Sepsis and Septic Shock in Cats: Symptoms, Causes, and Treatment

Without prompt and intensive treatment, sepsis can be life-threatening for cats. Lebedko Inna / Shutterstock.com

Sepsis happens when your cat’s immune system overreacts to an infection somewhere in their body. Instead of attacking the infection (what your cat’s immune system is designed to do), it begins to attack inside your cat’s body. This causes damage to multiple organs and tissues and can be fatal.

Importantly, sepsis is a rare complication of an infection. Most of the time your cat’s immune system will respond appropriately to fight off illness and infection. But because sepsis is so serious—and can come on very suddenly—it’s important to know how to recognize the signs quickly.

Sepsis Vs. Septic Shock

It’s easy to get confused by the terms sepsis and septic shock. Septic shock is the last stage of sepsis, where a cat’s blood pressure becomes very low and does not respond to treatment with intravenous fluids. As a result, the blood struggles to carry oxygen that the organs and tissues need to stay alive.

Septic shock is the most serious complication of sepsis, and unfortunately, many cats will not survive—even with intensive veterinary treatment.

Causes of Sepsis in Cats

Sepsis can be triggered by any type of infection—bacterial, fungal, or viral—anywhere in your cat’s body. Sometimes, the infection is easy to find, such as an infected bite or wound. Other times, it can be hard to identify. One study looking at the epidemiology of sepsis in cats found that the most common infection in cats with sepsis was caused by bacteria in the peritoneal space and urogenital system.

But confusingly, sepsis isn’t caused by the infection itself, but by an overreaction of your cat’s immune system to the infection. This is why sepsis is currently defined in people as the presence (or suspicion) of infection, alongside organ dysfunction.

Normally, when your cat’s immune system encounters an infection, it will release cells and chemicals to fight it off. When sepsis occurs, the immune system turns this attack not only on the infection but also on your cat’s own body. Sepsis comes on suddenly and can cause serious damage to the organs and tissues in your cat’s body very quickly if it is not treated.

Nobody knows exactly why the immune system reacts in such an exaggerated way in cases of sepsis. But, in people, we know that younger and older people, those with poor immune systems, and certain additional medical problems are most at risk.

Risk Factors for Developing Sepsis in Cats

Cats with sepsis can become unwell rapidly, but the early signs can be vague and tricky to spot. larisa Stefanjuk / Shutterstock.com

Only a few research papers have looked specifically at cats with sepsis. One study that investigated sepsis in cats was able to identify certain health conditions that put cats at greater risk:

• Diabetes mellitus
• Cancer
• Hyperthyroidism
• Hypertrophic cardiomyopathy
• Chronic kidney disease

Sepsis Symptoms in Cats

Although sepsis is very serious, it can be hard to spot. If your cat has an obvious infection (for instance an abscess or bite wound) and becomes unwell, this might make you and your veterinarian more suspicious.

But often the infection is hard to find, and the symptoms you might see at home are vague and nonspecific. They include:

• Lethargy
• Vomiting
• Diarrhea
• Abdominal pain
• Loss of appetite
• Breathing fast (tachypnea)
• Low heart rate (bradycardia) or high heart rate (tachycardia)
• Low or high temperature

Septic Shock Symptoms in Cats

If sepsis becomes severe, blood pressure can become dangerously low, and septic shock can occur. Septic shock can be rapidly fatal without intensive veterinary treatment. Symptoms include:

• Low blood pressure (hypotension) that doesn’t respond to intravenous fluid therapy
• Collapse
• Pale mucous membranes
• Weak pulse
• Low temperature (hypothermia) causing cold extremities
• Death

Diagnosis of Sepsis and Septic Shock in Cats

The symptoms in cats with early sepsis can be nonspecific, meaning it can be hard to diagnose. However, it is vital to identify sepsis as early as possible to give your cat the best chance of survival. So, your veterinarian will need to perform a variety of tests. These usually include basic blood tests, including a complete blood count and biochemistry.

Your veterinarian will be looking for certain changes in these blood tests to alert them to the possibility of sepsis, including:

• Anemia
• Low platelets
• Abnormal white blood cell numbers
• High glucose (hyperglycemia)
• Low albumin (hypoalbuminemia)
• High bilirubin (hyperbilirubinemia or jaundice)

Veterinarians use a set of clinical criteria to diagnose sepsis in cats and dogs called the systemic inflammatory response syndrome ^[2](SIRS) criteria. To diagnose a cat with sepsis, they must have (or be suspected to have) an infection, as well as three out of four of the SIRS criteria:

• Low or high temperature
• Low or high heart rate
• High respiratory rate
• Low or high white blood cell count on blood tests

If, after a full physical examination and blood tests, your vet is worried your cat might be suffering from sepsis, they will likely recommend more tests to assess the severity of the sepsis and look for the underlying infection. These might include:

• Clotting tests
• Blood gas analysis and lactate testing
• Urinalysis
• Imaging of the chest and abdomen with x-rays or ultrasound
• Culture of blood, urine, or feces

The results of these further tests will allow your veterinarian to understand the severity of your cat’s sepsis, and what infection might have triggered it. This will help them know exactly what treatment your cat needs.

Treatment for Cats With Sepsis and Septic Shock in Cats

Cats suffering from sepsis need intensive hospital treatment to survive. RJ22 / Shutterstock.com

Cats with sepsis need intensive hospital care to survive, especially if they are showing signs of septic shock. An article in Today’s Veterinary Practice journal on stabilizing and treating cats with systemic inflammatory response syndrome and sepsis identified three main goals when treating a cat with sepsis:

1. Rapid support of their circulation and blood pressure using intravenous therapy, and sometimes medication
2. Treatment of infection with appropriate antimicrobials
3. Supportive care

Recovery from sepsis is possible, but it depends on the cause of the underlying infection, how early aggressive treatment is given, and how the cat responds to it. Studies looking at mortality rates of cats with sepsis have found a survival rate of around 60%.

However, it’s important to understand that these studies are based on cats being treated in referral-level hospitals with specialized care. This level of care is intensive and requires significant financial input.

Cats that progress to septic shock have a worse prognosis, with 80% to 90% not surviving—even with intensive care.

Supporting the Circulation System

Cats with sepsis have poor blood pressure and circulation, which can cause damage to their tissues and organs. The first-line treatment is intravenous (IV) fluids through a drip. The aim is to improve blood pressure—and therefore the delivery of oxygen—around the body.

Cats suffering from severe sepsis might need intravenous transfusions of blood products or albumin, depending on the results of their blood tests.

Sometimes, IV fluids alone aren’t enough to improve blood pressure and circulation. This can signify a cat is suffering from septic shock. Your veterinarian might need to use certain medications alongside IV fluids to try and maintain your cat’s circulation and prevent serious organ damage.

Treating Infection With Antimicrobials

Although sepsis is caused by the body’s response to an infection, rather than the infection itself, it is still vital to treat the underlying infection. In fact, guidelines for treating sepsis in people state that using antimicrobials as early as possible is one of the only treatments that can significantly improve the chances of survival.

Before giving antimicrobials, your veterinarian will take samples for culture and sensitivity testing. The results of these tests will allow them to identify the exact type of infection, and the most effective antimicrobial treatment to use. However, these results can take several days to get back. In the meantime, cats with suspected sepsis should be started on broad-spectrum antibiotics as early as possible.

Recovery and Supportive Care of Cats With Sepsis

While in the hospital, your veterinary team will also give your cat supportive care to manage their symptoms. This will help your cat feel better, start eating and drinking earlier, and manage any pain they might have—all important factors in getting them home as soon as possible.

The type of supportive treatment your cat will need will depend on their symptoms, but it might include:

• Anti-sickness medication
• Antacids
• Pain relief
• Appetite stimulants

It’s also important that once they’re stable, cats receive nutrition as early as possible. If your cat won’t eat by themselves, your veterinarian may discuss placing a feeding tube.

Comforting Cats With Sepsis

Spending time grooming your cat in hospital can help them to feel safe and relaxed. RONEDYA / Shutterstock.com

While sepsis isn’t a condition that can be managed at home, you can still play an important role in your cat’s recovery while they are in the hospital. This could include:

• Bring in familiar things from home: Familiar scents help cats feel relaxed and safe in the hospital. So (if your hospital allows it), consider bringing bedding, toys, or even an item of your clothing.
• Let the nursing team know their likes and dislikes: Every cat is unique, so nursing them is unique, too. It can help to let your cat’s nurses know what they do and don’t like. This can be anything from where they like to be petted (and where they don’t!) to their favorite type of food.
• Provide their favorite food: Tempting cats to eat in the hospital is often challenging. It can help to bring in some of their usual or favorite foods, especially if they are usually a fussy eater.
• Visit them in the hospital: Once your cat is stable, most veterinary hospitals will allow you to visit. Spending time grooming, petting, and encouraging them to eat can help them feel relaxed and speed up their recovery.

Once your cat is ready to go home, your veterinary team will let you know exactly how to care for them. They will need a quiet, comfortable place to recover. It can help to write a chart of when they are due certain care or medication.

How To Prevent Sepsis in Cats

We don’t fully understand what causes the exaggerated immune response that leads to sepsis. But we do know that this response is triggered by an infection. So, the main ways to prevent sepsis in your cat are to reduce their risk of getting an infection and identify and treat it early if they do. You can do this by:

• Ensuring your cat receives all their recommended vaccinations and preventative health care
• Grooming your cat daily to check for wounds that could become infected
• Taking them to a vet as soon as possible if you suspect they have an infection or they are otherwise unwell
• Using antimicrobials as prescribed and ensuring you finish the full course