Common Cat Illnesses and How to Identify Them | Catzio

Common Cat Illnesses and How to Identify Them

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Domestic animals are susceptible to lots of different sicknesses. Some are short-lived and don’t inflict too many symptoms on your pet. Others may not cause any symptoms at all, causing your pet to only carry the disease rather than suffer from it. Still, some medical conditions can result in discomfort, even pain, for pets like cats. 

Cats are known to have sensitivities to several illnesses. They range from those that affect only the feline body to diseases that can jump to humans, too. For greater insight into what medical conditions to be aware of for your fur-baby and various cat illnesses’ symptoms, see the information below.

Understanding Respiratory Diseases in Cats


Just like their human counterparts, kitties are susceptible to catching various respiratory illnesses. Unfortunately, not all these conditions are as simple as a passing cold. Below are examples of three infections that affect cats’ respiratory tracts and are likely to cause more damage than a few sniffles and sneezes: 

  • Feline rhinotracheitis virus: Cats that live with this condition usually experience significant inflammation of the airways (i.e., the nose, windpipe, or trachea). Unfortunately, the virus responsible for the infection, herpesvirus-1, can also damage the reproductive system’s health and cause pregnancy complications.

    •  Note: Herpesvirus-1 causes 80-90% of all upper respiratory diseases in cats.

  • Feline calicivirus: Cats that regularly visit boarding facilities or have just been adopted from a breeding colony or shelter are the most likely to have this infection. Although it’s highly contagious, it’s not a concern for humans, and most cats experience a full recovery after the illness.

    • Note: Symptoms will differ based on the specific strain of calicivirus. In general, you’ll notice the infection based on behaviors typical of a mild cold (e.g., sneezing, congestion, fever, drooling). If you observe ulcers in the mouth or severe behavioral changes like a notably weaker appetite, consult with your vet, as the strain may be more serious. 

  • Pneumonitis (chlamydia): Fortunately, this cat illness is quite rare, especially compared to the first two. Whether the infection is either of the two kinds described below, the most common pneumonia symptoms include nasal discharge (often yellow), abnormally fast heartbeat and breathing, and a fever.

    • Aspiration: This form of pneumonia occurs as a direct consequence of your cat mistakenly inhaling a foreign object into their lungs. The object will irritate the lungs’ sensitive tissue linings, leading to symptoms like vomiting or a secondary lung infection due to bacteria being re-inhaled after regurgitation. 


    • Infectious: These pneumonia infections are caused by the inhalation of harmful microorganisms. Aside from bacteria, this includes viruses, protozoa, and fungi. 



It can be tough to tell all these respiratory cat illnesses apart. If you’re seeing any signs of complications with your cat’s breathing, it’s best to take it to the veterinary clinic right away. Quick action ensures that there is no possibility of the infection worsening before it’s detected. 


Identifying Feline Leukemia Virus (FeLV)

This virus affects both wild and domestic cats, and the rate of infection rises with denser cat populations. So, if you live in an area with a high concentration of outdoor cats or have a multi-cat household, your cats’ chances of contracting FeLV are higher than average. 


(Owners with single cats see infection rates as low as 1%, but the probability jumps to 20+% in multi-cat households. Although, in these studies, owners who lived with several cats did not take specific preventative measures to reduce or eliminate the chances of infection.)



Luckily, cats in North America and Europe have a relatively low chance of being infected. However, you should still know what to look for in case anything goes wrong. The most recognizable symptoms of FeLV are as follows:

  • Paleness on the gums

  • Yellowing of the tissues in the mouth and whites of the eyes

  • Swollen lymph nodes

  • Unusual weight loss

  • Disinterest in eating

  • Respiratory problems, ranging from difficulty breathing to upper respiratory tract infections

  • Weakness or lethargy

  • Ulcers in the mouth

  • Fever

  • Diarrhea

  • Reproductive complications

  • Unhealthy coat

It should be noted that 85% of cats diagnosed with FeLV succumb to the infection within three years of confirmation of the disease. Compounding health impacts like anemia and immunosuppression are often the culprits behind the cat’s medical decline, both caused by FeLV. 


For this reason, it is best to take immediate action upon noticing any of the cat disease symptoms above. The chances of a positive outcome rise significantly with early detection and treatment. 



Lastly, FeLV is quite easily spread, as the virus can be present in the infected cat’s saliva, urine, nasal discharge and secretions, feces, and milk, in the case of nursing cats. If you suspect your cat is infected, quarantine it as soon as possible and clean the area to prevent the sickness from spreading in the house. 

Recognizing Urinary Tract Diseases in Cats

Another area of the feline body that is most often affected by the disease is the urinary tract. Cats are vulnerable to quite a few infections and mishaps in this region. Yet, the primary illness you should be wary of is feline lower urinary tract disease (FLUTD), once known as “feline urological syndrome,” or FUS.


This illness can manifest from a variety of causes, including behavioral issues. For example, cats under abnormal stress levels are at a higher risk of developing FLUTD. So, keep an eye on your kitty if you’ve just made a drastic change to your daily routine or introduced another pet in the household. 


Another behavior that may induce FLUTD is excessive drinking of water. Too much water paired with a weak bladder is an easy recipe for incontinence, another common cause of FLUTD. If you suspect that your kitty is a bit too keen on sipping from their bowl throughout the day, try to manage their water supply more closely to prevent infections. 



You’ll be able to tell that your cat has FLUTD by observing any of the following urinary illnesses in cats symptoms:

  • Straining or inability to urinate. Note that this may also manifest in the following ways: 

    • Abnormally long potty breaks in the litter box

    • Excessive trips to the litter box

    • Crying or displaying other signs of pain during urination.

  • Hard, swollen abdomen

  • Excessive genital licking

  • Inability to control urination

  • Avoidance of litter box

  • Excessive drinking

  • Urine has strong ammonia smell

  • Lethargy

  • Vomiting


If you see any of these issues, notify your veterinarian right away, especially if your cat shows signs of pain during urination. Such behavior can indicate an emergency, and you don’t want to give the problem time to worsen due to inaction. 

Sick Cat Symptoms that Indicate Zoonotic Diseases

As is the case with many domestic pets, there is always a chance of your fur-baby transmitting a zoonotic disease to you. This means that the microorganism, such as Bartonella henselae (the cause of cat scratch disease, discussed below) or parasite can make your cat sick, then move onto you and inflict similar or worse symptoms. 


One of the best examples of zoonotic illnesses spreading from cats to humans in a single household is a flea infestation. Fleas can live in the home’s flooring or furniture, only jumping onto the organisms’ when they want a bloodmeal. Because of this behavior, you’re just as likely to become a target for the insects as your kitty. 


In these cases, zoonotic diseases such as Lyme Disease quickly spread throughout the home. Yet, one factor that separates insect-borne zoonotic sicknesses from others is that your cat doesn’t transmit it directly. On the other hand, illnesses like cat scratch disease (CSD) can transfer straight from your fur-baby to you. 


CSD is a bacterial disease that infected cats carry in their saliva and potentially pass on to fleas. If the sick cat happens to bite or scratch you or even licks one of your open wounds, see your doctor as soon as possible. Most people tend to recover after a few months. However, immunocompromised individuals may suffer from more extreme symptoms like eye, heart, or brain infections. 



Approximately 40% of cats are estimated to have CSD yet show no symptoms whatsoever. It’s best to schedule an annual checkup for your kitty for preventative care and not wait for any signs to arise. Secondly, contact your doctor if you’re displaying any of the following signs after a bite or scratch:

  • Fever

  • Joint and muscle soreness

  • Headache

  • Fatigue

  • Loss of appetite

Cats are vulnerable to a variety of diseases that can harm both their and your health. Some of the most common illnesses include those that affect the respiratory system and urinary tract, feline leukemia, and many zoonotic sicknesses. 



With this guide, you are equipped to identify these health problems’ signs and get the condition treated as soon as possible, ensuring your cat’s wellbeing for years to come.  

About the Author

Jazmin “Sunny” Murphy began writing informal scientific content on nature and animals in 2015. Four years later, she launched her freelance career as a digital content and copywriter. This work merges her academic perspective, rooted in her B.S. Zoology, and professional experience as a veterinary tech, university research assistant, and more with relevant marketing, SEO, and engagement techniques across various industries. Jazmin now covers pet care, pest control, cannabis, outdoor recreation, STEM research and news, and product reviews across several niches.

About the Author

My name is Jazmin "Sunny" Murphy, and I am a science communicator and web content writer. Since 2015, I've been producing scientific content that is written in plain English. My love for life science has influenced my professional and academic aspirations since I was a kid. I hold a Bachelor of Science in Zoology and 21 units of a Master's education in Environmental Policy & Management (concentration: Fish and Wildlife Management). You can learn more about me and my science writing and reporting work at my website, Black Flower Writing Services.

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