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Common Cat Illnesses & Their Symptoms

Cats are incredibly good at hiding when they aren't feeling well. Here our Crystal Lake vets discuss some of the most common illnesses that a cat might experience, their symptoms and what to do if your cat experiences any of the following conditions. 

What cat illnesses are most common?

Illnesses can happen anytime when it comes to our feline friends and cat owners must always be prepared for this. Cat parents must also be aware of their cat's behavior as cats tend to isolate themselves out of instinct when ill. Here are 3 common cat illnesses to be on the lookout for, and their symptoms.

Upper Respiratory Infections

Viruses and bacteria can cause infections in your cat’s upper respiratory tract, sinuses, nose, and throat.

Frequently seen in multi-cat households and shelters, cats can contract feline herpesvirus and feline calicivirus through simply sharing a food or water bowl, coughing, sneezing or grooming.  Once a cat has contracted the virus it can then easily go on to transmit it to other cats.

Symptoms of upper respiratory illness in cats include:

  • Coughing or gagging
  • Sneezing
  • Fever
  • Decreased or lost appetite
  • Runny nose or nasal discharge
  • Congestion or drooling


If your cat doesn’t produce enough insulin to balance glucose levels or blood sugar, diabetes mellitus results. Poorly controlled diabetes can shorten your cat’s lifespan and lead to nerve disorders, numerous health problems, and severe emergency situations. If your cat is diagnosed with diabetes, there is no cure but your vet will be able to work with you to determine a treatment plan that includes managing the condition and can include insulin injections.

Left untreated, diabetes can lead to several serious symptoms, including:

  • Thirst
  • Increased urination
  • Increased appetite or loss of appetite
  • Vomiting
  • Dehydration
  • Motor function problems
  • Coma
  • Death


There are various types of cancer that can affect a wide range of cells and organs in your cat’s body. The disease first starts to grow within a cell, before attaching to the tissue underneath the skin and potentially spreading to other areas of the body.

Symptoms of cancer in cats may include:

  • Lumps or bumps that change in size or shape
  • Sores that do not heal
  • Odor from the mouth
  • Unexplained bleeding
  • Marked increase or decrease in appetite
  • Chronic weight loss
  • Difficulty urinating or defecating
  • Unexplained discharge

Feline Leukemia Virus (which cats can be vaccinated against) is a common contributor to cancer in cats. Other potential causes of cat cancers include toxins in the environment. If detected early during a physical exam, cancer in cats may be able to be treated.

Early detection is key when it comes to treating cat cancers. Other factors which influence the success of treatment include the type of cancer, the extent of its spread, and the location of the tumor. 

If your cat is diagnosed with cancer there are multiple treatment options such as surgery, radiation, or chemotherapy that are used to help treat the illness.

What you should do if your cat is ill

If you notice any of the above symptoms in your cat you should schedule a veterinary appointment as soon as possible. Many cat illnesses progress quickly and can become very serious in just a short period of time.

At Companion Animal Hospital in Crystal Lake, our compassionate emergency vets extend the routine services provided by your primary care veterinarian. We work with your vet to provide first-rate specialty and emergency care for pets in Crystal Lake.

If you are concerned that your cat may be experiencing symptoms of one of the above conditions, be sure to contact your vet. If your cat is experiencing an emergency, please contact us for assistance.

New Patients Welcome

Companion Animal Specialty and Emergency Hospital is accepting new patients! Our specialists and experienced emergency veterinarians are passionate about restoring good health to animal companions in Crystal Lake.

Contact Us

Contact (815) 479-9119