Sepsis in Cats: Causes, Symptoms and Treatment

Sepsis is the systemic inflammatory response to infection and is defined as the presence of SIRS (extreme systemic inflammatory response) in addition to the infection which can cause organ dysfunction. Any organ can be affected which includes the heart, liver, lungs, and kidneys. This can affect respiration, blood pressure, kidney function, blood clotting and oxygenation of the tissues.

Sepsis is less common in cats than in dogs. There does not appear to be a breed or sex predilection in cats.

SIRS was first introduced in 1992 by the American College of Chest Physicians.

Definitions relating to sepsis

  • MODS, which stands for multi-organ dysfunction system.
  • Severe sepsis, which includes organ dysfunction and low blood pressure.
  • Septic shock, which is severe sepsis plus low blood pressure (hypotension) that is unresponsive to fluid therapy.

Common infections which can trigger sepsis include:

  • Pyothorax (pus in the pleural space in the chest)
  • Septic peritonitis (infection of the peritoneal cavity)
  • Bacteremia (bacteria in the blood) secondary to gastrointestinal tract disease
  • Pneumonia
  • Pyometra (infection of the uterus)
  • Endocarditis ( infection of the endocardium, the inner lining of the heart chambers and heart valves)
  • Pyelonephritis (kidney infection)
  • Osteomyelitis (bone infection)
  • Bite wounds
  • Salmonellosis

Clinical signs

Additional symptoms may be present depending on the underlying cause. For example, a cat with pyometra (infected uterus) may have foul-smelling discharge.


The veterinarian will perform a complete physical examination of the cat and obtain a medical history from you.

The following criteria have been proposed for cats with SIRS.

  • Temperature Hypothermia < 100°F or fever > 103.5°F
  • Heart rate Bradycardia (slower than normal heart rate) < 140 beats/minute > or Tachycardia (elevated heart rate) >225
  • Tachypnea (elevated respiratory rate) > 40 breaths/minute
  • White blood cell count > 19,500, < 5,000, or > 5% bands

Diagnostic workup:

  • Baseline tests: Complete blood count, biochemical profile and urinalysis to look for hypoalbuminemia (low blood albumin levels), anemia (low red blood cells), glucose derangements (hypo or hyperglycemia) and hyperbilirubinemia (elevated levels of bilirubin in the blood) and evaluate liver and kidney function.
  • Xrays and/or ultrasound of the thorax and abdomen to look for abscesses, kidney infection, pyometra, cancer, and free fluid.
  • Endotracheal wash and culture.
  • Blood bacterial culture.
  • Echocardiogram (ultrasound of the heart).
  • Coagulation profiles are a group of tests to measure the blood’s ability to clot.
  • A cerebrospinal fluid (CSF) tap is a test to look at the fluid that surrounds the brain and spinal cord.


The goal of treatment is to address the underlying disease and provide supportive care. Aggressive treatment is required for cats with sepsis. This will include:

  • Intravenous antibiotics to treat the infection. Broad-spectrum initially until culture and sensitivity are performed to determine the most effective antibiotic.
  • Fluid therapy to maintain hydration, correct electrolyte imbalances and increase blood pressure.
  • Vasopressors such as dopamine to increase blood pressure.
  • Nutritional support may include a temporary feeding tube for cats who are not vomiting. Total parenteral nutrition, which is intravenous administration of nutrients, bypassing the usual process of eating and digestion for cats who are vomiting.
  • Blood transfusion to treat anemia (whole blood) and coagulopathy (plasma).
  • Surgical removal of infected tissue, where indicated.
  • Thoracic drainage tubes to remove fluids from the pleural cavity in cats with pyothorax.
  • Analgesics to manage pain, where necessary.

During treatment, the veterinarian will closely monitor blood for electrolyte imbalances, clotting, red and white blood cell counts and organ function.


  • Julia Wilson, 'Cat World' Founder

    Julia Wilson is the founder of Cat-World, and has researched and written over 1,000 articles about cats. She is a cat expert with over 20 years of experience writing about a wide range of cat topics, with a special interest in cat health, welfare and preventative care. Julia lives in Sydney with her family, four cats and two dogs. Full author bio