Septic Shock in Cats

Cats with impaired immune systems, very young or old cats, or cats with an underlying condition or disease are more susceptible to bacterial infection, sepsis, and progression to septic shock. Septic shock is an emergency requiring urgent veterinary care to prevent fatality. 

Shock due to bacterial infection (septic shock) in cats is a life-threatening complication of systemic bacterial infection (sepsis). Sepsis or septicemia is illness resulting from a bacterial infection that has moved into the animal's bloodstream, spreading the bacterial infection throughout the cat’s body. Once sepsis has occurred it can progress to septic shock rapidly as the immune system responds to the bacterial presence, producing substances to combat the infection, and the bacteria itself produces toxins. Theses substances and toxins cause blood vessels to dilate, resulting in lowered blood pressure and reduced blood flow to vital organs such as the kidneys and brain. The heart increases output to compensate but eventually weakens, lowering blood flow and oxygenation even further. In addition, the heart itself can be compromised by the bacterial infection. The result is organ malfunction and eventually damage due to lack of oxygen to the tissues. If blood vessels are also compromised and begin leaking, fluid builds up in tissues, causing edema. In the lungs, this results in respiratory distress. 

Initial signs of septic shock include:

• Disorientation
• Shaking
• Fever
• Rapid pulse
• Rapid breathing/panting
• Decrease in urinary output

Symptoms of later stages of septic shock (characterized by organ and organ system failure) include:

• Rapid or slow heart rate
• Pale gums
• Cold extremities
• Low body temperature
• Capillary hemorrhaging - small pinpoint red dots on tissues
• Severe weakness
• Lactic acid buildup in blood due to poor oxygenization contributes to organ malfunction from acidic blood
• Kidney failure - kidneys decrease or cease production of urine
• Respiratory distress as lungs fail
• Heart failure resulting in edema and swelling
• Blood clot disorder
• Bleeding in the gastrointestinal tract

Septic shock is a complication of sepsis, which occurs when localized bacterial infection has moved into the bloodstream (blood poisoning). Some animals seem to have a genetic predisposition to bacterial infection and immune system dysfunction. Genetic predisposition, organ dysfunction, or presence of illness or other medical conditions greatly complicate the progression of bacterial infection to sepsis and septic shock.

Conditions predisposing or causing infection in your cat include:

• Postoperative infection from surgery
• Septic pancreatitis
• Conditions that decrease immune system functioning such as diabetes, Cushing's disease, chemotherapy treatment, high dose steroid treatment
• Gastrointestinal disorder or disease- compromised GI tract lining or peritonitis
• Urinary tract infection - common in male cats
• Bacterial infection of heart lining
• Pneumonia
• Meningitis
• Abscess in liver
• Abscess from bite wounds.
• Traumatic injury

Viral infections such as feline leukemia virus greatly complicate bacterial infection. Also, the type of bacteria and location of infection complicates the risk of sepsis and septic shock.

Diagnosis of septic shock is not always straightforward, as bacteria in the blood are not always easily detectable and cultures of tissues and fluids to determine the presence of bacteria take time to develop. Due to the urgency of septic shock your veterinarian may start treatment prior to a confirmed diagnosis of septic shock. 

Your veterinarian will perform a complete physical assessment and take a medical history of your cat, paying special attention to any conditions that would cause bacterial infection or that would predispose your cat to infection, such as immune system compromise.

Your veterinarian will perform a variety of tests to discover any underlying conditions that might cause bacterial infection. Blood count and blood chemistry tests, urinalysis, x-rays, echocardiograms, and ultrasounds will be useful in identifying an underlying cause.

Sepsis diagnosis can be determined by looking for indications in blood samples of abnormal levels of white blood cells, decreased oxygen levels, decreased platelets, increased lactic acid, and increased metabolic waste products in blood samples. In addition, fluid samples from tissues can be taken and cultures performed to determine the presence and type of bacteria. This information can be used to customize treatment specific to the type of bacteria present.

Treatment of septic shock is urgent as this is a life threatening condition. Hospitalization will be required and supportive therapy for treatment of shock will begin immediately. Intravenous therapy will be administered to increase blood pressure and medication to ensure adequate blood flow to vital organs will be administered. Oxygen will also be administered to your cat to increase oxygenation to tissues and organs. Antibiotic therapy will be started immediately. The type of antibiotic will be tailored to the type of bacterial infection and location, if possible. If this information is not available antibiotics treatment will be initiated and when test results are available the antibiotic treatment customized if necessary to the bacterial infection identified. Vasopressor drugs to constrict dilated blood vessels and improve blood pressure may be administered. Surgery to drain an abscess or remove dead, infected tissue may be required. Blood transfusion will be administered as needed. Septic shock is an urgent life-threatening condition and prognosis is guarded in spite of treatment fatality is a real possibility.

Prognosis and recovery of septic shock depends on the successful treatment of the underlying cause. Extensive follow-up intravenous therapy and specialized diet to ensure return to correct blood chemistry will be needed. Additional treatment for respiratory, heart, and organ damage that may have occurred may be required. Tests to check blood chemistry and urine and organ functioning will be performed until system functioning returns to normal. Depending on the procedures required during treatment, pain management may also be necessary.