as a cat with ≥ 3 of the 4 criteria for SIRS and a documented source of infection. Infection was defined as a cat with a documented (as determined by culture, cytologic, histopathologic, or serologic results) infection but no evidence of SIRS. Noninfectious SIRS was defined as a cat that had ≥ 3 of the 4 criteria for SIRS but did not have documented evidence of an infection. Cats that could not be classified in the sepsis, infection, and NSIRS categories were classified in the no SIRS category.

The sepsis category included only cats that were septic at hospital admission (ie, had community-acquired sepsis); it did not include the 4 cats that developed sepsis while hospitalized (ie, hospital-associated sepsis).

Table 2—

Descriptive characteristics for 246 cats (275 hospitalizations) that were hospitalized at a veterinary teaching hospital between August 1 and October 31, 2010, and categorized into 1 of 4 disease categories on the basis of evaluation of daily treatment records and for which SIRS was diagnosed only if the cat met ≥ 2 of the 4 predetermined criteria.

 Disease category
VariableSepsis*InfectionNSIRSNo SIRS
No. of cats171681161
Age (y)9.25 (0.52–16.62)14.09 (5.77–17.62)7.08 (0.19–20.88)8.53 (0.15–21.41)
Sex
   Sexually intact male01310
   Castrated male11115080
   Sexually intact female10414
   Spayed female542455
   Not recorded0002
   Body weight (kg)3.6 (3.0–6.0)4.7 (2.1–10.1)4.9 (0.4–8.5)4.4 (0.3–14.2)
Outcome
   Survived13 (76.5)14 (87.5)70 (86.4)142 (88.2)
   Died2 (11.8)0 (0)3 (3.7)3 (1.9)
   Euthanized2 (11.8)2 (12.5)8 (9.9)16 (9.9)

Sepsis was defined as a cat with ≥ 2 of the 4 criteria for SIRS and a documented source of infection. Noninfectious SIRS was defined as a cat that had ≥ 2 of the 4 criteria for SIRS but did not have documented evidence of an infection.

See Table 1 for remainder of key.

Table 3—

Frequency of cats from Table 2 with various clinical signs or body systems affected in each of the 4 disease categories.

Clinical sign or affected body systemDisease category 
SepsisInfectionNSIRSNo SIRS  
Gastrointestinal tract45133860
Cardiac22193558
Neoplastic10123346
Renal6292845
Lower urinary tract27101534
Neurologic1181626
Lower respiratory tract2112924
Endocrine409922
Upper respiratory tract2431221
Hematologic3010619
Trauma0041216
Hepatobiliary121812
Ophthalmologic201710
Nonspecific problems00369
Musculoskeletal00156
Toxicosis00033
Immune mediated01203
Dermatologic00011

See Table 2 for remainder of key.

SIRS

Eighty-one of 275 (29%) cats had NSIRS on hospital admission. The majority (548/734 [74.6%]) of the daily treatment records contained sufficient data to evaluate the patients for SIRS and sepsis. On the basis of the information contained in those treatment records, the incidence of SIRS was 16.2% (89/548).

Infection

An infection was diagnosed at some point during 33 of the 275 (12%) hospitalizations evaluated. Most of those infections were confirmed by bacterial culture (n = 16) followed by cytologic results (12), histologic results subsequent to necropsy (5), and serologic results (3). More than 1 diagnostic modality was used to confirm the infection in some cats. Overall, 18 unique bacterial species were cultured from the study population. The most frequently isolated species was Escherichia coli (n = 10) followed by unspeciated rods (4), unspeciated cocci (3), Enterococcus spp (2), and Acinetobacter spp, Citrobacter freundii, Klebsiella pneumoniae, Pasteurella spp, Staphylococcus spp, and Streptococcus spp (1 each). Each of 3 bacterial cultures yielded 2 organisms.

Multidrug-resistant bacteria were isolated from 3 cats, and all 3 cats were septic. Those MDR bacteria were cultured from urine, bile, and abdominal fluid samples. Each of those isolates was identified as an MDR strain of E coli that was susceptible to only imipenem, amikacin, and gentamicin. The abdominal fluid sample also yielded an MDR Enterococcus sp that was susceptible to only vancomycin and a synergy of chloramphenicol and gentamicin. Only 2 of those cats survived to be discharged from the hospital.

Other pathogens identified in cats with infections included feline enteric coronavirus resulting in feline infectious peritonitis (n = 1), FIV resulting in immunodeficiency (1), Toxoplasma gondii (2), and Anaplasma spp (1). All cats in which infectious disease was identified by serologic test results also had clinical signs consistent with the disease.

Sepsis

Of the 33 cats with infections, 17 (52%) had at least 2 criteria for SIRS and were therefore considered septic at hospital admission. The most frequent source of sepsis in those cats was peritonitis (n = 6) followed by a urinary tract infection (5), systemic infection (3), respiratory tract infection (2), and hepatobiliary disease (1). The prevalence of community-acquired sepsis was 6.2 cases/100 hospital admissions (ie, 17 cases/275 admissions). Four cats developed sepsis while hospitalized; thus, the incidence of hospital-associated sepsis was 1.5 cases/100 hospital admissions (ie, 4 cases/275 admissions).

Outcome

Of the 275 hospitalizations evaluated, 239 (86.9%) resulted in the cat surviving to be discharged from the hospital, and 36 (13.1%) ended with the death of the patient either from natural causes (n = 8 [2.9%]) or euthanasia (28 [10.2%]; Table 2). Medically or iatrogenically induced adverse events were not identified as the cause of death or euthanasia in any cat. Results of the Mann-Whitney U test indicated that outcome (survival or death) was not significantly associated with age. The mortality rate for cats with sepsis was 33.3% (7/21). Five cats were euthanized and 2 died as a result of severe sepsis or MODS. Specifically, 4 of 17 cats with community-acquired sepsis and 3 of 4 cats with hospital-associated sepsis died or were euthanized; however, the results of a Fisher exact test revealed that the mortality rate for cats with community-acquired sepsis did not differ significantly (P = 0.088) from that for cats with hospital-associated sepsis. The mortality rate for cats with an infection but no evidence of sepsis was 12.5% (2/16). The mortality rates did not differ significantly among the 4 disease categories.

Six cats had evidence of organ dysfunction, of which 5 had severe sepsis. Of the cats with severe sepsis, 4 had hepatic dysfunction, 3 had cardiovascular dysfunction (ie, septic shock), 2 had renal dysfunction, and 2 had coagulation dysfunction. Many of the cats with an infection also had various comorbidities that might have predisposed them to developing an infection such as chronic renal disease (n = 3), feline interstitial cystitis (2), cystic calculi (2), diabetes mellitus (2), neoplasia (2), hyperthyroidism (2), pancreatitis (1), and hypertrophic cardiomyopathy (1).

Only 7 cats with sepsis had sufficient data available for assignment of an APPLE score. The median APPLEfull score was 49 (range, 39 to 62), and the median APPLEfast score was 26 (range, 21 to 39).

Discussion

In the present study, the epidemiology of sepsis and SIRS (regardless of cause) was described for a population of cats hospitalized during a 3-month period in a veterinary teaching hospital. The prevalence and incidence of sepsis in the cats of the present study were similar to the prevalence and incidence of sepsis in dogs.a Interestingly, the prevalence of sepsis in the cats of the present study was similar to that reported in human patients,2 despite the fact that the etiology of sepsis differs between veterinary and human patients. Human patients with sepsis often have respiratory tract infections,1,2 whereas respiratory tract infections were infrequently identified in the septic cats of the present study. Septic peritonitis and urosepsis appeared to be important causes of sepsis in the cats of this study. Human patients with sepsis frequently have comorbidities such as chronic obstructive pulmonary disease, diabetes mellitus, congestive heart failure, HIV infection, hypertension, and cancer, which are not well described in septic cats. Comorbidities commonly diagnosed in the septic cats of the present study included diabetes mellitus, neoplasia, hyperthyroidism, hypertrophic cardiomyopathy, and chronic renal disease.

Recognition of the importance of sepsis as a disease syndrome in human medicine is increasing, as is the prevalence and incidence of sepsis in human patients.1,2 Epidemiologists and physicians suggest that the increasing prevalence and incidence of sepsis in human patients may be the result of an increase in the use of immunosuppressants and organ transplants, HIV infection rates, and antimicrobial resistance. Gram-positive organisms are the most common causative agents of sepsis in human patients,2 whereas gram-negative organisms, particularly E coli, were the most common cause of sepsis in the cats of the present study. Presumably, methicillin-resistant Staphylococcus aureus and similar antimicrobial-resistant gram-positive organisms have an important role in the etiology of sepsis in human patients, which may account for the discrepancy in the primary causative organisms of sepsis between human patients and cats. Additionally, the source of sepsis (eg, septic peritonitis and urosepsis) might explain why gram-negative organisms are commonly isolated from septic cats.

In the present study, we initially used previously proposed guidelines for diagnosing SIRS in cats3 (ie, the presence of ≥ 3 of the 4 SIRS criteria [rectal temperature ≥ 39.7°C or < 37.8°C, heart rate ≥ 225 beats/min or ≤ 140 beats/min, respiratory rate ≥ 40 breaths/min, or WBC count ≥ 19,500 WBCs/μL or ≤ 5,000 WBCs/μL or a band neutrophil fraction ≥ 5%]). Those guidelines were established on the basis of results of an observational study3 in which cats that were presumed to have severe sepsis and died were confirmed to have the disease by means of postmortem examination. The investigators of that study3 proposed those guidelines in an attempt to provide a more objective method for identifying cats with SIRS and improve communication within the veterinary community in a manner analogous to the standardization of definitions for SIRS, sepsis, severe sepsis, and septic shock in human medicine. However, guidelines derived from cats that died from severe sepsis might not be representative for all cats with SIRS. Although we suspect that the proposed guidelines3 are highly specific for cats with severe sepsis, we believe that those guidelines were fairly insensitive for many cats in the study population that had less severe sepsis. Therefore, we adjusted our definition for SIRS to the presence of ≥ 2 of the 4 SIRS criteria, which is the same guideline used to diagnose SIRS in dogs.16 A consensus definition for the diagnosis of SIRS in cats is needed.

We attempted to assign an APPLE score to all cats with an infectious disease to determine whether that score was correlated with the outcome (survival or death). However, because this study was observational, we had to rely solely on the results of diagnostic tests ordered by the primary clinician, and only a small proportion of cats had sufficient data available for APPLE scoring. Subjectively, evaluation of the APPLEfull and APPLEfast scores was not prognostic for outcome in this small study population.

The mortality rate for the septic cats of the present study was similar to that reported for critically ill septic cats and dogs.3–10,16,17,a Comparison of the mortality rate for septic cats with the mortality rate for septic humans is not useful because owners of critically ill cats often choose to euthanize their pet because of financial constraints, quality-of-life issues, or other reasons, which might bias the mortality rate for septic cats. It is difficult to predict whether patients euthanized for unknown reasons would have died in the hospital. Regardless, the mortality rate for septic cats is high, and sepsis should be considered an important cause of death in critically ill cats.

The present study had several limitations. Case selection and observations were conducted at only 1 hospital. However, that hospital manages a wide variety of primary, secondary, and tertiary cases; thus, we feel that the study population was representative of hospitalized cats in the United States. Ideally, a multicenter (and perhaps multinational) study with cats enrolled from both academic and private institutions should be conducted to provide a broader understanding of the epidemiology of sepsis in cats. Another limitation of this study was that the observation period was only 90 days; therefore, seasonal diseases might have been missed or overrepresented in the study population. Additional studies should be performed over a longer period of time to better elucidate the epidemiology of sepsis in cats. Also, cats that were not hospitalized at the veterinary teaching hospital were excluded from this study. Cats with SIRS and sepsis might have been treated as outpatients and cared for by either their owners or primary care veterinarians. Other septic cats might have been excluded from the study if they died or were euthanized prior to the taking of the daily census.

Results of the present study described the epidemiology of SIRS and sepsis in cats that were hospitalized at a veterinary teaching hospital over a 3-month period. The peritoneal space and urogenital system were the most common septic foci, and gram-negative organisms were the most common cause of sepsis in the cats of this study. We believe that these findings support the conclusion that sepsis is an important clinical entity in cats that is associated with a high mortality rate. Thus, further research that focuses on improving the ability of veterinarians to detect sepsis before it becomes severe or MODS develops is warranted.

Acknowledgments

This study was performed in the Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, Mass.

The REDCap database used in this study was made possible through grant support provided to the Tufts Clinical and Translational

Science Institute (grant No. UL1TR001064 from the National Center for Advancing Translational Sciences of the National Institutes of Health).

The authors have no conflicts of interest to declare.

Presented in part as an abstract at the 17th Annual International Veterinary Emergency and Critical Care Symposium, Nashville, Tenn.

The authors thank Shannon Babyak for technical assistance.

ABBREVIATIONS

APPLE

Acute patient physiologic and laboratory evaluation

ICU

Intensive care unit

MDR

Multidrug-resistant

MODS

Multiple organ dysfunction syndrome

NSIRS

Noninfectious systemic inflammatory response syndrome

SIRS

Systemic Inflammatory response syndrome

Footnotes

a.

Guenther-Yenke CL, Torre DM, Maranda LS, et al. Epidemiology of canine sepsis in a veterinary teaching hospital (abstr). J Vet Emerg Crit Care 2007;17:S4–S5.

b.

Excel 2013, Microsoft Corp, Redmond, Wash.

c.

SPSS, version 21.0, IBM Corp, Armonk, NY.

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  • 15. Angus DC, Linde-Zwirble WT, Lidicker J, et al. Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care. Crit Care Med 2001; 29:13031310.

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  • 19. Harris PA, Taylor R, Thielke R, et al. Research electronic data capture (REDCap)—a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform 2009; 42:377381.

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  • 14. Angus DC, Wax RS. Epidemiology of sepsis: an update. Crit Care Med 2001; 29(suppl 1):S109S116.

  • 15. Angus DC, Linde-Zwirble WT, Lidicker J, et al. Epidemiology of severe sepsis in the United States: analysis of incidence, outcome, and associated costs of care. Crit Care Med 2001; 29:13031310.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16. DeClue AE, Osterbur K, Bigio A, et al. Evaluation of serum NT-pCNP as a diagnostic and prognostic biomarker for sepsis in dogs. J Vet Intern Med 2011; 25:453459.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 17. Kenney EM, Rozanski EA, Rush JE, et al. Association between outcome and organ system dysfunction in dogs with sepsis: 114 cases (2003–2007). J Am Vet Med Assoc 2010; 236:8387.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18. Hayes G, Mathews K, Doig G, et al. The Feline Acute Patient Physiologic and Laboratory Evaluation (Feline APPLE) Score: a severity of illness stratification system for hospitalized cats. J Vet Intern Med 2011; 25:2638.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19. Harris PA, Taylor R, Thielke R, et al. Research electronic data capture (REDCap)—a metadata-driven methodology and workflow process for providing translational research informatics support. J Biomed Inform 2009; 42:377381.

    • Crossref
    • Search Google Scholar
    • Export Citation

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