Common Cat Diseases and How to Recognize Them

Learn about some common feline conditions.

There are a few conditions that are commonly seen in cats, and it's crucial that you know their primary signs. The sooner you realize something is going on, the faster you can take your cat to the vet, get a diagnosis, and start on treatment.


The diagnosis of this condition has steadily climbed since the 1980s, and it's become one of the most commonly diagnosed feline conditions there is. It's an overactive thyroid gland, usually caused by benign (non-cancerous) tumors. Sometimes, it is caused by cancerous tumors.

The main signs seen in cats with hyperthyroidism include:

  • Fast weight loss
  • Sharply increased appetite
  • Hyperactivity that often shows up as restlessness, particularly at night
  • Increased vocalizations
  • Trying to get people food or eating non-food items
  • Lumps in the thyroid gland (usually not apparent to owners but can be felt by a veterinarian)
  • Increased water consumption

Other signs of hyperthyroidism that are not obvious to owners but can be found through a thorough physical exam or testing include:

  • High blood pressure
  • Fast heart rate
  • Secondary kidney dysfunction

If hyperthyroidism is left untreated, the cat will suffer from irreversible heart and kidney disease and, ultimately, death.

Hyperthyroidism is diagnosed through bloodwork. There are three main ways to treat it:

  • Lifelong oral (or transdermal) medication
  • Radioactive iodine therapy to target the tumor cells in the thyroid
  • Surgery to remove affected thyroid gland

Diabetes Mellitus

This condition is common in middle-aged and older cats, especially those that are obese, to begin with. The signs that owners identify most often include:

  • Extreme thirst and increased urination (big clumps of urine in the box or inappropriate urination of significant amounts of urine outside the box)
  • Weight loss
  • Muscle loss over the head and back
  • Decreased or increased appetite
  • Lethargy
  • Weakness

Cats that aren't treated for their diabetes mellitus can develop life-threatening diabetic ketoacidosis.

Diagnosis of diabetes in cats is done through bloodwork and urinalysis. Treatment is diet change and, usually, daily or twice daily insulin injections.

Heart Disease

Heart disease in cats is one condition that is commonly "silent." That means that there are often not many signs that it's present until a severe complication occurs. There might be a heart murmur, or abnormal heart sounds, identified when a veterinarian listens to the cat with a stethoscope, but only around 50% of cats even have that.

Some signs you could possibly see if your cat has heart disease include:

  • A racing heart rate
  • Panting
  • Increased breathing rate
  • Blue-tinged gums and skin
  • Episodes of passing out

Sudden extreme pain and paralysis of the rear legs (saddle thrombus) can occur as a result of a blood clot from heart disease.

Sudden death with no prior signs of illness is also a common occurrence with feline heart disease.

Heart disease is diagnosed with chest x-rays and ultrasound, and treatment includes many different heart medications based on the exact condition, diuretics, and sometimes oxygen therapy.

Kidney Disease

Kidney disease is prevalent in cats. It can occur acutely in cases of toxin exposure or chronically in cases of age, chronic dehydration, and other factors. Some cats are congenitally prone to the condition.

The signs of kidney disease in cats include:

  • Increased thirst and urination
  • Inappropriate urination of large amounts of urine
  • Weight loss
  • Decreased appetite
  • Foul breath
  • Lethargy

Cats with kidney disease develop many other secondary situations, like high phosphorus, low potassium, and anemia.

Kidney disease is diagnosed through blood work and sometimes x-rays and ultrasound. Treatment includes low-protein diet, fluid therapy, and sometimes potassium supplements, phosphorus binders, anti-nausea or appetite stimulant medications, and others as needed.


Many types of cancer are common in cats, including oral squamous cell carcinoma and lymphosarcoma of the GI tract.

Signs of cancer in cats can vary wildly depending on the body system involved, and include:

  • Decreased appetite
  • Weight loss
  • Lethargy
  • Lumps or bumps on the body
  • Drooling or foul breath
  • Vomiting and diarrhea
  • Trouble breathing and coughing

Of course, there are plenty of other conditions to watch out for in cats. If you see any change in appetite, elimination, gait, or behavior, visit a vet with your cat right away.

Cancer is diagnosed with blood work, x-rays, ultrasound, MRI, CT scan, and exploratory surgery. Treatment is specific to the type and location of cancer as well as the damage already done to organ function and whether there has been metastasis or spreading of the cancer.

Disclaimer: This website is not intended to replace professional consultation, diagnosis, or treatment by a licensed veterinarian. If you require any veterinary related advice, contact your veterinarian promptly. Information at is exclusively of a general reference nature. Do not disregard veterinary advice or delay treatment as a result of accessing information at this site.