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List of Common Indoor and Outdoor Cat Illnesses and Their Symptoms

Cats will instinctually hide when they don't feel well, making it very challenging for even the most attentive pet parents to recognize when their feline friend is sick. In today's post, our Los Angeles vets share some common cat illnesses, their symptoms, and diagnosis procedures.

Your Cat's Health

Our feline companions are stoic creatures who are excellent at concealing signs of illness. When cats are feeling unwell, they will often hide. This can make determining when your cat is sick difficult. However, as a pet parent, it is critical to monitor your pet's health and take him or her to the vet if he or she begins to feel ill. The following are some of the most common illnesses seen in both indoor and outdoor cats.

Common Cat Illnesses

When it comes to cats, some illnesses are more common than others, and the illnesses most commonly seen in indoor cats aren't always the same as those seen in outdoor cats. Nonetheless, there are a few common feline illnesses that all pet owners should be aware of. Here are some of the most common illnesses seen in cats by our Los Angeles veterinarians.

Upper Respiratory Infections (Cat Colds)

Viruses and bacteria such as feline herpesvirus and feline calicivirus can cause your kitty to develop upper respiratory tract infections that affect their sinuses, nose, and throat.

These illnesses are easily transmitted between cats who live in multi-cat households, and shelters, or who spend time outside where they may come into contact with other cats. Normal activities such as grooming, sharing a food or water bowl, or coughing and sneezing can spread feline herpesvirus and feline calicivirus. Cats infected with the virus can easily spread the disease to other cats in the household or in the neighborhood. Upper respiratory illness in cats is characterized by the following symptoms:

  • Coughing
  • Congestion
  • Drooling
  • Sneezing
  • Gagging
  • Fever
  • Loss of appetite
  • Nasal discharge

Feline Immunodeficiency Virus (FIV)

Feline Immunodeficiency Virus or FIV as it is commonly called is most often seen in male outdoor cats with a tendency to fight. This potentially serious cat illness is often passed along through bites sustained during fights, although in rare cases it can be passed from a female cat to her kittens.

FIV is a slow-acting virus and in some cases, symptoms may not show up until years after the initial infection occurred. That said, FIV can severely weaken your cat's immune system once the disease takes hold making your feline friend susceptible to a number of serious secondary infections.

With appropriate treatment, infected cats that are kept in an indoor, stress-free environment can live comfortable lives for a number of months or years before the disease reaches its chronic stages.

If your cat has FIV, symptoms may not appear for months or years, or they may appear intermittently. If your cat exhibits any of the following symptoms, he or she may be suffering from Feline immunodeficiency virus (FIV) and should seek veterinary care as soon as possible to help prevent symptoms from worsening.

Common symptoms of FIV include:

  • Enlarged lymph nodes
  • Fever
  • Anemia
  • Unexplained weight loss
  • Poor grooming
  • Disheveled coat
  • Lack of appetite
  • Diarrhea
  • Abnormal appearance
  • Inflammation of the eye
  • Inflammation of the gums and mouth 
  • Skin redness or hair loss
  • Wounds that don’t heal
  • Sneezing
  • Discharge from eyes
  • Runny nose
  • Frequent urination
  • Straining to urinate
  • Urinating outside of the litter box
  • Behavior change


If your cat is unable to produce enough insulin to balance glucose levels or blood sugar it will develop diabetes mellitus. Left untreated, diabetes in cats can shorten their lifespan and lead to nerve disorders, numerous health issues, and severe emergency situations requiring immediate veterinary care. Treatment for diabetes in cats is focused on managing the disease rather than a cure and may include insulin injections. Signs of diabetes in cats include:

  • Increased urination
  • Dehydration
  • Loss of appetite
  • Coma
  • Increased thirst
  • Increased appetite
  • Vomiting
  • Motor function problems


Our veterinarians frequently see a variety of cancers in cats. Cancer begins in a cell, then attaches to the tissue beneath the skin and potentially spreads to other areas. Cancer in cats may be treatable if detected early. Cancer symptoms in cats can include:

  • Marked increase or
  • Decrease in appetite
  • Lumps that change in size or shape
  • Difficulty urinating 
  • Bad breath
  • Sores that do not heal
  • Chronic weight loss
  • Straining during bowel movements
  • Unexplained bleeding
  • Unexplained discharge

Early detection is essential for good outcomes when it comes to treating cancer in cats. Some other factors which influence the success of cancer treatment include the type of cancer, the extent of its spread, and the location of the tumor. Recommended treatments for cats diagnosed with cancer include surgery, chemotherapy, and radiation.

What To Do If Your Cat Is Sick

If your cat is showing signs of any of the illnesses listed above, it's important to seek veterinary care as soon as possible. Many cat illnesses progress quickly and can become very serious quickly.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Do you think that your cat may be sick? Contact our Los Angeles vets at Shatto Veterinary Center today to book an examination for your kitty.

Welcoming Cats & Dogs to Our Animal Hospital 

Shatto Veterinary Center welcomes cats, dogs, and their people to our clinic! Our experienced vets are passionate about the health of Los Angeles companion animals. Get in touch today to book your pet's appointment.

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