Wary of a Wandering Cat? How to Spot Signs of Illness in Strays


A stray cat is a cat that lives outdoors without any human owners. Stray cats often live in colonies with other stray cats and rely on the environment to meet their basic needs. While some stray cats appear healthy, others may suffer from infectious diseases due to their lack of regular veterinary care, shelter, and nutrition.

Common diseases found in stray cat populations include upper respiratory infections, flea and tick-borne illnesses, feline immunodeficiency virus (FIV), feline leukemia virus (FeLV), rabies, toxoplasmosis, and parasites. Identifying whether a stray cat is sick is important to prevent the spread of disease to other cats and even to humans in some cases.

By recognizing the signs and symptoms of illness in stray cats, individuals can make informed decisions about how to humanely and safely interact with these community cats. Additionally, trap-neuter-return programs rely on assessing the health of cats before returning them to their outdoor homes.

Physical Symptoms

There are some common physical symptoms that may indicate a stray cat is sick. These include:

An unkempt coat. Sick cats often stop grooming themselves regularly, so their fur may appear matted or dirty 1.

Nasal discharge. Thick mucus or pus draining from the nose could signal an upper respiratory infection 2.

Eye discharge. Green, yellow, or reddish discharge draining from one or both eyes may indicate conjunctivitis or another eye condition 3.

Limping. Lameness or difficulty walking can be caused by injuries or arthritis 2.

Poor body condition. Thin or emaciated cats may have trouble finding food, dental disease, parasites, or other conditions affecting appetite 3.

Skin lesions. Sores, scabs, and bald patches can indicate fungal or bacterial infections, mites, fleas, or allergies 1.

Behavioral Symptoms

There are several behavioral symptoms that may indicate a stray cat is sick. One of the most common is lethargy or low energy levels. A sick stray will often have less energy and be less active than usual. They may sleep more often and be slower moving when awake (Source: https://vcahospitals.com/know-your-pet/recognizing-signs-of-illness-in-cats).

Lack of appetite is another potential sign of illness in stray cats. Healthy cats have a strong appetite and eat frequently throughout the day. A stray that has suddenly lost interest in food or is eating much less may have an underlying medical issue (Source: https://www.thesprucepets.com/cat-behavior-changes-554050).

Increased aggressiveness like hissing, growling, swatting, or biting can also indicate a stray is not feeling well. Pain, discomfort, or disorientation from illness can cause a cat to act out defensively (Source: https://undercoverpethouses.com/blog/7-common-feral-cat-behavior-problems-and-how-to-solve-them/).

Finally, a sick stray may go into hiding and isolate themselves from humans or other animals. Whereas healthy cats are generally curious and interactive, a sick cat will tend to find a quiet, sheltered spot to lay low when not feeling well (Source: https://www.thesprucepets.com/cat-behavior-changes-554050).

Diagnostic Tests

There are several diagnostic tests a vet may recommend to check a stray cat’s overall health and screen for diseases:

Complete blood count (CBC) – This common lab test analyzes the numbers of red blood cells, white blood cells, and platelets. It can reveal anemia, infection, inflammation, and blood clotting issues. CBC provides an overview of the cat’s general health.

Fecal exam – Checking a stool sample under a microscope allows vets to look for intestinal parasites like roundworms, hookworms, and protozoa which can cause diarrhea, vomiting, and weight loss. De-worming medication may be prescribed based on fecal exam results.

FeLV/FIV tests – Feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) are highly contagious and can be fatal. All stray cats should be tested for these viruses. Positive results mean steps must be taken to manage disease and prevent transmission.

Skin scraping – By collecting and examining skin cells under a microscope, vets can diagnose parasitic, fungal and bacterial skin infections like ringworm, which causes patchy hair loss and crusty skin lesions. Skin issues are common in stray cats.


[1] https://www.pethealthnetwork.com/cat-health/new-cat-checklists/five-tests-every-new-pet-should-have

[2] https://1stpetvet.com/veterinarian-checklist-for-stray-cats/

Common Diseases

Some of the most common diseases seen in stray and feral cats include:

Upper Respiratory Infections – Cats can catch upper respiratory infections from contact with infected cats or environments. Symptoms include sneezing, runny nose and eyes, fever, and lethargy. Treatment involves antibiotics and supportive care. Some viruses like herpesvirus and calicivirus can cause chronic upper respiratory infections in cats. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/upper-respiratory-infection

Skin Infections – Stray cats are prone to getting cuts, wounds, flea infestations, ringworm fungus, and other skin conditions that can become infected. Treatment involves cleaning and medicating wounds, treating parasites, and using oral/topical antibiotics or antifungals as needed. https://www.alleycat.org/resources/feral-cats-and-the-public-a-healthy-relationship/

Parasites – Intestinal parasites like roundworms, hookworms, and tapeworms are common in strays. They cause diarrhea, vomiting, and malnutrition if left untreated. Regular deworming and flea control helps prevent parasitic infections. https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/zoonotic-disease-what-can-i-catch-my-cat

Feline Leukemia – This contagious viral disease suppresses the cat’s immune system leading to secondary infections. Symptoms include lethargy, poor appetite, fever, and swollen lymph nodes. There is no cure but supportive care can help infected cats. Vaccination prevents infection.

Panleukopenia – Also known as feline distemper, this virus attacks developing cells and suppresses the bone marrow. It causes severe vomiting and diarrhea in kittens and can be fatal. Vaccination provides protection against panleukopenia.

Treating a Sick Stray

Treating a sick stray cat starts with taking it to a veterinarian. However, stray cats can be difficult to trap. Use humane traps baited with smelly food to capture a stray cat. Approach quietly and be patient. Once trapped, immediately transport the cat to a vet clinic or emergency animal hospital in a covered carrier. Inform staff that this is a stray cat.

Veterinarians can diagnose, treat, and prescribe medications for sick stray cats. Treatment will depend on the cat’s symptoms and diagnosis. Common illnesses like upper respiratory infections, fleas, worms, and ear mites can often be treated with medications. More serious conditions like feline leukemia, FIV, trauma, or illness may require intensive treatment and hospitalization (Source). Work with your vet to determine the best course of action based on the cat’s prognosis and your ability to provide aftercare.

Some clinics offer free or discounted care for stray cats as a community service. You may need to call around to find one. Some rescues may also assist with vet bills for strays. If these options are not available, consider crowdfunding, payment plans, or Care Credit to cover costs. The priority is getting the cat medical attention as soon as possible.


The best way to prevent the spread of diseases in stray cat populations is through spay/neuter and vaccination programs. When cats are spayed or neutered, it helps control the population so diseases don’t spread as quickly. Vaccinating community cats against common diseases like rabies and feline leukemia is also crucial. According to Minimizing zoonotic disease risk when caring for community cats, “the vaccination component of TNR programs ensures that the cats in managed colonies cannot catch or transmit rabies.”

Treating community cats with antiparasitics helps prevent the spread of external and internal parasites like fleas, ticks, and worms. Limiting flea infestations is important, as fleas can transmit diseases between cats. According to Health Issues Common in Feral Cats: Prevention and Treatment, parasites like ticks and worms can “irritate and weaken the cat’s immune system, making them more susceptible to disease.” Using antiparasitic medications can help minimize this risk.

Adopting a Stray

If you find a stray cat that you want to adopt, it is important to take proper precautions to protect your existing pets and family members. The initial step should be to quarantine the stray cat for at least 2 weeks (SPCANOVA.org). Keep it isolated in a separate room with food, water, litter box, toys, and bed. Do not allow contact with your other pets during this time.

During the quarantine period, take the stray cat to a veterinarian for a full exam, vaccinations, deworming, and testing for diseases like feline leukemia and FIV. Some shelters and rescue organizations may offer free or discounted vet care for strays. Get any medical issues treated before introducing the cat to your home.

Even after the initial quarantine, continue to monitor the stray cat closely and keep it separated from household pets when unsupervised. It can take several weeks for some illnesses to manifest, so an extended adjustment period is wise. With patience and proper medical care, adopting a stray cat can be very rewarding.

Community Cat Programs

Community cat programs focus on humanely managing unowned outdoor cat populations through trap-neuter-return (TNR). According to Managing community cats – HumanePro, TNR involves trapping community cats, having them spayed/neutered and ear-tipped by a vet, and then returning them to their outdoor home where their colony is located. This stops reproduction and stabilizes the population over time.

Many animal shelters and rescue organizations now operate TNR programs for community cats. For example, Broward County Animal Care’s Community Cat Program offers free spay/neuter, rabies vaccination, and ear tipping to colony caretakers. Best Friends Animal Society also provides resources to implement community cat programs that are proven to be effective alternatives to trap and remove policies.

TNR improves cats’ lives by vaccinating them and stopping the cycle of reproduction. Well-managed colonies can thrive in their outdoor homes. Community cat programs are a humane approach focused on both cat welfare and reducing nuisances or public health concerns.


In conclusion, identifying diseases in stray cats is crucial to protect both cat and human health. Strays often lack regular veterinary care and can develop contagious diseases that spread among the stray population and even to owned pets. By recognizing common symptoms and utilizing diagnostic tests, concerned citizens can help get treatment for sick strays. With interventions like TNR, vaccines, parasite control and adoption programs, communities can humanely reduce stray overpopulation while protecting cats from illness. Caring for stray cats takes a collaborative effort, but it leads to healthier street cats and public health benefits for the whole community.

Educating the public on recognizing and reporting sick strays enables quicker veterinary diagnosis and treatment. And adopting socialized stray kittens and friendly adults is the best way to provide them with the regular care they need. With compassion and teamwork, we can make a difference for stray cat health and welfare.

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