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8 Cat Diseases That Cause Death: Our Vet Explains the Signs & Prevention

Written by: Dr. Samantha Devine DVM (Veterinarian)

Last Updated on April 18, 2024 by Catster Editorial Team

Female vet holding a sick cat close-up

8 Cat Diseases That Cause Death: Our Vet Explains the Signs & Prevention


Dr. Samantha Devine Photo


Dr. Samantha Devine

Veterinarian, DVM

The information is current and up-to-date in accordance with the latest veterinarian research.

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With an estimated 26% of homes in the United States owning cats1, it’s easy to see the impact these (usually) fuzzy felines have on our hearts. We want to do everything possible to keep them healthy and with us for as long as possible, so what diseases do you need to worry about for your cat? Is there anything you can do to prevent them?

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The 8 Cat Diseases That Cause Death

1. Heart Disease

Heart disease is tricky to diagnose in cats and is often underdiagnosed in general practice. An estimated 15% of cats have heart disease2, but unlike dogs, cats don’t always show changes on physical exams like a heart murmur.

Hypertrophic cardiomyopathy is the leading cause of heart disease in cats. The heart muscle thickens, so the muscle can’t work as effectively. This condition can cause sudden death in cats.

Cat sitting on a vet metal table
Image Credit: Tyler Olson, Shutterstock

Diagnosing Heart Disease in Cats

A physical exam is always helpful, but some cats don’t have a heart murmur, abnormal heart rhythms, pulse deficits, or other changes on the exam. If your veterinarian detects any of these changes, they’ll likely recommend further evaluation, with tests such as:

  • An electrocardiogram (ECG or EKG)
  • An echocardiogram (ultrasound of the heart)
  • Chest radiographs (X-rays)

A simple test many veterinarians utilize now is the NT pro-BNP. It’s a blood test that can help detect heart disease, and your veterinarian may suggest it before anesthesia, even in otherwise healthy cats.

Preventing Heart Disease in Cats

Unfortunately, genetics are responsible for many cases of heart disease. If you’re purchasing a cat from a breeder, especially if they’re a higher-risk breed like a Ragdoll or Maine Coon, check to see if a cardiologist has evaluated the parents.

Your cat is also at risk for heart disease if they do not eat a balanced diet. Historically, some cat foods were deficient in taurine, which led to heart disease. You should ensure your cat’s food meets AAFCO feeding guidelines in the United States.

2. Chronic Kidney Failure

Chronic kidney disease is prevalent in older cats. The rate of kidney failure, or renal failure, can be more than 30% of the population3, depending on the age group of the cat. With chronic kidney disease, your cat’s kidneys gradually lose their ability to concentrate urine and filter wastes.

Some signs of kidney failure include:
  • Excessive drinking (polydipsia)
  • Increased urination (polyuria)
  • Lethargy
  • Weight loss
  • Poor or unkempt hair coat

Kidney disease is linked to other conditions, including hypertension and anemia. The kidneys produce a hormone that stimulates red blood cell production. Low red blood cell counts, or anemia, are characterized by pale gums, weakness, elevated heart rate (tachycardia), and elevated respiratory rate (tachypnea).

Diagnosing Renal Failure in Cats

Your veterinarian will typically utilize blood work and a urinalysis to assess your cat’s kidneys. Two main values were traditionally associated with renal function: blood urea nitrogen (BUN) and creatinine (sometimes abbreviated CREA). These values increase when the kidneys aren’t functioning normally.

As much as 75% of the kidneys must be impaired to see a measurable change in the BUN and creatinine. A newer test on a value called SDMA can detect changes much earlier and is rapidly becoming the standard of care.

Your veterinarian will likely look at a urine sample to check your cat’s ability to concentrate their urine. It also allows the vet to check for evidence of infection, urinary crystals, and abnormal cells.

Other helpful tests for a cat with possible kidney disease include:

  • Ultrasound to image the kidneys
  • Blood pressure to make sure your cat isn’t hypertensive
  • A thyroid panel to evaluate your cat’s thyroid function, a condition that can mask or exacerbate kidney disease

Preventing Renal Failure in Cats

There’s no way to prevent kidney failure in cats completely. Regular exams and blood work can help your veterinarian detect changes sooner than waiting for signs to appear. A well-balanced diet is essential to stave off and manage kidney disease. Senior cat foods are typically protein and phosphorus-restricted. Prescription kidney diets are strongly recommended for most kidney-failure cats.

Make sure your cat drinks plenty of water. You can increase their water consumption by offering canned foods.

3. Feline Panleukopenia

Feline panleukopenia is a common virus affecting cats. It is species-specific, so it only affects cats, and it is sometimes referred to as feline distemper or feline parvovirus.

Feline panleukopenia can affect any cat, but the ones who are usually most severely affected are kittens and immunocompromised cats4. It can be deadly, and sometimes affected cats are found suddenly deceased, with little to no warning.

Signs of feline panleukopenia include:
  • Depression
  • Gastrointestinal signs such as vomiting and diarrhea
  • Fever
  • Inappetance

The name for the illness comes from the virus attacking rapidly dividing cells. It often affects white blood cells, decreasing their numbers and causing leukopenia.

tired or sick cat
Image Credit: Kginger, Shutterstock

Diagnosing Feline Panleukopenia

Your veterinarian may make a presumptive diagnosis based on your cat’s history and clinical signs to start supportive care. A lack of vaccines and possible exposure to other cats suggest a high risk of feline panleukopenia.

Your vet will likely suggest blood work to assess your cat’s white blood cell count and to check for other secondary issues, such as dehydration. Your veterinarian may also suggest diagnostic tests to confirm the illness, such as viral PCR tests submitted to a lab.

Preventing Feline Panleukopenia

The best way to prevent feline panleukopenia is by vaccinating your cat. Your veterinarian can help you determine an appropriate vaccination schedule for your cat.

You should also keep your cat away from potentially infected cats. Keeping your cat indoors is usually the safest course of action for your cat’s and others’ safety. When you adopt, purchase, or rescue a new cat, they should be quarantined from your other cats until their health is confirmed. Regularly wash and disinfect all dishes, toys, bedding, and litter boxes.

4. Hyperthyroidism

Hyperthyroidism is another common disease that can affect cats. It can lead to cardiovascular complications, kidney disease, blindness, and even death. Roughly 10% of cats older than ten years have hyperthyroidism5, making it the most common endocrine disease affecting our feline friends.

Cats with hyperthyroidism tend to lose weight quickly and have a ravenous appetite. They might show signs of rapid onset of blindness, with fixed, dilated pupils or walking into things, generally secondary to elevated blood pressure.

While this disease caused by an overactive thyroid gland can have detrimental effects, it has a good prognosis when treated. There are pills, as well as other treatments, such as radioactive iodine.

Diagnosing Hyperthyroidism in Cats

Your veterinarian may suggest a thyroid profile blood test if your cat has signs of hyperthyroidism or as part of an annual well visit. In many cases, a simple T4 level can indicate the condition. Still, a profile looking at free T4 and an enzyme TSH is beneficial.

Your cat’s blood panel is helpful to check your cat for kidney disease and other health issues. Hyperthyroidism and kidney disease are often linked and should be checked for.

Preventing Hyperthyroidism in Cats

This endocrine condition is not one that you can prevent. The critical part of managing hyperthyroidism is noticing the changes in your cat and seeking a diagnosis and treatment sooner rather than later. Annual blood screens can detect changes early and help your veterinarian handle the problem earlier.

5. Diabetes

Diabetes is another common endocrine disorder in cats. Up to 1% of cats will develop diabetes in their lifetime6. Left untreated, diabetes can lead to significant health complications, including diabetic ketoacidosis.

In diabetes, cats either don’t make enough insulin or they aren’t able to respond to insulin to transport glucose, a simple sugar molecule, into cells. Pets with diabetes are usually treated with injectable insulin, although newer treatments, such as Bexacat or Bexagliflozin, a daily chewable that helps regulate your cat’s glucose levels.

Signs of diabetes are:
  • Weight loss
  • Increased drinking (polydipsia)
  • Excessive urination (polyuria)
  • More frequent urination (pollakiuria)
  • Urinating outside of the litter box
  • Signs of a urinary tract infection, such as bloody urine (hematuria)
veterinarian weighs an overweight pet on a scale
Image Credit: Zhuravlev Andrey, Shutterstock

Diagnosing Diabetes in Cats

Your veterinarian will need to perform blood testing on your cat to diagnose diabetes, as well as a urinalysis. An elevated blood sugar or glucose level is not enough by itself to diagnose diabetes because many cats develop stress hyperglycemia in the veterinary setting, an elevated blood sugar level.

The urinalysis helps look for evidence of glucose in the urine. It also provides vital information: the presence of bacteria could suggest a UTI, while ketone could mean diabetic ketoacidosis.

Preventing Diabetes in Cats

The best way to prevent diabetes in cats is weight management. Your veterinarian can help you determine an ideal body weight for your cat. Dieting and exercise are as necessary for our cats as for people. You can reduce the risk of your cat developing diabetes by feeding a canned diet. Dry kibble is higher in carbohydrates than most canned foods, leading to weight gain and poor glycemic control.

6. Rabies

Rabies is virtually 100% fatal, and cats are the most likely domesticated animal to develop rabies. This virus is typically transmitted through saliva, and bites or scratches from an affected animal can pass on the infection.

In the United States, common reservoirs for the virus include:
  • Bats
  • Skunks
  • Raccoons
  • Foxes

Some cats with rabies become withdrawn and quieter than normal, while others can become irritable or excited. Affected animals can become aggressive. They may drool more as muscle spasms stop them from being able to swallow normally. Dilated pupils are common in rabies-infected cats.

Diagnosing Rabies in Cats

The only way to diagnose rabies in cats is by examining brain tissue in a lab. If your cat is suspected of having rabies, your veterinarian will generally recommend euthanasia and submitting samples to a laboratory. Sometimes, we aren’t sure if a cat has been exposed to rabies. They may be quarantined for some time, usually ten days to 6 months, to see if signs develop.

Preventing Rabies in Cats

Rabies vaccinations are vital to keeping our pets and ourselves safe. Depending on the vaccine type the veterinarian uses and the area you live in, rabies vaccines are usually suitable for 1 to 3 years.

If your car is potentially exposed to a rabid animal, get a rabies vaccine administered by a veterinarian immediately. Post-exposure rabies vaccines, given before the virus enters the nervous system, are often effective at preventing an animal from developing rabies.

7. Feline Infectious Peritonitis

Feline infectious peritonitis is caused by a mutated version of feline enteric (gut-related) coronavirus. Roughly 10% of cats with coronavirus will develop mutations that cause the virus to spread throughout their body7. (This is not the coronavirus that is commonly called COVID-19.)

Feline infectious peritonitis, or FIP, occurs when the body produces an intense inflammatory response in tissues where the virus occurs. Typically, signs are mild and non-specific, such as lethargy. Many cats develop abdominal effusion or a distended belly from fluid.

Cats tend to be affected rapidly, especially with the effusive type of FIP. The condition has historically been almost completely fatal, but newer treatments are effective in some cases. In the United States, it can be harder to get these medications because they aren’t currently approved for treating FIP.

woman brought her maine coon cat to the vet
Image Credit: Gorodenkoff, Shutterstock

Diagnosing Feline Infectious Peritonitis

Feline infectious peritonitis is hard to diagnose, and your veterinarian may suggest treatment based on your cat’s presentation and antibody levels for coronavirus. Other tests, such as PCR, may help diagnose FIP.

Preventing Feline Infectious Peritonitis

Limiting your cat’s possible exposure to coronavirus is the best way to reduce their risk of developing FIP. Please note that the mutated form of the coronavirus is not considered contagious. Still, the originating form is easily transmitted between cats through saliva and feces.

Practice good hygiene between cats and isolate new cats into your home until they are healthy. A FIP vaccine is on the market, but its effectiveness is questionable, so most veterinarians don’t use it. Keeping your cat healthy and vaccinating against other illnesses, such as feline distemper and feline leukemia, can help keep your cat healthier and may decrease the likelihood of them getting sick.

8. Heartworms

Heartworms are parasites transmitted by mosquitoes. Once your cat has been bitten by a mosquito-carrying heartworm larvae, the larvae begin to develop in the bloodstream. Cat heartworms are less common than dogs, with reported ranges between 5% to 20% of the rate of dogs infected in a given area.

Cats are not an ideal host for heartworms, so the parasite usually doesn’t live as long in cats as in dogs. They can cause significant disease, including sudden death. The most common sign of heartworms in cats is caused by the heartworm-associated respiratory disease (HARD) complex. They can have wheezing, coughing, and even develop hypertension.

Diagnosing Heartworms in Cats

It’s harder to diagnose heartworms in cats than in dogs. Blood tests looking for heartworm antibodies and antigens are often used. Still, they don’t pick up every case of heartworms, often due to the low worm burden your cat could have.

Radiographs (X-rays) can look for lung changes and heart enlargement, while your veterinarian might even see adult heartworms on an echocardiogram (ultrasound of the heart).

Preventing Heartworms in Cats

The best way to prevent heartworms is to use a heartworm prevention product for your cat every month. Popular brands include:

All it takes is one mosquito to transmit heartworms. Your cat could be indoors only and still get exposed.

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Frequently Asked Questions

What is the deadliest disease in cats?

Rabies is almost always deadly in animals that don’t receive immediate post-exposure vaccination. It is also deadly for people, so proper precautions should be implemented.

How can I prevent my cat from getting sick?

Work with your veterinarian to develop a plan for your cat that includes screening blood work and a urinalysis. Your vet can also help you decide what vaccines are core or essential for your cat based on their lifestyle.

Keep your cat away from potentially ill animals by keeping them inside. Use appropriate flea, tick, and heartworm prevention products monthly to reduce the risk of exposure.

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While not all diseases affecting our cats are preventable, an excellent preventative care plan goes a long way to keeping your cat healthy. Diseases can often be diagnosed earlier when treatment would be most effective.

Featured Image Credit: megaflopp Shutterstock

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