Under the current definition, sepsis involves organ dysfunction caused by the body's unbalanced defence response to infection. Demonstrating microbes in the blood or simultaneous damage to several organs is not required for diagnosis. The infection itself may remain localised while the response it triggers affects other parts of the body.
When to see a vet urgently
Seek emergency care immediately if an ill, injured or recently operated cat develops the following signs:
- Collapse, inability to stand or unusually poor responses.
- Difficulty breathing, or pale or bluish mucous membranes.
- Severe lethargy and coldness, or rapidly worsening health.
- Signs of infection accompanied by severe weakness, refusal to eat or confusion.
Do not wait for every sign to appear. You can find a vet near you.
Overview
Sepsis develops when bacteria, viruses or fungi enter the bloodstream from a local site, such as a wound, abscess, urinary tract or lungs. The body responds with intense inflammation that damages its own tissues and organs. Without intensive care, sepsis rapidly leads to shock and death.
Spread through the bloodstream describes one possible sequence, but sepsis does not simply mean a blood infection. The inflammatory response can alter blood vessel function and reduce blood flow to tissues. As a result, the kidneys or respiratory system, for example, may not function normally. Septic shock is a particularly severe form of sepsis, and not every case follows the same course or progresses at the same speed.
Causes
- Infected wounds and abscesses.
- Peritonitis, for example from a ruptured bowel or uterine infection (pyometra).
- Severe urinary tract infections.
- Pneumonia and inflammation of the pleura.
- Complications after surgery.
- Viral infections that weaken immunity, such as FeLV and FIV.
- Systemic fungal infections.
The list includes both possible infection sites and diseases that weaken immunity. FeLV or FIV infection alone does not mean sepsis. Nor does every wound, abscess or postoperative infection cause it. Diagnosis requires infection and associated organ dysfunction.
An intense inflammatory response can also occur without infection, for example after tissue damage. Fever, rapid breathing or an abnormal blood count alone do not define this as sepsis. Your vet investigates the possibility of infection and other causes of poor general health at the same time.
Risk factors
- Kittens and older cats.
- Cats with reduced immunity, for example from viral infections or wasting.
- Cats after serious injuries or surgery.
- Cats living in unhygienic conditions.
There is less research on risk factors and the predictive value of individual findings in cats than in dogs. The list is not a rule for excluding sepsis: a previously healthy adult cat can also develop a severe infection. Age, underlying diseases, medicines and the infection site are considered in the overall assessment.
Typical symptoms
- High or abnormally low body temperature.
- Dullness, apathy and loss of appetite.
- Increased breathing and heart rates.
- Pale or bluish mucous membranes.
- Weakness and an unsteady gait.
- Signs of internal organ damage, including vomiting, diarrhoea, jaundice and seizures.
- In the final stages, collapse and loss of consciousness.
In cats, severe circulatory compromise can also involve a slow heart rate and low temperature. The absence of fever or an increased heart rate is therefore not reassuring. Severe tiredness at home may mean that your cat cannot get up or respond normally to handling. Judging temperature by touch alone neither confirms nor rules out sepsis.
Symptoms also depend on the original disease. A urinary tract infection involving the kidneys may occur without fever or abdominal pain. Suspicion is therefore not assessed using one supposedly characteristic symptom. A marked decline in general health after surgery or a wound needs reassessment, even if the skin looks only mildly changed.
Complications and consequences
- Septic shock.
- Multiple organ damage affecting the liver, kidneys, heart and lungs.
- Disseminated intravascular coagulation (DIC), a clotting disorder involving both bleeding and blood clots.
- Death despite treatment.
In septic shock, blood flow to tissues is impaired and circulation remains unstable despite appropriate fluid treatment. Fever alone does not indicate shock. In hospital, monitoring includes blood pressure, level of consciousness and organ function to detect deterioration promptly.
With a clotting disorder, small blood clots can form while platelets and clotting factors are consumed. The risk of bleeding also increases later. Not every cat with sepsis develops DIC, and its early stages do not always cause visible bleeding. Assessment requires blood tests and monitoring of changes in the results.
Diagnosis at the vet
- A complete blood count, looking for increased or decreased white blood cells, anaemia and low platelet numbers.
- Blood biochemistry to assess liver and kidney function.
- Cultures of blood and the infection site.
- Ultrasound and X-rays to look for the source of infection.
- Urinalysis if sepsis originating in the urinary tract is suspected.
Repeated assessment
The initial examination assesses breathing, circulation, temperature, pain and alertness. Stabilising treatment may begin while investigations continue. Report recent injuries, procedures, medicines and how quickly your cat's condition changed. Previous test results and culture findings may help locate the infection.
Blood tests assess not only inflammation but also blood glucose, electrolyte balance and organ function, for example. Changes in blood pressure, urine production and lactate add to the assessment. Lactate relates to tissue metabolism among other things, but a single value does not confirm sepsis. General inflammatory response criteria alone are also insufficient for diagnosis.
Finding the source of infection
Samples are chosen according to the suspected source. Urine culture can help investigate a urinary infection; abdominal fluid may be examined in peritonitis. Imaging looks for a leaking organ, accumulated fluid or another focus needing treatment. Not every cat undergoes the same set of investigations.
Culture and susceptibility testing help identify the microbe and choose an effective medicine. Blood culture is a useful additional investigation, but a positive result is not required for a sepsis diagnosis. The need for treatment is assessed as a whole, and a seriously ill cat's treatment is not left waiting solely for final culture results.
Hospital treatment
Treatment supports vital functions and addresses the infectious agent and its source. Your cat may need oxygen, intravenous fluids, pain relief and controlled warming. Fluids are adjusted to circulation and treatment response, because excessive fluid can also cause harm. If blood pressure and tissue blood flow remain inadequate, medicines to support circulation may be needed.
Treating the infection and its source
When a serious bacterial infection is suspected, antibiotics are started before final culture results. The choice is refined according to results and your cat's condition. For example, in septic peritonitis, antimicrobial treatment starts when the disease is suspected or confirmed. Viral or fungal infections need treatment appropriate to the agent and situation; antibiotics do not work against every microbe.
Medicines alone are not always enough if the source sustaining the infection remains. A leaking section of bowel may require urgent surgical repair. With pyometra, the usual treatment is removal of the infected uterus and ovaries after essential stabilisation. The timing of the procedure and circulatory support are coordinated.
Nutrition and other supportive care
Causes of not eating, such as pain, nausea and fluid imbalance, are treated. A nutritional plan is made early, with a feeding tube used if necessary. Circulatory stability and significant fluid and electrolyte disturbances are considered before feeding begins. A weak cat must not be force-fed or given water by syringe.
Recovery and prognosis
Prognosis depends on the severity of organ dysfunction, control of infection and response to treatment. Research in cats is limited, so mortality figures for dogs or people cannot be directly applied to an individual cat. Repeated assessments show the direction of change better than one value measured at presentation.
At discharge, you will receive instructions on medicines, feeding, any wound and follow-up checks. Monitor appetite, breathing, urination and alertness. Report new severe lethargy or deterioration immediately. Increasing swelling, a bad smell or discharge from a surgical wound require contact with the practice. Do not apply cleaning agents or creams to a wound without specific instructions. Do not start leftover antibiotics or human painkillers.
Prevention
- Treat all infections and inflammation promptly.
- Ensure wounds and abscesses are cleaned and drained properly.
- Surgery and other procedures should use sterile technique.
- Vaccinate your cat against viral diseases, including feline panleukopenia and, for at-risk cats, FeLV.
- Treat chronic diseases that weaken immunity.
Follow wound and surgical incision care instructions, but do not try to resolve a decline in general health through cleaning alone. Do not use alcohol or hydrogen peroxide on a surgical wound. Vaccines protect against specific pathogens; they do not prevent every infection that can lead to sepsis. Vaccination planning is based on your cat's health and infection risk.
Important for cat owners
Sepsis is one of the most dangerous complications of infection. Remember that if your cat suddenly deteriorates after an injury, infection or surgery, with fever, lethargy and refusal to eat, you should go to a veterinary practice or emergency vet immediately. Early diagnosis and intensive care are the only chance of saving your cat.
Seek assessment even without fever. A low temperature, unusual weakness or difficulty breathing can indicate a serious situation.
This article provides general information and does not replace veterinary care. Contact a vet if you notice signs of illness in your cat.
Frequently asked questions
Is sepsis the same as bacteria in the blood?
No. In sepsis, a dysregulated defence response to infection causes organ dysfunction. Demonstrating microbes in blood can help investigations, but a positive blood culture is not essential for diagnosis.
Can a cat have sepsis without fever?
Yes. A seriously ill cat may have a low temperature, and circulatory compromise can also involve a slow heart rate. Seek assessment based on general condition without waiting for fever.
Why might sepsis require surgery?
The source sustaining the infection may need removal or repair. A leaking bowel or infected uterus, for example, may not recover with medicines alone, even while vital functions are supported.
Can sepsis be treated at home with an antibiotic?
Suspected sepsis requires urgent veterinary assessment. An antibiotic alone does not correct circulatory or organ dysfunction or remove every infection source. Do not wait for a medicine started at home to take effect.
This article is for general information only and is not a guide to treatment. If you notice the first signs of illness, contact your vet.
Paw4care editorial team
Sources
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