17 Causes of Sudden Death in Cats

The sudden loss of a beloved pet is a distressing event that many owners have experienced. There are many sad stories of cats dying, seemingly for no reason. Other owners tell of cats succumbing to an illness in a matter of hours. Understanding the causes of sudden death in cats can prevent the loss of life from occurring in the future.

What may seem like sudden death in cats is often the result of an ongoing illness in its final stages. Cats die suddenly due to medical conditions such as sepsis, shock, kidney failure, poisoning, urinary obstructions, strokes, heart failure, choking, envenomation, heartworm disease, hypoglycemia, and hereditary conditions.

Minimizing your cat’s exposure to the various causes of sudden death in cats begins with regular veterinary check-ins and vaccinations against disease. You may wish to keep your cat exclusively indoors or create an enclosed outdoor space to protect your cat from outside dangers, such as traffic and wild animals.

Why Do Cats Die Suddenly?

Let’s explore the different reasons why cats die:

1/ Hypertrophic Cardiomyopathy

The Journal of Veterinary Cardiology stated that cardiomyopathy is the most common form of heart disease in cats.

Cardiomyopathy is hereditary and not due to improper diet or exercise. This condition results in the heart muscles not developing properly and thickening, leading to compromised cardiac function.

Cardiomyopathy is neither preventable nor curable, but it can be diagnosed and treated. Unfortunately, the first symptom is often sudden death. So, a cat may cry out in pain or surprise before dying a moment later.

Other symptoms include breathing difficulties, exercise intolerance, and heart murmurs. These can appear shortly before the heart gives out or when the cardiomyopathy is non-fatally triggered by high blood pressure.

A vet may detect murmurs earlier during a check-up. Treatment for managing the symptoms of cardiomyopathy usually involves beta-blockers to limit stress and high blood pressure.

2/ Poisoning

The Journal of Vet Cardiology studied 252 cats that died unexpectedly within 2 months.

Poisoning was among the most common reason for necropsy after an unexpected death. 158 of the 252 cats died at a veterinary clinic due to suspected poisoning. Poisoning can occur through ingestion, inhalation, and skin contact.

Many foods and plants are toxic to cats. Garlic, onions, and chocolate are common in our diets but can induce toxicosis in cats. These toxins can even be absorbed through the skin via sprays, oils, or aerosolized particles. A cat may even lick the particles off its fur, leading to toxicosis.

Airborne poisonings are restricted to an over-exposure to carbon monoxide. Usually, this only occurs in poorly ventilated spaces, such as a garage with a running car. Smoke from a fire can also cause a cat to suffocate. This could be an out-of-control house fire or a fire in a fireplace with a blocked chimney.

Preventing poisoning in cats centers around ensuring that it’s fed the right foods and cannot access harmful chemicals or dangerous human foods. Keeping your cat out of the garage is also recommended.

Poisoning in cats isn’t always accidental, as people intentionally poison cats. This, alongside other reasons, is why vets increasingly recommend keeping cats indoors or creating an enclosed outdoor enclosure that keeps them safe.

3/ Feline Asthma

Feline asthma is an inflammatory respiratory disease that can vary in severity.

One cat may only experience minor coughs when the asthma is triggered. In contrast, another cat may endure severe constriction of the airways and respiratory distress that’s severe enough to result in death.

Depending on the severity of asthma, the symptoms include:

• Shallow breathing
• Coughing or hacking breaths
• Inability to exercise
• Wheezing
• Strained or labored breathing

Feline asthma cannot be cured or prevented, but its symptoms can be managed with medication.

4/ Urinary Obstruction

Urinary obstructions are more common in male than female cats and can cause death within days.

Urinary obstruction is when a plug forms in the urethra and inhibits the passing of urine. This plug could be due to mucous, crystals, or bladder stones.

Signs of urinary obstruction include:

• Straining or unable to urinate
• Frequent trips to the litter box
• Crying or loud meowing while trying to urinate
• Urinating outside of the litter box
• Passing only small amounts of urine
• Blood in the urine

Urinary obstruction is often a secondary issue caused by another illness, such as an infection or tumor.

Prevention largely comes down to diet, sufficient hydration, enrichment, and entertainment. A vet will recommend foods specifically for urinary care if your cat is predisposed to urinary crystals.

5/ Trauma

Sudden death by trauma is a common occurrence in outdoor cats.

One study, published in The Canadian Veterinary Journal, found that half of all cats that died unexpectedly did so due to trauma. This trauma was primarily caused by motor vehicles.

Average lifespans reflect this statistic. On average, outdoor cats live for just 2-5 years, whereas indoor cats live for 17-20 years.

Outdoor cats are also exposed to:

• Predatorial animals
• Diseases
• Weather events
• Parasites
• Toxic plants and chemicals
• Animal cruelty
• Machinery

That said, homes are full of hazards, such as high shelves and reclining chairs.

Even though a cat may be particularly good at landing on its feet, a bad fall can still lead to injury. This may even be severe enough to cause sudden death, especially if the trauma is to the head or neck.

6/ Blood Clot

A blood clot, or thrombus, can cause sudden death in cats depending on where the clot forms. A clot forms when the blood flow in an artery or vein is interrupted or blocked or when a blood vessel’s lining is damaged.

When a part of this clot breaks off, it is called an embolus, and this traveling clot can become lodged elsewhere in the body. Blood clots can cause cats to die suddenly if the clot occurs in the lungs, heart, or brain.

Signs of a blood clot include coughing up blood or bloody mucus, difficulty breathing, partial or full paralysis, weakness, or bloody urine.

7/ Sepsis

Sepsis is described in Veterinary Clinics: Small Animal Practice as one of the most challenging illnesses to treat. It’s a full-body infection that, even with aggressive treatment, has a 20%-68% mortality rate.

The situation is urgent by the time the infection has moved to the blood and induced sepsis (blood poisoning). Death can occur shortly after sepsis has caused septic shock.

Sepsis can be caused by bacterial infections, ruptured intestines, kidney infections, peritonitis, pneumonia, and dental disease.

The initial signs of sepsis include disorientation, refusal to eat, shaking, fever, rapid heartbeat, rapid breathing or panting, and decreased urinary output.

Treatment involves supportive therapies and medications. The chances of survival lessen if the sepsis has become septic shock.

8/ Heart Failure

A cat’s instinct is to hide pain or illness, so heart failure has often progressed to a life-threatening state by the time the symptoms become apparent.

At this stage, death can occur suddenly. Heart failure is caused by several other illnesses, including hypertrophic cardiomyopathy.

Heart failure occurs when the heart loses its ability to adequately distribute blood throughout the body. Recognizing heart failure is key in treating it at an early stage.

The symptoms include:

• Appetite loss
• Grey or purple gums
• Labored breathing
• Panting
• Coughing
• Weakness
• Lethargy

Pulmonary edemas are commonly caused by heart failure. This is a build-up of fluid in the lungs, and it’s often a sign that the cat is near-death.

The additional strain on the cat’s respiratory system and heart may cause its heart to cease functioning. Alternatively, the fluid in the lungs can cause the cat to drown.

9/ Shock

Shock occurs when the brain is deprived of oxygen, slowing down the circulatory system. It can rapidly worsen and cause death if left untreated.

Shock can be broken down into the following categories:

• Distributive shock, which is usually caused by infections and draws blood away from the central circulatory system.
• Hypovolemic shock, which is due to a large loss of blood or fluid.
• Cardiogenic shock, which is the result of heart failure.

There are various health ailments, infections, and traumas that can cause shock.

Trauma is the most common cause, as the body loses blood and fluids. Otherwise, the shock itself is a sign that an ailment has progressed to the point that it has become life-threatening.

Signs of shock include:

• Pale or discolored gums
• Depression
• Convulsions
• Disorientation
• Lethargy and weakness
• Hypothermia
• Rapid or shallow breathing
• Rapid or weak pulse
• Loss of consciousness

Depending on the cause of shock, it is usually treatable. Treatments vary based on the cause and type of shock.

10/ Strokes

A stroke is a cerebrovascular accident due to a disturbance of the blood supply to the brain.

What causes this disturbance could be anything from high blood pressure, tumor, cancer, poison, or disease. A stroke leads to the paralysis of one side of the body.

Additional signs of strokes in cats include:

• Disorientation
• Incoordination and falling over
• Head pressing
• Stumbling or abnormal gait
• Weakness
• Partial paralysis on one side of the body
• Lethargy
• Seizure
• Unequal pupil sizes

11/ Choking

Choking occurs when the cat swallows an item, which becomes lodged in the larynx or trachea. This could be food, organic material (like plants), or small objects (like bottle caps, pen lids, or broken toy pieces).

Choking can happen with food-motivated kittens. This usually occurs when the kitten eats dry or wet food served in larger chunks. A food-motivated kitten may be so eager to eat that it won’t pause to break food into smaller pieces.

Choking can lead to unconsciousness in minutes and death if the blockage isn’t removed.

Signs that your cat is choking are:

• Coughing or gagging
• Panicked behavior
• Pawing at the mouth
• Drooling
• Assuming a hunched position with its neck stretched out
• Labored or wheezing/rasping breathing
• Fainting

If your cat is choking, keep it calm, put it in a carrier, and take it to the vet. If your cat has fainted or is struggling to breathe, inspect its mouth. If you can see an obvious blockage, try to remove it.

If your cat has swallowed string, or something similar, don’t pull it out. You could cause internal damage if the string has gotten caught in the throat or stomach. Take your cat to the vet to have it removed.

12/ Venomous Animals

One of the perils of allowing a cat outdoors is its exposure to other animals—namely, venomous animals like snakes, lizards, and spiders.

Although venom lethality varies between species, a venomous bite of any kind can be a fatal wound for a cat. Depending on the toxicity of the venom, death could even occur in a matter of hours.

Symptoms of envenomation include:

• Weakness
• Collapse
• A bite site (swollen and discolored)
• Vomiting
• Shaking or twitching (full body or muscular)
• Dilated pupils
• Bloody urine
• Partial or complete analysis

If a snake or spider has bitten your cat, immobilize it and keep it calm.

Vet clinics often have access to anti-venoms and anti-venins. Describing the animal that bit your cat will assist your vet.

13/ Hypoglycemia

Hypoglycemia (low blood sugar) can result in death in severe cases.

It’s caused when the cat’s body is deprived of the natural sugars it converts into energy. This could be due to improper diet, starvation, intestinal parasites, or other health issues that impact blood sugar levels.

Hypoglycemia has the following symptoms:

• Lethargy
• Muscular twitches
• Trembling
• Loss of appetite
• Blindness
• Lack of coordination
• Unconsciousness

Diagnosing hypoglycemia requires veterinary tests.

14/ Heartworm Disease

Heartworm disease can strike suddenly, and the damage has already been done to the heart by the time symptoms present themselves. A cat may not present symptoms until it suddenly dies from heart failure induced by this parasite.

Heartworm disease is caused by the parasite Dirofilaria immitis, which is transmitted via mosquitoes. When a mosquito bites an infected animal, it ingests larval heartworms. At this stage in the life cycle, heartworms live in the bloodstream.

When an infected mosquito bites a cat, it can infect it with larval heartworms. Once a larva has matured, which takes 3-4 months, it travels to the heart. It only takes 2-3 adult heartworms living in the heart (or lungs) for a cat to perish. Juvenile heartworms also live in the pulmonary arteries in the lungs, where issues can arise.

The signs that a cat has heartworm include the following:

• Coughing and coughing up blood
• Vomiting
• Anorexia
• Weight loss
• Difficulty breathing
• Rapid breathing
• Decreased ability to exercise
• Blindness
• Seizures
• Incoordination
• Circling

Preventing heartworm disease involves ensuring that your cat takes its heartworm medications. Limiting your cat’s exposure to the outdoors lowers its chances of being infected.

15/ Diabetic Ketoacidosis

Diabetic ketoacidosis is a condition that arises when diabetes goes untreated.

Essentially, the condition has progressed to the point where the body lacks insulin, so sugar can’t reach the cells, resulting in cell starvation.

A body going into cell starvation will try to break down fat as an alternate energy source. An unfortunate by-product of this process is the production of ketones, which don’t produce energy cleanly.

A body relying on ketones for energy will experience pH and electrolyte imbalances, and this causes dehydration, leading to further metabolic imbalances.

Signs of diabetic ketoacidosis include:

• Weakness
• Vomiting
• Excessive thirst
• Excessive urination
• Weight loss
• Flaky skin
• Odd smelling breath
• Diarrhea
• Loss of appetite or anorexia
• Lethargy
• Abnormal breathing pattern
• Jaundice
• Abdominal pain

In severe cases, the cat will fall into a comatose state. As the Journal of Veterinary Internal Medicine notes, remission from diabetic ketoacidosis is possible following treatment.

Treatment for diabetic ketoacidosis involves several days of medications and fluids to balance out metabolic disarray caused by the ketones. Following recovery, the cat will remain on medication for life, and its blood sugar levels will need to be closely monitored.

16/ Lily Nephrotoxicity

All parts of the lily plant are toxic to cats, from the flower’s petals to the roots of the plant. Even drinking from the water dish of a lily plant can be fatal.

Lilies cause acute kidney failure within 3 days of ingestion. Without treatment, a cat will die.

Signs of lily ingestion include:

• Drooling
• Vomiting pieces of the plant
• Loss of appetite
• A sudden increase in urination, followed 1-2 days later by no urination
• Dehydration

Ensure that any houseplants in your home are non-toxic to cats. Of course, preventing exposure to these dangers is more difficult if the cat is allowed outside.

17/ Acute Kidney Failure

Acute kidney failure results in a sudden decline in kidney function.

This leads to a build-up of toxins and fluids in the body, eventually leading to death. Even with treatment, there’s a high mortality rate.

The kidneys process waste, regulate fluid composition in the body, and stimulate red blood cell production. When the kidneys aren’t working properly, neither does the rest of the body.

Acute kidney failure leads to the following symptoms:

• Disorientation
• Lethargy
• Weakness
• Altered drinking volume and urination
• Incoordination
• Strained urination
• Loss of appetite
• Vomiting
• Decreased urine production.

Many things can cause acute kidney failure, including poison (such as antifreeze and lilies), low blood and oxygen flow to the kidneys, a ruptured bladder, bacterial infections, and obstruction in the kidneys.

Suddenly losing a cat is a traumatic event. We love our cats, and death is never easy to deal with. Of course, sudden death can seem particularly unfair.

Many owners may wonder if they could have done anything to prevent their cats from dying. There are sometimes ways to prevent some of the causes of sudden death, but not all of them.

All that you can do is increase your awareness of conditions that are most likely to end your cat’s life prematurely.