25 Most Common Cat Diseases, Parasites and Health Problems

According to the American Veterinary Medical Association, there are more than 58 million cats owned in the United States alone.¹ There's no doubt about it — we love our cats! And whether we're sharing memes or snapping pictures of our favorite feline, we just love talking about them. So let's talk about our cats' health.

We all want to keep our feline friends healthy and happy — and that means watching out for common cat diseases and health problems that could affect your cat. Below, we outline the 25 most common cat diseases so you'll know what to look for to keep your cat healthy.

1. Chronic Kidney Disease (CKD)

Also known as renal insufficiency, chronic kidney disease (CKD) occurs due to irreversible, progressive loss of kidney function. The condition is prevalent in senior cats, but cats of any age can be affected. Pet owners often first notice increased thirst, increased urination and weight loss in cats with CKD.

2. Cat Acne

Feline acne is common in cats of all ages. It usually presents as small, skin-colored bumps on the chin and the skin adjacent to the lips, but some cats may develop pustules, swelling of the chin, itching and pain. Most cases of feline acne do not require treatment, but severe cases may benefit from antibiotics to control the infection.

3. Diabetes Mellitus

Similar to humans, cats can develop diabetes, most commonly Type II diabetes, also known as non-insulin-dependent diabetes. The disease is typical in male cats aged 10 to 13 years, particularly cats who are overweight or obese. Pet owners often first notice symptoms such as increased thirst, increased urination, increased appetite and weight loss.

4. Eosinophilic Granuloma Complex (EGC)

Eosinophilic Granuloma Complex (EGC) is an umbrella term for a group of skin reactions that occur in cats, typically secondary to an underlying allergy. One of the most common presentations is erosions or ulcerations on the lips. Other lesions can include raised, thickened, red areas on the abdomen, inner thighs, around the anus or on the footpads. Often, the lesions are itchy and uncomfortable.

5. Feline Immunodeficiency Virus (FIV)

FIV is an immunosuppressive virus spread between cats primarily through bite wounds. Affected cats often have no symptoms for months or years after infection. Cats with FIV eventually progress to acquired immunodeficiency syndrome (feline AIDS), making them susceptible to secondary diseases.

6. Feline Infectious Peritonitis (FIP)

FIP is a frequently fatal viral disease in cats caused by certain strains of feline coronavirus. It is most common in young cats less than 2 years of age, though geriatric cats are also susceptible. Purebred cats, male cats and cats housed in high-density facilities such as shelters and catteries are at higher risk of developing FIP. The first symptoms pet owners usually notice include non-specific signs such as weight loss, lethargy, depression and fever.

7. Feline Leukemia Virus (FeLV)

Feline leukemia virus is one of the most common infectious diseases in cats, with an estimated 2% to 3% of all cats in the United States infected.² The virus is spread from cat to cat through bite wounds, mutual grooming or sometimes even by sharing dishes and litter boxes, although this is rare. Kittens are most susceptible to FeLV infection. Cats with FeLV are more prone to cancer, blood disorders and secondary infections. Feline leukemia is preventable through vaccination.

8. Feline Lower Urinary Tract Disease (FLUTD)

FLUTD is a catch-all term used to describe a variety of common bladder and urethra conditions in cats. While cats of any age can be affected, feline urinary tract disease is typical in middle-aged, overweight, indoor cats. Symptoms of FLUTD include inappropriate urination, straining to urinate, frequent trips to the litter box, urinating in small volumes, blood in the urine and vocalizing while urinating.

9. Feline Panleukopenia Virus (Feline Distemper)

Feline panleukopenia virus is a highly contagious virus found worldwide. It is also known as feline distemper or feline parvovirus. Young kittens are most susceptible to feline panleukopenia, but unvaccinated cats of any age can be affected. The virus attacks rapidly dividing cells in the intestine, bone marrow and lymph nodes, leading to diarrhea, anemia and a deficiency of white blood cells (panleukopenia). Feline panleukopenia is preventable through vaccination.

10. Fleas

Fleas are small insects that feed on blood, and they are extremely common worldwide. They are the most common external parasites of cats and dogs. The cat flea, Ctenocephalides felis, can infest both cats and dogs. Not only can fleas cause itching and discomfort through their bites, but they can also spread diseases to your cat, such as tapeworm, Bartonella and Rickettsia. Many cats with fleas show no symptoms other than flea dirt: small, reddish-brown flecks of flea feces found in the coat.

11. Hyperthyroidism

Hyperthyroidism occurs when the thyroid gland overproduces and secretes excess thyroid hormone. This condition is typical in middle-aged and senior cats. Symptoms of hyperthyroidism include weight loss, ravenous appetite, excessive drinking and urinating, vomiting and increased vocalization. Multiple treatment options exist, including medication, diet and radioactive iodine therapy.

12. Hypertrophic Cardiomyopathy (HCM)

HCM is the most commonly diagnosed cardiac disease in cats. The condition causes a progressive thickening of the muscular walls of the heart, decreasing its ability to pump blood effectively. Congestive heart failure or the development of blood clots can occur secondary to HCM. Many cats with HCM have no symptoms initially, while others may develop a heart murmur or an abnormal heart rhythm. Cats with congestive heart failure may experience symptoms such as coughing, difficulty breathing, lethargy or exercise intolerance.

13. Inflammatory Bowel Disease (IBD)

IBD is the chronic irritation and inflammation of the gastrointestinal (GI) tract. The exact cause of IBD is unknown, but it is thought to be due to a combination of genetics, dietary factors, environmental factors, gut bacteria and abnormal immune system responses. The condition most commonly affects middle-aged and older cats. Symptoms include vomiting, diarrhea, weight loss, changes in appetite, flatulence, poor body condition and abdominal pain.

14. Intestinal Parasites

Intestinal parasites are prevalent in cats of all ages. Roundworms are the most common intestinal parasite of cats, and according to the Companion Animal Parasite Council, 1 in 20 cats tested positive for roundworms in 2022.³ Other common intestinal parasites of cats include hookworm, tapeworm, coccidia, giardia and toxoplasma. Many cats with intestinal parasites show no symptoms, while others may show signs such as diarrhea, vomiting, weight loss, dull coat and loss of appetite.

15. Lymphoma

Lymphoma is a cancer of the lymphatic system and is one of the most commonly diagnosed cancers in cats. Infection with FeLV or FIV can predispose a cat to develop lymphoma. Lymphoma can be present in many areas of a cat's body, but gastrointestinal lymphoma (also called alimentary lymphoma) is the most common. Usual signs of gastrointestinal lymphoma include weight loss and loss of appetite.

16. Mammary Tumors

Mammary tumors are typical in unspayed females or those spayed after their first heat cycle. In cats, approximately 85% of mammary tumors are malignant.⁴ Pet owners first notice a lump or mass in the mammary chain, or the veterinarian may palpate the mass during a routine examination. Surgery is the recommended treatment, sometimes in conjunction with chemotherapy.

17. Mast Cell Tumor

Mast cell tumors are the second most common skin tumors in cats. They can occur anywhere on the body but are mainly found on the head and neck, especially at the base of the ears. They typically appear as a firm, hairless, raised nodule, although their appearance can vary. Surgery to remove the tumor is the recommended treatment option in most cases.

18. Obesity

According to the Association for Pet Obesity Prevention, 59.5% of cats are classified as overweight or obese.⁵ While the internet has popularized pet obesity with fun nicknames and memes, feline obesity is no laughing matter. It increases a cat's risk of developing many other diseases, including diabetes mellitus, osteoarthritis, heart disease and cancer. Obesity may also significantly impact a cat's life span and quality of life.

19. Osteoarthritis

Arthritis is incredibly common in cats, with one study finding that 90% of cats over the age of 12 had evidence of arthritis on X-rays.⁶ Unfortunately, cats are very good at hiding their pain, and arthritis often goes undetected. Pet owners may notice symptoms such as hesitancy to jump, difficulty using stairs, an increase in sleeping and a dislike of being touched in certain areas.

20. Pancreatitis

Once thought to be rare in cats, we now know that pancreatitis is quite common. Inflammation of the pancreas can occur due to concurrent diseases such as diabetes mellitus, hepatic lipidosis and inflammatory bowel disease. In many cases, no inciting cause for pancreatitis is found. Symptoms include lethargy, loss of appetite, weight loss and vomiting.

21. Periodontal Disease

Periodontal disease is the inflammation and infection of the structures that support the teeth, including the gums and bone. Studies show that between 50% and 90% of cats over the age of 4 have some form of dental disease.⁷ Many cats show no symptoms of periodontal disease until it becomes severe. Symptoms noticed by pet owners include bad breath, drooling, dropping food, reluctance to eat hard foods, bleeding gums and oral pain.

22. Pyometra

Pyometra is an infection of the uterus that occurs in unspayed females. Symptoms usually start within six weeks of the cat's last heat cycle and can include lethargy, depression, fever, increased drinking and urinating, loss of appetite, vaginal discharge, abdominal pain and vomiting. Pyometra is an emergency condition and surgery to remove the infected uterus is strongly recommended.

23. Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) is one of the most common skin tumors and the most common oral tumor in cats. As a skin tumor, ultraviolet light plays a direct role in its development, and it is most common on sparsely-haired areas of white and light-colored cats. As an oral tumor, SCC typically occurs at the base of the tongue. Surgical removal is recommended for both forms of squamous cell carcinoma.

24. Upper Respiratory Infection (URI)

Upper respiratory infections are prevalent in cats of all ages, especially kittens. Cats at the highest risk for URI include those from the shelter, outdoor cats and cats housed in crowded conditions. Symptoms of URI include ocular and nasal discharge, sneezing, coughing, fever, lethargy and loss of appetite.

25. Urethral Obstruction

Also known as a "blocked cat," urethral obstruction is a potentially life-threatening condition in which urine outflow is obstructed. It can be caused by mucus plugs, urinary stones, inflammation, edema, strictures, cancer and urethral spasms. Urethral obstruction is most common in male cats, particularly overweight males. Symptoms include unproductive straining, vocalizing while attempting to urinate, vomiting, loss of appetite, lethargy, abdominal pain, weakness and collapse.

Scheduling a Vet Exam

If you suspect your cat is experiencing one of these conditions, it's important to see your veterinarian for an examination. Because many of these conditions have similar symptoms, it is crucial that you do not attempt to self-diagnose your pet.

Your veterinarian will perform a full head-to-tail physical examination and may recommend some additional diagnostic tests. Once your cat's condition has been appropriately diagnosed, your veterinarian can recommend a treatment plan that is best suited to your cat's needs.

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Author Bio

Dr. Elizabeth Racine is a small animal general practice veterinarian and freelance writer. She covers both human and veterinary medicine with a special interest in nutrition, internal medicine, and veterinary behavior.