November 10, 2025, 10:14 am | Read time: 6 minutes

1. Cat Cold

One of the most common diseases in cats, especially among strays and outdoor cats, is cat cold. Experts use this term to describe certain respiratory and mucous membrane diseases in cats. In professional language, the terms “infectious feline rhinitis” or “feline pneumonitis” are also common. A cat cold is caused by various pathogens such as feline herpesviruses, caliciviruses, or bacteria like Bordetella or chlamydia.¹

Affected cats may show the following symptoms:

• watery, sticky eyes
• nasal discharge
• fever
• loss of appetite
• ulcers in the oral mucosa
• If a cat cold is not treated in time, fever and loss of appetite may occur. Bacterial causes of cat cold can be treated with antibiotics. Vaccinations are available against herpesviruses and caliciviruses.

Treatment: Bacterial causes of cat cold can be treated with antibiotics. Vaccinations are available against herpesviruses and caliciviruses.

2. Kidney Weakness

A saying among veterinarians is that the old cat and the sick kidney go hand in hand. Therefore, kidney weakness is one of the most common cat diseases. The kidneys are considered the cat’s weak spot. Many older animals develop chronic kidney insufficiency, where kidney function steadily declines. The disease manifests through symptoms such as:

• excessive thirst or increased drinking
• increased urination
• lack of appetite
• apathy (indifference)

Treatment: Although chronic kidney insufficiency is not curable, a special kidney diet can allow an affected cat to live many happy months or even years. Suitable diet food contains high-quality protein and low phosphorus to avoid burdening the damaged kidneys.²

3. Parasite Infestation

Parasite infestation itself is not a disease, but the pests can transmit disease-causing viruses or cause symptoms in the cat that resemble a disease. This is the case with worms, for example. Roundworms colonize the intestines and can be detected in the cat’s feces. A worm infestation leads to symptoms like loss of appetite, vomiting, and weight loss, and is treated with deworming.

But ectoparasites like ticks, fleas, and mites also cause different symptoms in cats. They are found on the skin or in the fur and can cause severe itching. Special spot-on preparations can protect your cat from these small pests. If the animal scratches frequently, has bald spots in its fur, or dandruff, it may indicate a parasite infestation.

4. Feline Distemper (FPV or FPLV)

Feline distemper is the most dangerous of the common diseases cats can contract. It is also called “feline parvovirus” or “panleukopenia.” It is a life-threatening viral infection that primarily affects young kittens. The cause of this severe disease is the feline panleukopenia virus (FPV or FPLV). Feline distemper manifests through symptoms such as:

• high fever
• fatigue
• refusal to eat
• sometimes bloody diarrhea

Treatment: There is no specific medication for this disease. Veterinarians primarily treat the symptoms, and the rest must be managed by the animal itself. If untreated, this cat disease can lead to death within hours, especially in young or pre-existing conditions. Adult, well-nourished cats usually cope better with the infection. A vaccine is available to prevent this severe disease.

5. Feline Leukemia (FeLV)

Feline leukemia is also among the most common diseases in cats. It is caused by a viral infection. Infection with the feline leukemia virus (FeLV) can lead to tumors and hinder blood cell formation in the bone marrow. Infected cats show nonspecific symptoms, including:

• fever
• weight loss
• increased fatigue

Treatment: The disease is also known as “feline leukosis” and is considered incurable. Since affected cats have weakened immune systems, they are susceptible to further infectious diseases and should be regularly checked by a veterinarian. Good to know: There is a vaccine against the feline leukemia virus.

6. Dental Issues (FORL)

The most common dental disease in cats is FORL—now often referred to as “resorptive lesions” (RL). Studies show that up to 70 percent of all cats are affected, especially those over three years old. However, few are presented due to dental symptoms—the number of unreported cases is high. Because: Cats with tooth pain often continue to eat—but that doesn’t mean they are pain-free.

The disease begins invisibly in the area of the tooth root, where the body’s own cells (odontoclasts) attack the tooth substance. Visible symptoms such as exposed tooth necks, reddened gums, or broken teeth often appear late—but pain occurs early.³

Typical signs of FORL are:

• chewing on one side, head tilt
• twitching while eating, increased salivation
• refusal to eat, especially cold or hard food
• unpleasant mouth odor
• visible tooth loss or gum overgrowth

A definitive diagnosis is only possible through dental X-rays under anesthesia. It often becomes clear that seemingly missing teeth are still present with inflamed root remnants in the jaw. The only effective therapy: surgical removal of the affected teeth, possibly with crown amputation in type-2 resorptions.

Experts recommend regular dental examinations and veterinarians trained in dental care (COHAT—Comprehensive Oral Health Assessment and Treatment).⁴

More on the topic

Animal Health How to Measure a Cat’s Fever and When to See the Vet

Oral Hygiene Causes and Treatment of Bad Breath in Cats

7. Diabetes Mellitus

Diabetes is one of the most common metabolic diseases in cats and occurs mainly in overweight animals over ten years old. About 70 to 80 percent of affected cats suffer from type-2 diabetes, where the cells no longer respond properly to insulin.

Classic symptoms are:

• excessive thirst (polydipsia)
• frequent urination (polyuria)
• increased appetite with simultaneous weight loss (polyphagia)
• muscle weakness, especially in the hind legs (plantigrade gait)
• fatigue, lethargy

After diagnosis by the veterinarian, therapy usually involves insulin specifically approved for cats. Alternatively, oral medications can be used to promote sugar excretion. Regular blood sugar checks are important—trained owners can also perform these themselves.⁵

Diet plays a crucial role: Protein-rich and low-carbohydrate diets significantly improve blood sugar control. Overweight cats should lose weight, as even a weight gain of less than two kilograms can halve insulin sensitivity.

Important: With early diagnosis, remission is possible in some cats—they no longer need medication, but remain susceptible and must continue to be monitored.⁶

Conclusion

Not only visible changes but also subtle symptoms like altered eating behavior, increased thirst, or uncleanliness can be early signs of a serious illness. Early diagnoses and regular veterinary checks—including dental X-rays—help prevent unnecessary suffering.