A fresh look at identifying sepsis in cats - Veterinary Medicine
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A fresh look at identifying sepsis in cats
New criteria have made the diagnosis of sepsis more specific. However, most of the studies have evaluated people. Find out how these new criteria relate to cats—and how to treat septic cats once you've identified them.



In a recent study evaluating the safety and efficacy of activated protein C in people with severe sepsis, the respiratory tract was the source of sepsis in more than half of the 1,690 patients.7 The gastrointestinal and urinary tracts were the other major sources, representing 20% and 10% of cases, respectively. No studies in companion animals report the cause of sepsis or the outcome in large populations.

In a study of severe sepsis in 29 cats, the most common causes of sepsis were pyothorax (24%), septic peritonitis (14%), endocarditis (14%), pyelonephritis (7%), osteomyelitis (3%), pyometra (3%), and bite wounds (3%).8 While there is no comparable study in dogs, the most commonly reported cause of sepsis is peritonitis.9-11 Reproductive organs (uterus, prostate) are also common sources of sepsis in dogs. In cats, pyothorax frequently occurs as an extension of pneumonia12 ; however, it appears that pyothorax may lead to sepsis more frequently than pneumonia leads to sepsis.8

Direct comparison of the response of cats to sepsis vs. the response of dogs is challenging. Few studies have provided the same diagnostic criteria or reflect the same basic population; however, several generalizations can be made regarding cats with sepsis. The first is that cats are more likely to have a hypodynamic response. In other words, they are likely to be hypothermic, pale, and bradycardic (heart rate < 140 beats/min; Table 1).8 Anemia is a common finding in septic cats.5,8 Hypoalbuminemia is common in septic dogs and cats.5,8,10

Most cases of sepsis are from bacteria of enteric origin, predominantly Escherichia coli. However, in cases of feline pyothorax, Pasteurella and Clostridium species predominate,4 and in the limited reports of endocarditis in cats, gram-positive bacteria and Bartonella species were the reported causes.13

In some cases of sepsis in cats, the source of infection is readily apparent, such as in cats with severe bite wounds, penetrating trauma, or infected wounds. However, in other cases, determining the source of infection can be more challenging. Potential sources of infection in cats include pneumonia, pyothorax, septic peritonitis, septic pancreatitis, pyelonephritis, bacteremia secondary to severe gastrointestinal disease, pyometra, hepatic abscesses, endocarditis, or meningitis.

In dogs and cats with septic peritonitis, the gastrointestinal tract is the most likely source of infection; however, there are some distinct differences. Cats are more likely to have intestinal neoplasia as a cause of peritonitis.5 Dogs appear more likely than cats to have gastric rupture (ulcers, gastric dilatation-volvulus).10,11 The reproductive organs are a more likely source of infection in dogs than in cats. Cats are more likely to have an undiagnosed source of peritonitis than dogs are5 ; however, a recent study of septic peritonitis in cats reported that trauma and the subsequent disruption of the gastrointestinal tract was an important cause.14


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